DISPOSITIF DE LEVAGE D'EMBARCATION SECURISE AVEC SYSTEME DE MISE A NIVEAU CONVERTIBLE

FAILSAFE WATERCRAFT LIFT WITH CONVERTIBLE LEVELING SYSTEM

Abrégé français

L'invention concerne un dispositif de levage et d'abaissement d'embarcation dans l'eau, comportant un ponton flottant, un berceau de levage et au moins un bras pivotant. Le berceau de levage comporte au moins un réservoir d'air et un plan de support configuré pour recevoir et supporter l'embarcation. Le réservoir d'air possède une chambre interne configurée de manière à recevoir et à libérer l'air sous pression. La chambre interne présente suffisamment de volume interne pour que lorsqu'elle reçoit suffisamment d'air sous pression le réservoir d'air ait une flottabilité suffisante pour soulever le berceau de levage dans une position relevée avec l'embarcation hors de l'eau lorsqu'elle est positionnée sur le plan de support et pour que lorsque suffisamment d'air sous pression est libéré de la chambre interne, le réservoir d'air perde suffisamment de flottabilité pour rabaisser le berceau de levage jusque dans une position abaissée suffisamment submergée pour recevoir et déployer l'embarcation. Le bras pivotant est connecté à pivotement au ponton et est connecté à pivotement au berceau de levage pour guider le mouvement du berceau de levage entre la position abaissée et la position relevée.

Abrégé anglais

A watercraft lift for raising and lowering a watercraft in water, including a buoyant pontoon, a lifting cradle and at least one pivot arm. The lifting cradle includes at least one air tank and a support bunk configured to receive and support the watercraft. The air tank has an internal chamber configured to receive and release pressurized air. The internal chamber has sufficient internal volume that when sufficient pressurized air is received therein the air tank has sufficient buoyancy to lift the lifting cradle to a raised position with the watercraft out of the water when positioned on the support bunk and that when sufficient pressurized air is released from the internal chamber the air tank loses sufficient buoyancy to sink the lifting cradle to a lowered position sufficiently submerged to receive and deploy the watercraft. The pivot arm is pivotally connected to the pontoon and pivotally connected to the lifting cradle to guide movement of the lifting cradle between the lowered position and the raised position.

Revendications

The invention claimed is:
1. A watercraft lift for raising and lowering a watercraft in water,
comprising:
a buoyant pontoon;
a lifting cradle including at least one air tank with a support bunk
configured to receive and support the watercraft, the air tank having an
internal
chamber configured to receive and release pressurized air, the internal
chamber
having sufficient internal volume that when sufficient pressurized air is
received
therein the air tank has sufficient buoyancy to lift the lifting cradle to a
raised position
with the watercraft out of the water when positioned on the support bunk and
that
when sufficient pressurized air is released from the internal chamber the air
tank
loses sufficient buoyancy to sink the lifting cradle to a lowered position
sufficiently
submerged to receive and deploy the watercraft; and
at least one pivot arm pivotally connected to the pontoon and pivotally
connected to the lifting cradle to guide movement of the lifting cradle
between the
lowered position and the raised position.
2. The watercraft lift of claim 1 wherein the pontoon includes a
buoyant port pontoon portion and a buoyant starboard pontoon portion, the port
and
starboard pontoon portions being spaced apart sufficient to receive the
watercraft
therebetween.
3. The watercraft lift of claim 2 further including ballast positioned
at the port pontoon portion and ballast positioned at the starboard pontoon
portion in
amounts sufficient to prevent the watercraft lift from rolling when the
watercraft is
positioned on the support bunk with the watercraft lift in the raised position
when all
pressurized air is released from the internal chamber the air tank.
4. The watercraft lift of claim 3 wherein the ballast is removably
attached to the port pontoon portion and the ballast is removably attached to
the
starboard pontoon portion.
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5. The watercraft lift of claim 3 wherein the port and starboard
pontoon portions are made of a first material and the ballast is made of a
second
material, the first material being different than the second material.
6. The watercraft lift of claim 1 wherein the pontoon includes a
buoyant port pontoon portion having an end portion and a buoyant starboard
pontoon portion having an end portion, the port and starboard pontoon portions
being spaced apart sufficient to receive the watercraft therebetween, and
further
includes a buoyant connection pontoon portion having the end portions of the
port
and starboard pontoon portions attached thereto, the combined buoyancy of the
port
pontoon portion, the starboard pontoon portion and the connection pontoon
portion
being sufficient the support bunk in sufficient contact with the watercraft to
prevent
the watercraft from floating off of the support bunk when the watercraft is
positioned
on the support bunk with the watercraft lift in the raised position when all
pressurized
air is released from the internal chamber the air tank.
7. The watercraft lift of claim 1 wherein the pontoon includes a
buoyant port pontoon portion having an end portion and a buoyant starboard
pontoon portion having an end portion, the port and starboard pontoon portions
being spaced apart sufficient to receive the watercraft therebetween, and
further
includes a buoyant connection pontoon portion having the end portions of the
port
and starboard pontoon portions attached thereto, the port pontoon portion, the
starboard pontoon portion and the connection pontoon portion having upper
surfaces
arranged to provide a floating dock surface for access to the watercraft from
three
sides thereof when positioned on the support bunk.
8. The watercraft lift of claim 1 wherein the pontoon includes a
buoyant port pontoon portion having an end portion and a buoyant starboard
pontoon portion having an end portion, the port and starboard pontoon portions
being spaced apart sufficient to receive the watercraft therebetween, and
further
includes buoyant port and starboard connection pontoon portions, the end
portion of
the port pontoon portion being attached to the port connection pontoon portion
and
the end portion of the starboard pontoon portion being attached to the
starboard
connection pontoon portion, and the port connection pontoon portion and the
starboard connection pontoon portion being removably attached together.
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9. The watercraft lift of claim 1 further including a lock operable to
lock the pivot arm relative to the pontoon when the lifting cradle is in the
raised
position to prevent downward movement of the pivot arm and thereby movement of
the lifting cradle to the lowered position.
10. The watercraft lift of claim 9 wherein the lock includes a
selectively rotatable upright member having an engagement member attached
thereto, the rotatable member being rotatable between a locked position and an
unlocked position, in the locked position the engagement member being
positioned
in locking engagement with the pivot arm to prevent downward movement of the
pivot arm and thereby movement of the lifting cradle to the lowered position,
and in
the unlocked position the engagement member being positioned out of locking
engagement with the pivot arm to allow downward movement of the pivot arm and
thereby movement of the lifting cradle to the lowered position.
11. The watercraft lift of claim 10 wherein the lock includes a
security member which when engaged prevents rotation of the rotatable member
out
of the locked position.
12. The watercraft lift of claim 1 wherein the pivot arm has an upper
end portion pivotally connected to the pontoon and a lower end portion
pivotally
connected to the air tank of the lifting cradle using a laterally extending
member, the
lower end portion of the pivot arm being connected to an end portion of the
member
to provide a pivotal connection between the lower end portion of the pivot arm
and
the air tank.
13. The watercraft lift of claim 1 wherein the air tank has a
longitudinally extending integrally molded structural rib projecting upward,
the
member extending laterally through the structural rib.
14. The watercraft lift of claim 1 wherein the at least one pivot arm
includes first and second spaced apart port pivot arms, each having an upper
end
portion pivotally connected to the pontoon and a lower end portion pivotally
connected to the lifting cradle, and wherein the air tank has a longitudinally
extending integrally molded structural rib projecting upward and the lower end
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portions of the first and second pivot arms are pivotally connected to the
structural
rib.
15. The watercraft lift of claim 14 wherein the support bunk is
attached to the air tank in a manner to provide longitudinal rigidity to the
air tank.
16. The watercraft lift of claim 1 wherein the air tank has a laterally
projecting portion extending outward to under the pontoon to engage the
pontoon
upon the lifting cradle reaching the raised position.
17. A watercraft lift for raising and lowering a watercraft in water,
comprising:
a buoyant pontoon having a buoyant port pontoon portion with an end
portion, a buoyant starboard pontoon portion with an end portion, and a
buoyant
connection pontoon portion with the end portions of the port and starboard
pontoon
portions attached thereto, the port and starboard pontoon portions being
spaced
apart sufficient to receive the watercraft therebetween;
a lifting cradle including an air tank assembly with a support bunk
configured to receive and support the watercraft, the air tank assembly having
at
least one internal chamber configured to receive and release pressurized air,
the
internal chamber having sufficient internal volume that when sufficient
pressurized
air is received therein the air tank assembly has sufficient buoyancy to lift
the lifting
cradle to a raised position with the watercraft out of the water when
positioned on the
support bunk and that when sufficient pressurized air is released from the
internal
chamber the air tank assembly loses sufficient buoyancy to sink the lifting
cradle to a
lowered position sufficiently submerged to receive and deploy the watercraft;
and
at least one port pivot arm pivotally connected to the port pontoon
portion and pivotally connected to the lifting cradle, and at least one
starboard pivot
arm pivotally connected to the starboard pontoon portion and pivotally
connected to
the lifting cradle, the port and starboard pivot arms configured to guide
movement of
the lifting cradle between the lowered position and the raised position.
18. The watercraft lift of claim 17 wherein the port and starboard
pivot arms are pivotally connected to the lifting cradle using a member
extending
between a port side of the lifting cradle and a starboard side of the lifting
cradle, the
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port pivot arm being connected to a port end of the member and the starboard
pivot
arm being connected to a starboard end of the member.
19. The watercraft lift of claim 18 wherein the member is a torsion
bar.
20. The watercraft lift of claim 17 wherein the pontoon includes a
buoyant port pontoon portion having an end portion and a buoyant starboard
pontoon portion having an end portion, the port and starboard pontoon portions
being spaced apart sufficient to receive the watercraft therebetween, and
further
includes a buoyant connection pontoon portion having the end portions of the
port
and starboard pontoon portions attached thereto, the combined buoyancy of the
port
pontoon portion, the starboard pontoon portion and the connection pontoon
portion
being sufficient the support bunk in sufficient contact with the watercraft to
prevent
the watercraft from floating off of the support bunk when the watercraft is
positioned
on the support bunk with the watercraft lift in the raised position when all
pressurized
air is released from the internal chamber the air tank assembly.
21. The watercraft lift of claim 17 further including a first lock
operable to lock the port pivot arm relative to the port pontoon portion when
the lifting
cradle is in the raised position to prevent downward movement of the port
pivot arm
and thereby movement of the lifting cradle to the lowered position, and a
second lock
operable to lock the starboard pivot arm relative to the starboard pontoon
portion
when the lifting cradle is in the raised position to prevent downward movement
of the
starboard pivot arm and thereby movement of the lifting cradle to the lowered
position.
22. The watercraft lift of claim 21 wherein the first lock includes a
selectively rotatable first rotatable upright member having a first engagement
member attached thereto, the first rotatable member being roatatable supported
by
the port pontoon portion and rotatable between a locked position and an
unlocked
position, in the locked position the first engagement member being positioned
in
locking engagement with the port pivot arm to prevent downward movement of the
port pivot arm and thereby movement of the lifting cradle to the lowered
position, and
in the unlocked position the engagement member being positioned out of locking

engagement with the port pivot arm to allow downward movement of the port
pivot
arm and thereby movement of the lifting cradle to the lowered position, and a
selectively rotatable second rotatable upright member having a second
engagement
member attached thereto, the second rotatable member being roatatable
supported
by the starboard pontoon portion and rotatable between a locked position and
an
unlocked position, in the locked position the second engagement member being
positioned in locking engagement with the starboard pivot arm to prevent
downward
movement of the starboard pivot arm and thereby movement of the lifting cradle
to
the lowered position, and in the unlocked position the engagement member being
positioned out of locking engagement with the starboard pivot arm to allow
downward movement of the starboard pivot arm and thereby movement of the
lifting
cradle to the lowered position.
23. The watercraft lift of claim 22 wherein the first lock includes a
first security member which when engaged prevents rotation of the first
rotatable
member out of the locked position, and the second lock includes a second
security
member when engaged prevents rotation of the second rotatable member out of
the
locked position.
24. The watercraft lift of claim 17 wherein the port and starboard
pivot arms each have an upper end portion and a lower end portion, the upper
end
portion of the port pivot arm being pivotally connected to the port pontoon
portion
and the lower end portion of the port pivot arm being pivotally connected to
the air
tank assembly of the lifting cradle, and the upper end portion of the
starboard pivot
arm being pivotally connected to the starboard pontoon portion and the lower
end
portion of the starboard pivot arm being pivotally connected to the air tank
assembly
of the lifting cradle.
25. The watercraft lift of claim 24 further including a member
extending between a port side of the air tank assembly and a starboard side of
the
air tank assembly, the lower end portion of the port pivot arm being connected
to a
port end of the member and the lower end portion of the starboard pivot arm
being
connected to a starboard end of the member.
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26. The watercraft lift of claim 17 wherein the air tank assembly has
a longitudinally extending integrally molded structural rib projecting upward,
the
member extending laterally through the structural rib.
27. The watercraft lift of claim 17 wherein the at least one port pivot
arm includes first and second spaced apart port pivot arms, each having an
upper
end portion pivotally connected to the port pontoon portion and a lower end
portion
pivotally connected to the lifting cradle, and the at least one starboard
pivot arm
includes first and second spaced apart starboard pivot arms, each having an
upper
end portion pivotally connected to the starboard pontoon portion and a lower
end
portion pivotally connected to the lifting cradle, and wherein the air tank
assembly
has a longitudinally extending integrally molded structural rib projecting
upward and
the lower end portions of the first and second port and starboard pivot arms
are
pivotally connected to the structural rib.
28. The watercraft lift of claim 27 wherein the support bunk is
attached to the air tank assembly in a manner to provide longitudinal rigidity
to the air
tank assembly.
29. The watercraft lift of claim 17 wherein the air tank has a laterally
projecting portion extending outward to under the pontoon to engage the
pontoon
upon the lifting cradle reaching the raised position.
30. A watercraft lift for raising and lowering a watercraft in water,
comprising:
a buoyant pontoon having a buoyant port pontoon portion with an end
portion, a buoyant starboard pontoon portion with an end portion, and a
buoyant
connection pontoon portion with the end portions of the port and starboard
pontoon
portions attached thereto, the port and starboard pontoon portions being
spaced
apart sufficient to receive the watercraft therebetween;
a lifting cradle with watercraft supports and including a port internal
chamber configured to receive and release pressurized air, and a starboard
internal
chamber configured to receive and release pressurized air, the watercraft
supports
being configured to receive and support the watercraft, the combined port and
starboard internal chambers having sufficient internal volume that when
sufficient
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pressurized air is received therein the lifting cradle has sufficient buoyancy
to lift the
lifting cradle to a raised position with the watercraft out of the water when
positioned
on the watercraft supports and that when sufficient pressurized air is
released from
the port and starboard internal chambers the lifting cradle loses sufficient
buoyancy
to sink the lifting cradle to a lowered position sufficiently submerged to
receive and
deploy the watercraft; and
at least one port pivot arm having an upper end portion pivotally
connected to the port pontoon portion and a lower end portion pivotally
connected to
the lifting cradle, and at least one starboard pivot arm having an upper end
portion
pivotally connected to the starboard pontoon portion and a lower end portion
pivotally connected to the lifting cradle, the port and starboard pivot arms
configured
to guide movement of the lifting cradle between the lowered position and the
raised
position.
31. The watercraft lift of claim 30 wherein a lifting cradle includes at
least one port air tank defining the port internal chamber and at least one
starboard
air tank defining the starboard internal chamber.
32. The watercraft lift of claim 31 further including a hydrodynamic
brake extending between the port and starboard air tanks to create additional
resistance against movement of the lifting cradle.
33. The watercraft lift of claim 31 wherein the lower end portion of
the port pivot arm is pivotally connected to the port air tank of the lifting
cradle, and
the lower end portion of the starboard pivot arm is pivotally connected to the
starboard air tank of the lifting cradle.
34. The watercraft lift of claim 33 wherein the lower end portions of
the port and starboard pivot arms are pivotally connected to the port and
starboard
air tanks of the lifting cradle using a member extending between a port side
of the
port air tank and a starboard side of the starboard air tank, the lower end
portion of
the port pivot arm being connected to a port end of the member and the lower
end
portion of the starboard pivot arm being connected to a starboard end of the
member.
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35. The watercraft lift of claim 34 wherein the member is a torsion
bar extending through an aperture in the port and starboard air tanks.
36. The watercraft lift of claim 31 wherein the port air tank has a
laterally projecting portion extending outward to under the port pontoon
portion to
engage the port pontoon portion upon the lifting cradle reaching the raised
position,
and the starboard air tank has a laterally projecting portion extending
outward to
under the starboard pontoon portion to engage the starboard pontoon portion
upon
the lifting cradle reaching the raised position.
37. The watercraft lift of claim 30 further including a port relief port
communicating with the port internal chamber and a starboard relief port
communicating with the starboard internal chamber, the port and starboard
relief
ports being arranged to permit the release of pressurized air in one of the
port
internal chamber and the starboard internal chamber based on which is least
submerged in the water.
38 The watercraft lift of claim 37 wherein a lifting cradle includes at
least one port air tank defining the port internal chamber and at least one
starboard
air tank defining the starboard internal chamber, and the port relief port is
positioned
at a port side of the port air tank and the starboard relief port is
positioned at a
starboard side of the starboard air tank.
39. The watercraft lift of claim 30 further including a hydrodynamic
brake extending between the port and starboard air tanks to create additional
resistance against movement of the lifting cradle.
40. The watercraft lift of claim 30 for conversion for use with a slip
having port and starboard side members, wherein the upper end portion of the
port
pivot arm is removably connected to the port pontoon portion and pivotally
attachable to the port side member of the slip, and the upper end portion of
the
starboard pivot arm is removably connected to the starboard pontoon portion
and
pivotally attachable to the starboard side member of the slip.
41. The watercraft lift of claim 30 wherein the port and starboard
pontoon portions are each a rotomolded plastic part.
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42. A watercraft lift for raising and lowering a watercraft in water,
comprising:
a buoyant pontoon having a buoyant port pontoon portion with an end
portion, a buoyant starboard pontoon portion with an end portion, and a
buoyant
connection pontoon portion with the end portions of the port and starboard
pontoon
portions attached thereto, the port and starboard pontoon portions being
spaced
apart sufficient to receive the watercraft therebetween;
a lifting cradle including a port air tank with a port watercraft support
and having an internal chamber configured to receive and release pressurized
air,
and a starboard air tank with a starboard watercraft support and having an
internal
chamber configured to receive and release pressurized air, the port and
starboard
watercraft supports being configured to receive and support the watercraft,
the
combined internal chambers of the port and starboard air tanks having
sufficient
internal volume that when sufficient pressurized air is received therein the
port and
starboard air tanks have sufficient buoyancy to lift the lifting cradle to a
raised
position with the watercraft out of the water when positioned on the port and
starboard watercraft supports and that when sufficient pressurized air is
released
from the internal chambers of the port and starboard air tanks the air tanks
loses
sufficient buoyancy to sink the lifting cradle to a lowered position
sufficiently
submerged to receive and deploy the watercraft; and
first and second spaced apart port pivot arms, each having an upper
end portion pivotally connected to the port pontoon portion and a lower end
portion
pivotally connected to the lifting cradle, and first and second spaced apart
starboard
pivot arms, each having an upper end portion pivotally connected to the
starboard
pontoon portion and a lower end portion pivotally connected to the lifting
cradle, the
port and starboard pivot arms configured to guide movement of the lifting
cradle
between the lowered position and the raised position, the first and second
port pivot
arms, the port pontoon portion and the lifting cradle being in a 4-bar linkage
arrangement and the first and second starboard pivot arms, the starboard
pontoon
portion and the lifting cradle being in a 4-bar linkage arrangement.
43. The watercraft lift of claim 42 wherein the lower end portions of
the first and second port pivot arms are pivotally connected to the port air
tank of the

lifting cradle, and the lower end portions of the first and second of the
starboard pivot
arms are pivotally connected to the starboard air tank of the lifting cradle.
44. The watercraft lift of claim 43 wherein the lower end portions of
the first port pivot arm and the first starboard pivot arm are pivotally
connected to the
port and starboard air tanks of the lifting cradle using a first member
extending
between a port side of the port air tank and a starboard side of the starboard
air tank,
the lower end portion of the first port pivot arm being connected to a port
end of the
first member and the lower end portion of the first starboard pivot arm being
connected to a starboard end of the first member, and wherein the lower end
portions of the second port pivot arm and the second starboard pivot arm are
pivotally connected to the port and starboard air tanks of the lifting cradle
using a
second member extending between a port side of the port air tank and a
starboard
side of the starboard air tank and spaced apart from the first member, the
lower end
portion of the second port pivot arm being connected to a port end of the
second
member and the lower end portion of the second starboard pivot arm being
connected to a starboard end of the second member.
45. The watercraft lift of claim 44 wherein the first and second
member are a torsion bars, each extending through an aperture in the port and
starboard air tanks.
46. The watercraft lift of claim 44 wherein the port and starboard air
tanks each have a longitudinally extending integrally molded structural rib
projecting
upward, the first member extending through the structural rib of the port and
starboard air tanks, and the second member extending through the structural
rib of
the port and starboard air tanks.
47. The watercraft lift of claim 43 wherein the port and starboard air
tanks each have a longitudinally extending integrally molded structural rib
projecting
upward, and the lower end portions of the first and second port pivot arms are
pivotally connected to the structural rib of the port air tank and the lower
end portions
of the first and second starboard pivot arms are pivotally connected to the
structural
rib of the starboard air tank.
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48. The watercraft lift of claim 47 wherein the port watercraft support
is a bunk attached to the port air tank in a manner to provide longitudinal
rigidity to
the port air tank, and the starboard watercraft support is a bunk attached to
the
starboard air tank in a manner to provide longitudinal rigidity to the
starboard air
tank.
49. The watercraft lift of claim 42 further including a port relief port
communicating with the interior chamber of the port air tank and a starboard
relief
port communicating with the interior chamber of the starboard air tank, the
port and
starboard relief ports being arranged to permit the release of pressurized air
in the
interior chamber of the one of the port and starboard air tanks that is least
submerged in the water.
50. The watercraft lift of claim 49 wherein the port relief port is
positioned at the port side of the port air tank and the starboard relief port
is
positioned at the starboard side of the starboard air tank.
51. The watercraft lift of claim 42 further including a first lock
operable to lock one of the first and second port pivot arms relative to the
port
pontoon portion when the lifting cradle is in the raised position to prevent
downward
movement of the one port pivot arm and thereby movement of the lifting cradle
to the
lowered position, and a second lock operable to lock one of the first and
second
starboard pivot arms relative to the starboard pontoon portion when the
lifting cradle
is in the raised position to prevent downward movement of the one starboard
pivot
arm and thereby movement of the lifting cradle to the lowered position.
52. The watercraft lift of claim 51 wherein the first lock includes a
selectively rotatable first rotatable upright member having a first engagement
member attached thereto, the first rotatable member being roatatable supported
by
the port pontoon portion and rotatable between a locked position and an
unlocked
position, in the locked position the first engagement member being positioned
in
locking engagement with the one port pivot arm to prevent downward movement of
the one port pivot arm and thereby movement of the lifting cradle to the
lowered
position, and in the unlocked position the engagement member being positioned
out
of locking engagement with the one port pivot arm to allow downward movement
of
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the one port pivot arm and thereby movement of the lifting cradle to the
lowered
position, and a selectively rotatable second rotatable upright member having a
second engagement member attached thereto, the second rotatable member being
roatatable supported by the starboard pontoon portion and rotatable between a
locked position and an unlocked position, in the locked position the second
engagement member being positioned in locking engagement with the one
starboard
pivot arm to prevent downward movement of the one starboard pivot arm and
thereby movement of the lifting cradle to the lowered position, and in the
unlocked
position the engagement member being positioned out of locking engagement with
the one starboard pivot arm to allow downward movement of the one starboard
pivot
arm and thereby movement of the lifting cradle to the lowered position.
53. The watercraft lift of claim 52 wherein the first lock includes a
first security member which when engaged prevents rotation of the first
rotatable
member out of the locked position, and the second lock includes a second
security
member when engaged prevents rotation of the second rotatable member out of
the
locked position.
54. A watercraft lift for raising and lowering a watercraft in water,
attachable to a slip having a port side and a starboard side, the watercraft
lift
comprising:
a lifting cradle including a port air tank with a port support bunk and
having an internal chamber configured to receive and release pressurized air,
and a
starboard air tank with a starboard support bunk and having an internal
chamber
configured to receive and release pressurized air, the port and starboard
support
bunks being configured to receive and support the watercraft, the combined
internal
chambers of the port and starboard air tanks having sufficient internal volume
that
when sufficient pressurized air is received therein the port and starboard air
tanks
have sufficient buoyancy to lift the lifting cradle to a raised position with
the
watercraft out of the water when positioned on the port and starboard support
bunks
and that when sufficient pressurized air is released from the internal
chambers of the
port and starboard air tanks the air tanks loses sufficient buoyancy to sink
the lifting
cradle to a lowered position sufficiently submerged to receive and deploy the
watercraft;
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first and second spaced apart port pivot arms, each having an upper
end portion pivotally connectable to the port side of the slip and a lower end
portion
pivotally connected to the lifting cradle, and first and second spaced apart
starboard
pivot arms, each having an upper end portion pivotally connectable to the
starboard
side of the slip and a lower end portion pivotally connected to the lifting
cradle, the
port and starboard pivot arms configured to guide movement of the lifting
cradle
between the lowered position and the raised position, the first and second
port pivot
arms, the port side of the slip and the lifting cradle forming a 4-bar linkage
arrangement and the first and second starboard pivot arms, the starboard side
of the
slip and the lifting cradle forming a 4-bar linkage arrangement; and
a first lock operable to lock one of the first and second port pivot arms
relative to the port side of the slip when the lifting cradle is in the raised
position to
prevent downward movement of the one port pivot arm and thereby movement of
the
lifting cradle to the lowered position, and a second lock operable to lock one
of the
first and second starboard pivot arms relative to the starboard side of the
slip when
the lifting cradle is in the raised position to prevent downward movement of
the one
starboard pivot arm and thereby movement of the lifting cradle to the lowered
position.
55. The watercraft lift of claim 54 wherein the first lock includes a
selectively rotatable first rotatable upright member having a first engagement
member attached thereto, the first rotatable member being roatatable supported
by
the port side of the slip and rotatable between a locked position and an
unlocked
position, in the locked position the first engagement member being positioned
in
locking engagement with the one port pivot arm to prevent downward movement of
the one port pivot arm and thereby movement of the lifting cradle to the
lowered
position, and in the unlocked position the engagement member being positioned
out
of locking engagement with the one port pivot arm to allow downward movement
of
the one port pivot arm and thereby movement of the lifting cradle to the
lowered
position, and a selectively rotatable second rotatable upright member having a
second engagement member attached thereto, the second rotatable member being
rotatable supported by the starboard side of the slip and rotatable between a
locked
position and an unlocked position, in the locked position the second
engagement
member being positioned in locking engagement with the one starboard pivot arm
to
49

prevent downward movement of the one starboard pivot arm and thereby movement
of the lifting cradle to the lowered position, and in the unlocked position
the
engagement member being positioned out of locking engagement with the one
starboard pivot arm to allow downward movement of the one starboard pivot arm
and thereby movement of the lifting cradle to the lowered position.
56. The watercraft lift of claim 55 wherein the first lock includes a
first security member which when engaged prevents rotation of the first
rotatable
member out of the locked position, and the second lock includes a second
security
member when engaged prevents rotation of the second rotatable member out of
the
locked position.
57. A watercraft lift for raising and lowering a watercraft in water,
attachable to a slip having a port side and a starboard side, the watercraft
lift
comprising:
a lifting cradle including a port air tank with a port support bunk and
having an internal chamber configured to receive and release pressurized air,
and a
starboard air tank with a starboard support bunk and having an internal
chamber
configured to receive and release pressurized air, the port and starboard
support
bunks being configured to receive and support the watercraft, the combined
internal
chambers of the port and starboard air tanks having sufficient internal volume
that
when sufficient pressurized air is received therein the port and starboard air
tanks
have sufficient buoyancy to lift the lifting cradle to a raised position with
the
watercraft out of the water when positioned on the port and starboard support
bunks
and that when sufficient pressurized air is released from the internal
chambers of the
port and starboard air tanks the air tanks loses sufficient buoyancy to sink
the lifting
cradle to a lowered position sufficiently submerged to receive and deploy the
watercraft;
first and second spaced apart port pivot arms, each having an upper
end portion pivotally connectable to the port side of the slip and a lower end
portion
pivotally connected to the lifting cradle, and first and second spaced apart
starboard
pivot arms, each having an upper end portion pivotally connectable to the
starboard
side of the slip and a lower end portion pivotally connected to the lifting
cradle, the
port and starboard pivot arms configured to guide movement of the lifting
cradle

between the lowered position and the raised position, the first and second
port pivot
arms, the port side of the slip and the lifting cradle forming a 4-bar linkage
arrangement and the first and second starboard pivot arms, the starboard side
of the
slip and the lifting cradle forming a 4-bar linkage arrangement; and
a first member attached to port and starboard air tanks and extending
between a port side of the port air tank and a starboard side of the starboard
air tank,
the lower end portions of the first port pivot arm and the first starboard
pivot arm
being pivotally connected to the port and starboard air tanks of the lifting
cradle using
the first member, the lower end portion of the first port pivot arm being
connected to
a port end of the first member and the lower end portion of the first
starboard pivot
arm being connected to a starboard end of the first member; and
a second member attached to port and starboard air tanks and
extending between a port side of the port air tank and a starboard side of the
starboard air tank and spaced apart from the first member, the lower end
portions of
the second port pivot arm and the second starboard pivot arm being pivotally
connected to the port and starboard air tanks of the lifting cradle using the
second
member, the lower end portion of the second port pivot arm being connected to
a
port end of the second member and the lower end portion of the second
starboard
pivot arm being connected to a starboard end of the second member.
58. The watercraft lift of claim 57 wherein the first and second
member are a torsion bars, each extending through an aperture in the port and
starboard air tanks.
59. The watercraft lift of claim 57 wherein the port and starboard air
tanks each have a longitudinally extending integrally molded structural rib
projecting
upward, the first member extending through the structural rib of the port and
starboard air tanks, and the second member extending through the structural
rib of
the port and starboard air tanks.
60. The watercraft lift of claim 57 wherein the port support bunk is
attached to the port air tank in a manner to provide longitudinal rigidity to
the port air
tank, and the starboard support bunk is attached to the starboard air tank in
a
manner to provide longitudinal rigidity to the starboard air tank.
51

61. A watercraft lift for raising and lowering a watercraft in water,
attachable to a slip having a port side and a starboard side, the watercraft
lift
comprising:
a lifting cradle including a port air tank with a port support bunk and
having an internal chamber configured to receive and release pressurized air,
and a
starboard air tank with a starboard support bunk and having an internal
chamber
configured to receive and release pressurized air, the port and starboard
support
bunks being configured to receive and support the watercraft, the combined
internal
chambers of the port and starboard air tanks having sufficient internal volume
that
when sufficient pressurized air is received therein the port and starboard air
tanks
have sufficient buoyancy to lift the lifting cradle to a raised position with
the
watercraft out of the water when positioned on the port and starboard support
bunks
and that when sufficient pressurized air is released from the internal
chambers of the
port and starboard air tanks the air tanks loses sufficient buoyancy to sink
the lifting
cradle to a lowered position sufficiently submerged to receive and deploy the
watercraft;
first and second spaced apart port pivot arms, each having an upper
end portion pivotally connectable to the port side of the slip and a lower end
portion
pivotally connected to the lifting cradle, and first and second spaced apart
starboard
pivot arms, each having an upper end portion pivotally connectable to the
starboard
side of the slip and a lower end portion pivotally connected to the lifting
cradle, the
port and starboard pivot arms configured to guide movement of the lifting
cradle
between the lowered position and the raised position, the first and second
port pivot
arms, the port side of the slip and the lifting cradle forming a 4-bar linkage
arrangement and the first and second starboard pivot arms, the starboard side
of the
slip and the lifting cradle forming a 4-bar linkage arrangement; and
a hydrodynamic brake extending between the port and starboard air
tanks to create additional resistance against movement of the lifting cradle.
52

Description

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PCT PATENT
FAILSAFE WATERCRAFT LIFT WITH CONVERTIBLE LEVELING SYSTEM
Field of the Invention
The invention generally relates to an apparatus and method for lifting
watercraft out of the water.
Description of the Related Art
The use of watercraft lifting devices is well known. Out-of-water storage
prevents damage resulting from boat contact with docks, other craft or
floating
debris. It reduces the possibility of the boat breaking free from its moorage
and
floating adrift or running aground. Out-of-water storage also lessens boat
damage
associated with long-term exposure to water and water-based pollutants and the
attachment of barnacles or other marine growth to the boat's hull. Once a boat
is
lifted it can be maintained in its position for extended periods of time,
relieving the
user of maintenance concerns. In certain situations where the water
fluctuation is
high, water depth is too deep, or permanent mounting is undesired, floating
watercraft lifting devices are used. A number of floating lift designs are
currently
known that provide this basic function.
US Pat. No. 5,002,000 to Rutter uses air filled pontoons as a lifting device
combined with a complicated array of air inlet and outlet valves to control
lateral
stability while lifting. With this device the rear portion of the pontoons are
lowered
more than the forward portion of the pontoons to allow ingress and egress of
the
boat. This device, however, is limited in that the watercraft will not be
raised or
lowered in a horizontal position which is undesirable to many users.
US Pat. No. 5,860,379 to Moody comprises of an inflatable fabric air
chamber as the lifting device. While this device raises the boat out of the
water, it
has many disadvantages including a complicated rope tying configuration for
stabilizing, non-horizontal lifting by raising the bow of the watercraft
before the
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stern, and incompatibility with all boats by only fitting boats with outboard
and
inboard/outboard motors.
US Pat. No. 6,848,380 to Sainz is a floating watercraft lift that addresses
the fore and aft stability issues and non-horizontal lifting with the
boatlifts
described in Moody and Rutter by using air chambers with an arcuate
longitudinal
top surface and a base side that is flat. While addressing these stability
issues,
the lift suffers from a number of disadvantages including the lack of a means
for
keeping the lift stable if air pressure is lost in one or all pontoon
chambers, the
ability to fit in a narrow boat slip, and the lack of reserve buoyancy to keep
the
device from sinking if all air pressure is lost.
Two known devices, one from Hydrohoist International, Inc. and the other
from Shoremaster, address the fore and aft stability and non-horizontal
lifting
described in Moody and Rutter in another fashion. Both devices are air
displacement watercraft lifts using stabilizing brackets fixed to a dock or
slip to
maintain horizontal lifting of the watercraft. These fixed stabilizing
brackets are
undesirable for marina operations and limit the ease of portability for these
lifts. A
similar method for stabilizing a boat lift is described in US Pat. No.
4,750,444 to
Lemvig, wherein the lift is comprised of a platform with a deck and lifting
skirt and
link arms connecting the platform to a quay. Air is supplied to the lifting
skirt to
raise a watercraft while the link arms attached to the quay stabilize the
platform.
Similar to the Hydrohoist and Shoremaster devices, the device of Lemvig
requires
link arms fixed to a quay to stabilize the lift limiting the portability of
the lift.
Hydrohoist International, Inc. and Airberth address portability issues with
free floating side tie lifts. These lifts use air tanks rigidly attached to
side
floatation to control lifting and stability. While allowing for portability
and side tie
capabilities, these lifts do not raise the watercraft in a horizontal position
and have
similar disadvantages to Rutter and Moody.
In addition to the above stated short comings, the floating watercraft lifts
of
Rutter, Moody, Sainz, Hydrohoist, Shoremaster and Air Berth may inadvertently
lower the watercraft into the water if air pressure is not maintained in one
or all air
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chambers. In this case the watercraft will become susceptible to the damaging
elements described above.
Another difficulty facing floating watercraft lift manufacturers is the
multitude of mounting scenarios. To meet the lift mounting requirements, the
manufacturers offer different lifts for slip, side-tie and forward mounting
applications. By offering three different lifts the manufacturer and dealer
must
increase inventory levels and warehouse storage space.
Accordingly, there is a need in the art for a floating watercraft lift that
addresses all of the following issues of horizontal lifting of the watercraft
with a
desirable stabilizing feature, compatibility with all boat drive
configurations,
stability if air pressure is lost in one or all air chambers, the ability to
fit in narrow
boat slips, portability for ease of installation and removal, damage tolerance
to
keep the watercraft out of the water if one or all of the air chambers lose
air
pressure, and convertibility to most floating watercraft lift mounting
scenarios.
Summary of the Invention
A watercraft lift for raising and lowering a watercraft in water. The
watercraft lift includes a buoyant pontoon, a lifting cradle and at least one
pivot
arm. The lifting cradle includes at least one air tank and a support bunk
configured to receive and support the watercraft. The air tank has an internal
chamber configured to receive and release pressurized air. The internal
chamber
has sufficient internal volume that when sufficient pressurized air is
received
therein the air tank has sufficient buoyancy to lift the lifting cradle to a
raised
position with the watercraft out of the water when positioned on the support
bunk
and that when sufficient pressurized air is released from the internal chamber
the
air tank loses sufficient buoyancy to sink the lifting cradle to a lowered
position
sufficiently submerged to receive and deploy the watercraft. The pivot arm is
pivotally connected to the pontoon and pivotally connected to the lifting
cradle to
guide movement of the lifting cradle between the lowered position and the
raised
position.
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In one embodiment the pontoon includes a buoyant port pontoon portion
and a buoyant starboard pontoon portion. The port and starboard pontoon
portions are spaced apart sufficient to receive the watercraft therebetween.
The watercraft lift may further include ballast removably attached to the
port pontoon portion and ballast removably attached to the starboard pontoon
portion in amounts sufficient to prevent the watercraft lift from rolling when
the
watercraft is positioned on the support bunk with the watercraft lift in the
raised
position when all pressurized air is released from the internal chamber the
air
tank. The port and starboard pontoon portions are made of a first material and
the ballast is made of a second material, the first material being different
than the
second material.
The pontoon includes a buoyant port pontoon portion having an end
portion and a buoyant starboard pontoon portion having an end portion. The
port
and starboard pontoon portions are spaced apart sufficient to receive the
watercraft therebetween. The pontoon further includes a buoyant connection
pontoon portion having the end portions of the port and starboard pontoon
portions attached thereto. The combined buoyancy of the port pontoon portion,
the starboard pontoon portion and the connection pontoon portion is sufficient
hold the watercraft out of the water when the watercraft is positioned on the
support bunk with the watercraft lift in the raised position when all
pressurized air
is released from the internal chamber the air tank.
The port pontoon portion, the starboard pontoon portion and the
connection pontoon portion have upper surfaces arranged to provide a floating
dock surface for access to the watercraft from three sides thereof when
positioned
on the support bunk.
The connection pontoon portion has buoyant port and starboard
connection pontoon portions, with the end portion of the port pontoon portion
attached to the port connection pontoon portion and the end portion of the
starboard pontoon portion attached to the starboard connection pontoon
portion.
The port connection pontoon portion and the starboard connection pontoon
portion are removably attached together.
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The watercraft lift may further include a lock operable to lock the pivot arm
relative to the pontoon when the lifting cradle is in the raised position to
prevent
downward movement of the pivot arm and thereby movement of the lifting cradle
to the lowered position. The lock includes a selectively rotatable upright
member
having an engagement member attached thereto, the rotatable member being
rotatable between a locked position and an unlocked position. In the locked
position the engagement member is positioned in locking engagement with the
pivot arm to prevent downward movement of the pivot arm and thereby movement
of the lifting cradle to the lowered position. In the unlocked position the
engagement member is positioned out of locking engagement with the pivot arm
to allow downward movement of the pivot arm and thereby movement of the
lifting
cradle to the lowered position. The lock may include a security member which
when engaged prevents rotation of the rotatable member out of the locked
position.
Other features and advantages of the invention will become apparent from
the following detailed description, taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
The foregoing aspects and many of the attendant advantages of this
invention will become more readily appreciated as the same becomes better
understood by reference to the following detailed description, when taken in
conjunction with the accompanying drawings, which are schematic, and not to
scale, wherein:
FIGURE 1 is an isometric view of a watercraft lift according to the present
invention in a lowered position.
FIGURE 2 is an isometric view of the watercraft lift of Figure 1 in a position
between a raised position and the lowered position.
FIGURE 3 is an isometric view of the watercraft lift of Figure 1 in the raised
position.
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FIGURE 4 is an enlarged, isometric view of an air tank of the watercraft lift
of Figure 1.
FIGURE 5 is an enlarged, isometric view of a lifting cradle of the watercraft
lift of Figure 1.
FIGURE 6 is an isometric view of ballasted floating pontoons of the
watercraft lift of Figure 1.
FIGURE 7 is a side view of a swing arm of the watercraft lift of Figure 1.
FIGURE 8 is an front view of the swing arm and torsion bar assembly of
the watercraft lift of Figure 1.
FIGURE 9 is a sectional side elevational view of the watercraft lift of Figure
1 showing a 4-bar linkage arrangement of the swing arms.
FIGURE 10 is an enlarged, isometric view of a lock mechanism of the
watercraft lift of Figure 1.
FIGURE 11 is a rear elevational view of the watercraft lift of Figure 1 in the
lowered position with the watercraft in the load/unload position.
FIGURE 12 is a rear elevational view of the watercraft lift of Figure 1 in the
raised position with the watercraft in the stored position.
FIGURE 13 is a top plan view of the watercraft lift of Figure 1 in a 4-point
tie configuration in a slip.
FIGURE 14 is a top plan view of the watercraft lift of Figure 1 in a forward
mounting tie configuration.
FIGURE 15 is a top plan view of the watercraft lift of Figure 1 in a side tie
configuration.
FIGURE 16 is an isometric view of the watercraft lift of Figure 1 with a
canopy mounted to the floating pontoons.
FIGURE 17 is an isometric view of the watercraft lift of Figure 1 with a
hydrodynamic element to control the acceleration and velocity of raising and
lowering the lifting cradle.
FIGURE 18 is an isometric view of multiple watercraft lifts of the type
shown in Figure 1 mounted side by side.
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FIGURE 19 is an isometric view of the watercraft lift of Figure 1 with air
hoses routed through a center of the watercraft lift.
FIGURE 20 is an isometric view of the watercraft lift of Figure 1 with the
floating pontoons removed and swing arms pivotally attached to a slip.
DETAILED DESCRIPTION OF THE INVENTION
This section illustrates aspects of the invention, and points out certain
preferred embodiments of these aspects. This section is not intended to be
exhaustive, but rather to inform and teach the person of skill in the art who
will
come to appreciate more fully other aspects, equivalents, and possibilities
presented by invention, and hence the scope of the invention is set forth in
the
claims, which alone limit its scope.
Several embodiments of the invention are set forth in the following
description: Figures 1 through 20 provide a thorough understanding of such
embodiments. One skilled in the art will understand that the present invention
may be practiced without several of the details described herein. In the
following
description of the embodiments, it is understood that a watercraft includes
any
vehicle that is at least partially waterborne, which includes boats and
similar
vessels, but may also include amphibious vehicles including various amphibious
automobiles or aircraft. Moreover, in the description that follows, it is
understood
that the figures related to the various embodiments are not to be interpreted
as
conveying any specific or relative physical dimension, and that specific or
relative
dimensions related to the various embodiments, if stated, are not be
considered
limiting unless future claims state otherwise.
An isometric view of a watercraft lift 10 in a fully lowered position is shown
in Figure 1. The watercraft lift 10, having a port side A and a starboard side
B,
includes a lifting cradle 50 comprising two air tanks 40 each having a lifting
bunk
51, and a pair of port and starboard floating pontoons 60 with the lifting
cradle
positioned between the laterally spaced apart rearward portions of the
floating
pontoons. Fore and aft pivotal connectors 80 pivotally connect the lifting
cradle
50 to the floating pontoons 60. Each pivotal connector 80 includes a torsion
bar
7

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81 extending through the lifting cradle 50 and two swing arm 70 attached to
the
torsion bar, one on each side of the lifting cradle. One swing arm 70 of the
pivotal
connector 80 is pivotally connected to the port floating pontoon 60, and the
other
swing arm of the pivotal connector is pivotally connected to the starboard
floating
pontoon 60. As best seen in Figure 9 for the port side A, the swing arms 70 of
the
fore and aft pivotal connectors 80 are pivotally attached at points 91 and 92
on
the port floating pontoon 60 and are also pivotally attached to the lifting
cradle 50
at points 43 and 44. The lower ends of the swing arms 70 rotate forward and
upwardly towards the forward floats 61 as air volume is increased within the
air
tanks 40. The lifting bunks 51 provide support to the hull of a watercraft 111
when
in engagement therewith as shown in Figure 12.
Again referring to Figure 1, each floating pontoon 60 has a forward float 61,
three side floats 62, side ballasts 63 and forward ballast 64. As will be
described
below, these floats are connected together to form a dock like structure for
access
to the watercraft 111 using the watercraft lift 10 from three sides.
Figure 2 shows the watercraft lift 10 in a partially raised position from the
lowered position shown in Figure 1 which results from the pumping of air into
the
air tanks 40 of the lifting cradle 50 and the resulting purging of the water
therein.
As the air volume is increased within the air tanks 40, the lifting cradle 50
increases in buoyancy and rises to engage the lifting bunks 51 with the hull
of the
watercraft 111 thereabove. Thereafter, the lifting cradle 50 carries the
watercraft
on the lifting bunks 51 upward with the lifting cradle. If the watercraft lift
10 starts
to list to the port side A, the side floats 62 on the port side A and the side
ballast
63 on the starboard side B will provide the righting moment to stabilize the
watercraft lift and prevent the watercraft 111 from rolling off of the lifting
bunks 51.
In the same manner, if the watercraft lift 10 lists to starboard side B, the
side
floats 62 on the starboard side B and the side ballast 63 on the port side A
will
provide the righting moment to stabilize the watercraft lift and prevent the
watercraft 111 from rolling off of the lifting bunks 51. This provides
increase
laterally stability for the watercraft lift 10.
8

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Figure 3 shows the watercraft lift 10 in a fully raised position with the
lifting
cradle 50 in a raised position sufficient to hold the watercraft 111 out of
the water
as shown in Figure 12. The air volume in the air tanks 40 is selected to be
sufficient that in combination with the buoyancy of the floating pontoons 60
the
watercraft 111 will be held in a raised position above the water (see Fig.
12). It is
noted that the floating pontoons 60 stay floating in the water throughout the
operation of the watercraft lift 10, and that when the lifting cradle 50 is in
the fully
raised position of Figure 3 the lifting cradle and the floating pontoons are
spaced
apart at a first distance, and when the lifting cradle is in the fully lowered
position
of Figure 1 the lifting cradle and the floating pontoons are spaced apart at a
second distance with the second distance being greater than the first
distance.
Figure 4 shows an isometric view of the air tank 40 of the watercraft lift 10.
The air tank 40 serves as the lower structural bar of a 4-bar linkage 90. The
air
tank 40 is made from a hollow rotationally molded structural plastic shell
with a
longitudinally extending, upwardly projecting, integrally formed strengthening
rib
41, laterally extending, upwardly projecting, integrally formed forward and
rearward bunk towers 48, and longitudinally extending, upwardly projecting,
integrally formed gussets 47. The rib 41 provides stiffness and rigidity, and
the
bunk towers 48 and gussets 47 distribute the load over the entire air tank
without
the need for an external structure to provide the main load support and also
would
increase the height of the lifting cradle. The air tank 40 further has a water
inlet
and outlet port 45, an air inlet and outlet port 42, an adjustable relief port
46 and
horizontally adjustable pivot points 43 and 44 using the adjustment brackets
49.
As shown in Figure 5, the lifting cradle 50 has two air tanks 40, each with
one lifting bunks 51 mounted to a top side thereof atop the bunk towers 48.
The
lifting bunks 51 is rigidly attach to the air tanks 40 on bunk towers 48 thus
adding
bending stiffness to the air tank of the lifting cradle 50. The lifting cradle
50 lifts
the watercraft 111 by introducing air through the air inlet and outlet port
42, and
thereby evacuating water within the air tank 40 through water inlet and outlet
port
45, thus increasing the buoyancy of the air tank. If watercraft lift 10 lists,
air will
escape through the adjustable relief port 46 of the air tank 40 which is the
least
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submerged, thus reducing its buoyancy and preventing the watercraft lift from
rolling. The relief port 46 comprises a column of through-holes in the wall of
the
air tank, each to be at a different height relative to the water line. The
relief port
46 is adjustable in that based on the size of the watercraft to be supported
by the
lifting cradle 50, plugs can be used to close selected ones of the through-
holes
and thereby control the ones which are operable. The adjustable relief port 46
is
provided on the laterally outward side of each of the air tanks 40. When it is
desired to lower the lifting cradle 50 to lower the watercraft 111 supported,
the air
within the air tanks is released through the air inlet and outlet port 42, and
thereby
allowing water to enter within the air tank 40 through water inlet and outlet
port 45,
thus decreasing the buoyancy of the air tank.
The air tanks 40 each include a longitudinally extending, laterally outward
projecting lower portion 40A. As best seen in Figure 12, the lifting cradle 50
is
sized so that when positioned between the floating pontoons 60, the laterally
outward projecting lower portion 40A of the port air tank 40 when the lifting
cradle
50 is in the fully raised position extends laterally outward to under the
lower side
of the port floating pontoon and engages the lower side of the port floating
pontoon, and the laterally outward projecting lower portion 40A of the
starboard
air tank 40 when the lifting cradle 50 is in the fully raised position extends
laterally
outward to under the lower side of the starboard floating pontoon and engages
the lower side of the starboard floating pontoon. With this arrangement, the
floating pontoons 60 serve as stops for the upward movement of the lifting
cradle
50. Further, the contact of the laterally outward projecting lower portions
40A of
the air tanks 40 with the lower sides of the floating pontoons 60 provides the
watercraft lift 10 with increased rigidity and stability when the lifting
cradle 50 is in
the fully raised position shown in Figure 12.
Figure 6 shows the port and starboard floating pontoons 60 without the
lifting cradle 50. Each of the floating pontoons 60 includes three side floats
62
and one forward float 61. The side floats 62 and the forward float 61 of each
floating pontoon 60 are mechanically link together with a tube 67 to which
each is
attached at its laterally inward side. The side ballast 63 is removably
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a top side of the side floats 62, and the forward ballast 64 is removably
attached
to a top side of the forward floats 61. The side ballast 63 includes heavy
concrete
tiles that provide ballast for the watercraft lift 10 as described above. The
forward
ballast 64 helps keep the watercraft lift 10 in an acceptable fore-aft
attitude in the
event air pressure within the air chambers 40 is lost or compromised and the
floating pontoons 60 must support the watercraft 111 when the watercraft lift
10 is
in a locked raised position which will be described below. The forward ballast
64
is shown as a heavy grate that covers a through opening in the forward float
61.
The through opening reduces the light blocked by the watercraft lift 10.
The side floats 62 and the forward floats 61 are constructed of a sealed
rotationally molded plastic shell with a foam filled or an air filled inner
core for
buoyancy. The buoyancy is selected to be sufficient to keep the watercraft 111
supported high enough above the water and in sufficient frictional contact
with the
lifting bunks 51 to keep the watercraft from floating off and away from the
lifting
cradle 50 when the lifting cradle is in the locked raised position even if all
air
pressure in the air tanks 40 is lost and the air tanks provide no buoyancy.
The
forward floats 61 are shaped on an inward side to accept and position the bow
of
the watercraft 111 must like a boat slip, and are designed to be used as
mirrored
parts as shown in Figure 6.
The port and starboard floating pontoons 60 are attached together at a
connection location 69 with a mechanical connection 68 which connects together
the front floats 61 of the two floating pontoons. The floating pontoons 60 can
be
split at the connection location 69 and a spacer float (not shown) can be
added
therebetween to increase the distance between the side floats 62 of the
floating
pontoons to accept a boat with a wider beam.
Figure 7 shows the swing arms 70 as having an upper pivot point 71 at an
upper end thereof and a lower pivot point 72 at the opposite lower end
thereof.
The upper end of the swing arm 70 is pivotally attached to the floating
pontoon 60
for pivotal movement relative thereto about the upper pivot point 71, and the
lower
end of the swing arm is rigidly attached to one end of the torsion bar 81 of
the
pivotal connector 80 for pivotal movement relative to the lifting cradle 50
about the
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lower pivot point 72. The pivotal connector 80 is shown in Figure 8 with one
of
the swing arms 70 rigidly attached to each of the two opposite ends of the
torsion
bar 81. As shown in Figure 7, the swing arm 70 has a substantially straight
lower
end portion with a shorter upper end portion at an angle relative to the lower
end
portion such that when the swing arm is rotated forward with the lower end
shape
aligned with a horizontal axis 73 with the upper pivot point 71 on the
horizontal
axis, the lower end portion of the of the swing arm and the lower pivot point
72 are
offsets below horizontal axis.
In Figure 9, the 4-bar linkage 90 on the port side of the watercraft lift 10
is
shown as the tube 67 of the port floating pontoon 60 being a first upper bar,
the
air tank 40 of the lifting cradle 50 being a second lower bar, and the forward
and
rearward swing arms 70 of the two pivotal connectors 80 being the third and
fourth bars. Of course, there is a similar 4-bar linkage 90 formed at each of
the
port and starboard floating pontoons 60. The upper pivot points 71 of the
swing
arms 70 are pivotally attached to the tube 67 of floating pontoons 60 at
points 91
and 92, and the lower pivot points 72 of the swing arms are pivotally attached
at
points 93 and 94 to the pivots 43 and 44 of air tanks 40 by the torsion bars
81.
The use of the 4-bar linkage 90 provides the watercraft lift 10 with a level
lift and
lowering of the watercraft 111 by the lifting cradle 50.
The adjustment brackets 49 (best seen if Fig. 4) each have an aperture
through which the end portion of the torsion bar 81 extends and in which it is
rotatably mounted. The adjustment brackets 49 are positionable during
manufacture of the watercraft lift 10 along the rib 41 of the air tank 40 to
achieve
the desired longitudinal separation between the torsion bars 81 of the fore
and aft
pivotal connectors 80 even if the molding process used for the air tank
produces a
variation in the size of the air tank from one to the other.
A lock mechanism 100 is shown in Figure 10 as being associated with one
of the swing arms 70 pivotally attached to the port floating pontoon 60 and
with
one of the swing arms pivotally attached to the starboard floating pontoon.
The
lock mechanism 100 is selectively rotatable about a vertical axis to engage
the
adjacent swing arm 70 and limit the downward movement thereof, and thus
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locking the floating pontoon 60 to the lifting cradle 50 with the lifting
cradle in the
raised position. The lock mechanism 100 includes an engagement lever 104 at
its top end, a lock shaft 101 to which the engagement lever is attached, a
lock
plate 103 for lock position indication, a load holding shoulder 105, and an
engagement foot 102. The lock mechanism 100 is mounted through one of the
side floats 62 and is bolted to the tube 67 using a clamp 106 which allows the
lock
shaft 101 to rotate therein relative to the side float. When the engagement
lever
104 is rotated into a locked position D, the lock shaft 101 is rotate about
the
vertical axis to rotate the engagement foot 102 into position below the swing
arm
70, thus limiting the downward rotational travel of the swing arm toward the
lowered position shown in Figure 1. When swing arm 70 rotates downward
sufficient to engage the engagement foot 102, the load holding shoulder 105
transfers the load placed thereon by the swing arm and the lifting cradle 50
to
which it is connected, to the side float 62 of the floating pontoon 60 through
the
clamp 106 and the tube 67. As discussed above, the ability to lock and hold
the
lifting cradle 50 in the raised position and providing the forward floats 61
and the
side floats 62 of the floating pontoons 60 with sufficient buoyancy to support
the
full weight of the watercraft 111 and keep the watercraft above the water even
should the entire air pressure in the air tanks 40 be lost, provides the
watercraft lift
10 with a significant safety feature in the event of a failure that results in
air
pressure loss in the air tanks.
When engagement lever 104 is rotated along path E to an unlocked
position C, the engagement foot 102 rotates to a position where it will not
engage
swing arm 70 and hence not limit downward rotation of the swing arm toward the
lowered position shown in Figure 1 and allow its unimpeded upward movement.
When the engagement lever 104 is rotated into the locked position D, the
lock mechanism 100 prevents accidental or unintended lowering of the
watercraft
111 into the water. Even should air pressure be released from the air tanks
40,
the locking mechanism will prevent lowering of the lifting cradle 50. When the
engagement lever 104 is rotated into the locked position D, the engagement
lever
104 may be padlocked to the lock plate 103 or in alternative embodiments
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otherwise locked to prevent rotation of the lock shaft 101 and hence rotation
of
the engagement foot 102 from under the swing arm 70. This provides protection
against theft of the watercraft 111 when on the lifting cradle 50 in the
raised
position since without being able to rotate the engagement lever to the
unlocked
position C, the lifting cradle cannot be lowered to place the watercraft in
the water,
thus preventing unauthorized removal of the watercraft from the watercraft
lift 10.
Figure 11 shows a rear view of the watercraft lift 10 in the lowered position
with the watercraft 111 in the load/unload position. The lock mechanism 100 is
in
the unlocked position C. The watercraft 111 is shown floating with respect to
a
waterline 112 and the lifting cradle 50 is submerged below and does not touch
the
watercraft 111.
Figure 12 shows a rear view of the watercraft lift 10 in the raised position
with the watercraft 111 in the stored position with the lifting bunks 51
engaging
the hull of the watercraft. The locking mechanism 100 is in the locked
position D.
The watercraft 111 rests on the lifting bunks 51 which supports it in a
position
above the waterline 102.
The floating pontoons 60 can be tied or attached to a dock, sea wall or
quay at tie points 66. The watercraft lift 10 is shown in Figure 13 in a 4-
point tie
configuration with dock lines 131 tied to a slip 132 and to the lift tie
points 66 on
the floating pontoons 60.
The watercraft lift 10 is shown in Figure 14 in a forward mounting
configuration with dock lines 141 tied to a dock 142 and the front lift tie
points 66
on the floating pontoons 60.
The watercraft lift 10 is shown in Figure 15 in a side tie configuration with
dock lines 151 tied to a dock 152 and the lift tie points 66 on the floating
pontoons
60.
The watercraft lift 10 is shown in Figure 16 with a canopy 161 mounted to
floating pontoons 60 using four canopy uprights 162.
The watercraft lift 10 is shown in Figure 17 with a hydrodynamic brake
element 171 used to control the acceleration and velocity of the raising and
lowering of the lifting cradle 50. This reduces hull impact on raising of the
lifting
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cradle 50 to provide a smooth lift. The hydrodynamic element 171 is removably
attached to the lifting cradle 50 in position between the air tanks 40 and
extends
substantially fully between the air tanks. The hydrodynamic element 102 has a
configuration selected to create increased water resistance to movement of the
lifting cradle 50 as it moves upward and downward beyond the water resistance
that would be experience otherwise. This is accomplished by the hydrodynamic
element 102 catching the water and thereby forcing the water to flow over and
around it. The hydrodynamic element 102 configuration provides water
resistance that supplements the natural water resistance experienced by the
lifting cradle 50 to control the acceleration and velocity of raising and
lowering the
lifting cradle.
A plurality of the watercraft lifts 10 are shown in Figure 18 with the
watercraft lifts mounted side-by-side. The front ends of the forward floats 61
of
the floating pontoons 60 have a straight forward portion 183 that engages a
straight side of a dock 181, and are mechanically connected to the dock. The
adjacent outward sides 182 of the floating pontoons 60 of the watercraft lifts
10
are in engagement and the adjacent floating pontoons are mechanically
connected together. In this arrangement, the watercraft lifts 10 can be used
with
a simple dock to provide a plurality of boat slips with floating wartercraft
lifts and
allows the convenient construction of a marina.
The watercraft lift 10 is shown in Figure 19 with a conduit 191 having a
length centrally routed between the floating pontoons 60 and air tanks 40. The
conduit 191 contains two air hoses. With this arrangement the conduit 191 and
the hoses contained therein are below the watercraft 111 when on the lifting
cradle 50 and hidden from view. Even when the watercraft 111 is not present,
the
conduit 191 provides an uncluttered appearance and reduces the chance of
entanglement of the air hoses with foreign objects. The conduit 191 is
corrugated
and has an elastic member arranged to keep the conduit and hence the hoses out
of the water and free from marine growth. The hoses within the conduit 191
connect to the air inlet and outlet port 42 of the air tanks 40 to provide
pressurized
air to the interior of the air tanks at sufficient pressure to evacuate the
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therein and lift the lifting cradle 50 with the watercraft 111 thereon to the
raised
position, and to allow release of the pressurized air in the air tanks for
lowering of
the lifting cradle.
The watercraft lift 10 is shown in Figure 20 with the floating pontoons 60
removed and the swing arms 70 of the pivotal connectors 80 pivotally attached
to
a slip 201 by their upper pivot points 71 at connection points 202, 203, 204
and
205. This arrangement allows the watercraft lift 10 to be converted from a
self-
supported floating lift to a lift supported by a ground supported slip as
desired.
It will be appreciated that, although specific embodiments of the invention
have been described herein for purposes of illustration, various modifications
may be made without departing from the spirit or scope of the invention.
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