Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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2.
FLOATING BREAKWATER
This invention relates to a floating breakwater suitable for
use in harbors for inhibiting wave action thereby providing a
sheltered mooring location for boats and the like.
Floating breakwaters are mooring structures that float at or
near the water surface and cause incident wave energy to be
dissipated by reflectlon, turbulenae, drag, damping or other
suitable means thereby causing wave heights to be reduced on the
leeward slde.
Conventional floating breakwaters for the above mentioned
purpose have included one type formed by a multiplicity of
floating tires linked together by chain links, poles or rope and
which are designed to cover a relatively large area. While such
floating breakwaters have been found to be relatively inexpensive
lt has also been found that they require a high degree of
maintenance and are also particularly susceptible to storm
damage.
Another type of floating breakwater includes the use o
large rectangular or doughnut shaped concrete pontoons arranged
in single rows or double parallel rows to present a
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fla-t or planar surface to wave action. rrhe pontoons were
normally anchored with pil0s or moored to anchor blocks with
chains or rope. However, it has been found if the wave heights
exceeded three feet the use of concrete pontoons was
disadvantageous because the articulated joints between the
pontoons were highly stressed and often were broken. I'hus
failure of the articulated joints was common.
In addition to the aforementioned disadvantages the
conventional floating breakwaters as described above were su'bject
to unsatisfactory performance in regard to insufficient
attenuation of transmltted waves. Also structural failures and
mooring failures were common.
It is the ob~ect of the invention to provide a floating
breakwater which alleviates the problems of conven-tional floating
breakwaters described above.
Briefly stated, the invention involves a breakwater
comprising a continuous block formed by a plurality of modules, a
rear block in-terconnection strip contacting each rear surface of
the modules of said continous block and a fron-t block
interconnection strip contacting each front surface of the
modules of said continuous block, a plurality of spaced apart
fingers disposed in engagement with said front block
interconnection strip and e~tending outwardly away from said
continous block, a continuous finger interconnection strip
contacting the front surface of each of said fingers and an
elongate beam secured between each pair of adjacent modules and
extending outwardly from said continous block in spaced parallel
relation to said fingers and means securing the beam to said
continuous block to strengthen the breakwater.
In another aspect of the present invention there is provided
a breakwater comprising a rear continuous block formed by a
plurality of modules in abutting relation wherein each module has
an internal sheath formed from floatable material and an external
core formed from concrete, a rear block interconnection strip
contacting each rear surface of said module of said continuous
block and a front block interconnection strip contacting each
front surface of said modules of said continuous block, a first
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plurality of elonga-ted fasteners extending through and
interconnecting said modules and said front and rear block
interconnection strips, a plurality of spaced apart fingers each
having a construction similar to the construction of each module
disposed in engagement with said front block interconnection
strip and extending outwardly away from said rear continuous
block, a continuous finger interconnection strip contacting the
front surface of each of said fingers and a second plurality of
elongated fasteners extending through and interconneoting said
strips, said fingers, and said rear continuous bloc~.
Preferably each module may be formed in a mold which
initially supports the internal ~ore by wedges or the like so
that the core is spaced from the inner surface of the mold.
Thereafter a metal (usually steel or iron) reinforcing mesh may
be located on top of the internal core and a plurallty of -tubes
formed suitably from plasticæ material interposad between the
internal core and the reinforcing mesh. Thereafter concrete may
be poured into the mold so as to fill up the space between the
internal core and the inner surface thereof. Thereafter concrete
may be poured onto the top surface of the internal core so as to
form a top wall of the module enclosing the reinforcing mesh and
a plurality of tubes formed from plastics material.
The breakwater may also include a plurality of outwardly
extanding fingers or projections which preferably are equally
spaced along the length of the continuous block. The fingers may
be attached to the continuous block in any suitable manner such
as by elonga-te fasteners such as through bolts extending through
the rear continuous block and the length of each finger. It is
also preferred that the spaces between adjacent fingers are
approximately equal to the width of the fingers.
The fingers again may be formed in modules or standard
shapes or lengths and if desired may comprise a similar shape to
the modules comprising the continuous block. Preferably the
con-tinuous block is rectangular but this is not essen-tial.
There also may be provided a front interconnection strip or
beam which is orien-ted substantially parallel to the
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interconnection strips described above in regard to the rear
continuous block.
It is also desirable that there be provided a plurality of
transverse beams which interconnect the front interconnection
strip and which may extend rearwardly of the rear continuous
block and which may also be suitably attached to both of the
interconnection strips associated wit~h the rear continuous block.
In this embodiment each transverse beam may extend from the front
interconnection strip and be interposed between adjacent fingers
so that the transverse beam may also extend between adjacent
modules of the rear continuous block.
The provision of the aforementioned transverse beams is
advantageous in that they enable the ~loating breakwater to have
a stiffening function and thus inhibit movement of the fingers
relative to the rear continuous block. Without the transverse
beams it is possible for the fingers to move up and down or
undergo vertical oscillations relative to -the rear continuous
block under wave action.
The foregoing and other objects, features and adva~tages of
the invention will be apparent from the following more particular
description of a preferred embodiment of the invention given by
way of example only as illustrated in the accompanying drawings.
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6.
Figure 1 is a perspective view of a floating break~ater
constructed in accordance with the present invention.
Figure 2 is a front view of the breakwater shown in
Figure 1.
Figure 3 is a plan view of the breakwater shown in
Figure 1.
Figure 4 is a front perspective view of a modified float~
ing breakwater constructed in accordance with the invention.
Figure 5 is a rear perspective.vie of the floating break-
water shown in Figure 4.
Figure 6 is a plan view of the floating breakwater shown
in Figure 4.
Figure 7 is a front view of the floating breakwater shown
in Figure 4.
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7.
The breakwater 10 in the drawings includes a rear continuous
block 11 formed by a plurality of ad~acent modules 12 which may
be formed as described above and which are all manufactured in
standard lengths. There is also shown opposed timber
interconnectlon strips or whalers 13 which are located on the
front and rear slde of block 11 and which are attached thereto by
bolts 14.
Also shown are outwardly e~tending fingers or proJections 15
which may be formed in standard lengths simllar or di~ferent to
modules 12. Also shown ls a front lnterconnection strlp or
whaler 16 attached to ~ingers 15 by bolts 14. The fingers 15 may
also be formed with plastics internal tubes 16A as is the case
with modules 12 in the manner described above which may be
aligned or oriented wlth each other so as to facilitate the
insertion of connection bolts 14 to attach the fingers 15 to
block 11. Each module 12 may have an internal core of foam
material 17 and an outer shsath of concrete 18. Included in a
top wall or layer 23 of sheath 18 are the plastios tubes 16A and
reinforcing mesh 22. Located between each finger are recesses
19 .
It will be appreciated that the fingers 15 may be oriented
to the longitudinal axis of block 11 at any appropriate angle
suitably between five degrees and fifteen degrees for exampleO
However it is preferred that fingers 15 extend at right angles to
the longitudinal axis of block 11.
The floating breakwater of the invention may be anchored by
any suitable means such as by a rope (preferably formed from
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8.
nylon) or chain to a stub pile driving into the ground or a heavy
waight. Alternatively for more shallow water the breakwater may
have attached thereto appropriate support brackets which have
rollers angageable in appropriata tracks in anchor piles driven
into the ground.
The essence of the invention .is based upon the discovery
that by the establishment of a rear continuous block and
frontwardly extending fin~ers that the impact of the waves will
be broken upon impingement upon the fron-t surfaces 20 of fingers
15 and that when the waves extend into the recesses 19 that they
will also implnge upon the opposed side surfaces 21 of recesses
19 so as to form an interference pattern which will result in at
least partial cancellati.on o~ the wave trains created. This
provides a simple and very effective breakwater system.
It will also be appreciated that the fingers 15 instead of
being rectangular as illustrated may adopt any other convenient
shape such as trapezoidal, triangular or polygonal. However the
rectangular shape is preferred for ease of manufacture. Also the
fingers 15 do not have to have the same length as illustrated but
may have different lengths if re~uired.
Also in variation of the above, the through bolts may extend
longitudinally of the block 11 instead of transversely as shown
and the fingers 15 may be attached to the block 11 in any other
suitable manner such as by welding of adjacent metal plates or by
bolting together ad~acent attachment brackets.
In the modified arrangement as shown in Figures 4-7 there is
shown a rear continuous block formed by modules 12A which
9.
are each separa-ted by transverse beams 24, which are attached to
front strip 1.6 at 25, -to a pair of intermedlate strips 13A at 26
and to a rear strip 13A at 27.
As best shown in Figure 5 each transverse beam 24 extends in
recesses 29 which are ~ormed between abutting modules 12A as
shown. In this arrangement each module 12A is provided with a
pair of side flanges 28 which abut as shown above an adJacent
recess 29.
In Figure 6, instead of through bolts 14 each extending
through adjacent modules 12 and 15 as shown in Figures 1-3, it is
also appropriate in some cases to use separate through bolts
wherein through bolts 14A may be used to interconnect rear strip
13A and intermediate strip 13A through modules 12A and through
bolts 14B may be used to interaonnect ront strip 16 and one of
the intermediate strips 13A. Thus through bolts 14A and 14B do
not connect with each other in the embodiment shown in Figure 6.
Also as best shown in figures 6-7, it is preferred that the
width of fingers 15A are approximately e~ual to the spacing 19
between individual fingers 15A.
In the arrangement shown in Figures 4-7 the floatlng
breakwater shown is a rigid structure and both the fingers 12A
and modules 15A are inhibited from relative movement especially
by the incorporation of beams 24.
The provision of the front strip 16 is mainly responsible
for causing wave turbulence and in tests carried out with a full
scale prototype strip 16 caused approximately fifty percent of
any wave front higher than 15 inches to break and spill over the
strip 16 into spaces 19 thus causing a high degree of
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turbulence. Spaces lg also promote turbulence as also is the
case with beams 24.
In regard -to reflection of waves in relation to waves
incident on the floating breakwater at ninety degrees such waves
were ~ound to be reflected by the outer fingers 15A, strip 16 and
the rear continuous block ~ormed by modules 12A. In relation to
wave incidence at angles other than ninety degrees re1ection of
these waves occurred through the agency of end surfaces 20 of
~ingers 15A, side surfaces 30 of fingers 15A, beams 24 and the
rear continuous block.
In regard to the relatively lars~e surface area exposed to
the water by the present invention, especially in comparison with
the a~orementioned conventional concrete pontoons it was noticed
that a drag effect was obta~ned which was previously only
obtainable with the aforementioned conventional breakwaters
formad by a mul-tiplicity of floating tires.
A damping effect was also obtained which could be attributed
to the mass of the total structure and in particular the rear
continuous block.
Other advantages obtainabls by the floating breakwater o~
the invention are set out below.
Response: Because the buoyancy of the outward extended ~ingers
is approximately fifty percent less than the rear continuous
block the whole structure does not oscillate about its
longitudinal axis as is common with other concrete pontoon
floating breakwaters. ~n oscillation of this type tends to allow
waves to pass through the breakwater.
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Moorin~ Forces: The staggered profile presented to the lncoming
waves reduces the forces on the moorings. If the outward
extending fingers are so dimensioned to have a length equivalent
to a half wave length the pressure forces are out of place by one
hundred degrees.
Cost: As all components used for the present invention can be
"off the shelf" items in normal use for the construction of
regular floating marinas, the cost o~ this breakwater is minlmal.
Maintenance: The concrete encased pontoon type floating marinas
have proven to reguire minimal maintenan~e and as the
construction of the presant invention is similar the maintenance
of this inventlon will also be minimal.
Damage: As there are no articulated ~oints and the whole
structure has a controlled flexibility, the power to withstand
storm damage of the present invention is better than other
floating breakwaters in use.
Combination Floating Breakwater and Marina Berths: Because the
structure of the present invention can be made from regular
pontoons, the rear continuous block can have regular fingers
attached on the leeward side to form marina berths. This further
improves the performance of the structure as a wave attenuator
and also reduces overall costs of marina berths. The seaward
side of the ~loating brea~water can also be used for temporary
mooring of boats during calm water periods.
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It will also be appreciated that a plurality of front
strips 16 may be used instead of the single strip illustrated
and the same applies for intermediate strips 13 or 13A and rear
strips 13 or 13A. It also will be appreciated that a plurality
of beams 24 may also be utilized which may extend through a
respective spacing 19.
While the invention has been particularly shown and
described with reference to preferred embodiments thereof it
will be understood by those in the art that the foregoing and
other changes in form and details may be made therein without
departing from the spirit and scope of the invention.
