Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
This i.nvention relates to elongated buoyant marine devices,
the displacement of which decreases during operation as a result of
weight loss, suc.h as pyrotechnic marine markers. The invention
relates more partlculary to improved devices of this type which are
more capable of retaining proper operative orientation during thei.r
functioning.
Marine markers are frequently used as signalling devices
for example they may be displayed in conjunction with sonobuoys by
long range marine patrolaircraft during anti-submarine operations.
They may also be used for search and rescue operations, for example
to mark a wreckage site, or to mark a position at sea (icefloes, oil
slicks). These markers are designed to produce smoke and an intense
flame, generally by the burning of a pyrotechnic candle or flare.
The flare ls usually enclosed in an elongated jacket, and for example
may consist predominately of red phosphorus which produces dense
white smoke and a yellow flame for a period of thirteen to nineteen
minutes from time of ignition by a salt water-ac.tivated battery and
squib combination. Although the marker initially floats vertically in
the water, the increase in buoyancy after several minutes of burning
causes it to cant until, as the burning continues, the marker usually
finally ceases burning in an almost horizontal position on the
surface of the waterO In other words, because the weight of the
marker decreases as the flare burns, its displacement is greater at
the beginning of its operation than at the end. As burning continues
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the marker gradually rises in the water and slowly begins to tip as
the burning progresses until, at a time for example halfway through
the burn time, it reaches an almost horizontal position which it
retains until the end of the burn.
In this final position the combustion gas outlet at the
top of the marker is nearer the water than when the marker i.s in a
vertical positionO The marker may thus be more easily submerged by
waves; water pel~etrating the marker through the gas outlet can hamper
the operation of the marker and cause the flare to.burn inter-
mittently or incompletely.
Under ideal burn conditions, for example in calm water
where the problem of water penetrating the marker does not arise, the
marker will burn continuously for the speclfic period for which ~t
was desi.gned. In practice however ideal conditions do not prevail
and because the markers may burn inter~littently or incompletely, it
follows that, to obtain effective production of fiame and smoke for a
given time, a greater number of markers must be used than would be
required under ideal burn conditions.
Some marine devices have a flotation collar fitted around
their upper part to ensure that the device re~ains in an upright
position while it operates. Flotation collars are made of a mbber-
like material which inflates when the devlce enters the water, or of
a buoyant material such as foam rubber or the like. Such flotation
collars significantly increase the size and cost of such devices.
AccordLngly it i~ an object of the present invention to
provide an effective, more economical construction for such marine
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markers and other elongated buoyant marine devices, the disp:Lacement
of which decreases during operation as a result of weight loss, whlch
will be effective in maintainlng the device in a vertical, or close-
to-vertical, operative position.
SIJM~ARY OF THE INVENTION
In accordance with the present invention, there is provided
in such an elongated buoyant marine device having an operative
section enclosed by a ~acket a ballast means enclosed by the ~acket,
and means to enable the ballast compartment to progresslvely fill
with water. During operation, displacement of water by the device is
maintained to a degree which will ensure that the device remains in
an operative orientation.
The invention may be incorporated for example in an elon-
gated buoyant pyrotechnic marine marker, which marker comprises a
pyrotechnic candle, ignition means for the candle 9 and a ~acket en-
closing the candle and ignition means, the ~acket havlng a smoke or
flame emission hole for the release of smoke or flame produced by the
candle when ignited. The marker is provided with a ballast com-
partment, situated at all ti~es below the centre of gravity when the
marker is burrllng in its normal operative orientation. The marker is
I ~provided with one or more water inlet ports in the ballast compart-
ment to enable water to enter the ballast compartment. The marker is
~also provided with one or more air exhaust ports in the ballast com-
partment to permit escape of air from the compartment as water is
taken on by the ballast compartment. The inlet and outlet ports are
of a size to control the filling of the ballast compartment by water
so that this filling of the ballast compartment takes place over much
of the time during which the marker operates, and hence at a rate so
as to compensate for the progresslve weight loss of the burning
pyrotechnic snaterial. The water inlet ports and air exhaust ports,
in a simple5 straightforward version of the invention, comprise holes
formed in the jacket of the marker, the jacket forming the outer wall
of the ballast compartment.
By ensuring that the volume of the ballast means is such
that the weight of water enterlng it increases the weight of the
marker by not less than a predetermined percentage of the total
weight lost by the marker during operation, the marker is held in a
vertical or nearly vertical orientation during operation. It has
been ~ound that such markers operate effectively when they are held
to no greater than a 20 deviation from vertical. With markers of
the shape and construction now in use, it has been found that a
volume of ballast means such that the weight of water entering it
increases ,he weight of the marker by not less than 30% of the total
weight lost by the marker results in an e~fective construction and
operation of such a markerc This figure of 30% however is quite
arbitrary and in general will depend on the configuration and mass of
the marker as well as the location of the ballast compartment
relative to the centre of gravity.
~RIEF DESCRIPTION O~ THE DR WINGS
Other ob~ects and advantages of the invention will become
apparent upon reading the following detailed description and upon
referring to Figure 1 which is a side view, in section, of an
exemplary marine marker according to the present invention.
While the invention will be described in connectlon with
specific embodiment, it will be understood that it is not intended to
limit the invention to that embodiment. On the contrary it is
intended to cover all alternatives, modifications and equivalents as
may be included within ~he spiri~ and scope of the invention as
defined by the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
.
Turning to Figure 1 there is shown an elongated buoyant
marine marker 2 of the pyrotechnic type having pyrotechnic candle 4
and ignition means 6 activated by salt water. The entire device is
enclosed by jacket 8. Jacke~ 8 is filled with an appropriate
closed-cell foam material 13 ~o provide buoyancy and is reinforced by
s~iffeners lOo
Ballast compartmen~ 12 is provided at the bottom end of the
marker, the lower portion of jacket 8 cons~itu~ing the outer wall
thereof. Water inlet port 14 and air outlet port 16 are provided in
that part of jacket 8 which constitu~es ~he outer wall of ballast
compartment 12.
For the water in which the device is floating to enter
ballast compartment 12 gradually throughout ~he burn period of candle
4, the inlet port or por~s 14 must be of a specific size. As
indicated on the figure, a minimum of t~o ports are required, the top
port 16 to allow air from compartment 12 to be released through the
upper part thereof as water is taken on.
~ hile no~ shown, the ballast compartment incorporated in
the marine marker can be of any shape (cylindrical, ring-shaped,
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etc.); it is also to be understood that, while not illustrated, two
or more ballast compartments, interconnected or not, and of slmilar
or of different shape, may be incorporated in the marine marker to
keep it in its vertical position while it is opera-ting. The
compartment or compartments must be situated at all times below the
centre of gravity when the marker is burning in its normal operative
orientation.
The total volume of the compartment (or compartments)
should be such that the weight of the water penetrating it (or them)
to increase the weight of the marker, corresponds to nol; less than
~ 30% of the total weight lost by the marker during operation~ This
ensures a counterbalancing weight capable of holding the marker in a
vertical or nearly vertical position (preferably not more than 20
from the vertical position) throughout its operation.
For the cylindrical marine marker illustrated in the
accompanying figure9 the burn time is about 18 minutes, the overall
length 53 cm, diameter 12.4 cm, initial total mass 5.3 kg, and
initial mass of the flare 3~9 kg. The volume of the ring-shaped
ballast compartment is 0.73 1 and corresponds to about 12% of the
total volume of the marker, 6.41 1. During operation, the mass of
the water entering this compartment accounts for some 52% of the mass
lost by the marker, 1.4 kg~ through burning of the flare. The
diameter of the two port holes~ 0.17 cm, ensures a gradual intake of
water into the compartment throughout the operation of the marker.
The overall net weight loss of the marker during its burn causes it
to rise up slightly in the water; some 14 cm of the marker is exposed
" ~,
~,
above the water's surface at the end of burn as compared to 8 cm at
the the commencement oE E~mctioning. This rising of the marker
results in :Lts tilting approximately 10 from the vertical
orientation.
Thus it is apparent that there has been described in
ac.cordance with the invention an elongated buoyant marine marker that
fully satisfies the ob~ects, aims and advantages set forth above.
While the invention has been described in conjunction with a specific
emhodiment thereof, it is evident that many alternatives,
modifications and variations will be apparent to those skilled in the
art in light of the foregoing description. Accordingly~ i.t is
intended to embrace all such alternatives, modifications and
variations as fall within the spirit and broad scope of the appended
claims~
