GB2182289A

GB2182289A - Automatic flotation system

Info

Publication number: GB2182289A
Application number: GB08624616A
Authority: GB
Inventors: Cameron Trevor Rushton Forbes
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-10-14
Filing date: 1986-10-14
Publication date: 1987-05-13
Also published as: GB8525293D0; GB8624616D0

Abstract

A flotation system for varying the flotation characteristics of a waterborne vessel particularly a multi-hull and/or for preventing capsize, comprises a buoyance bag (13) for attachment to the hull or mast of the vessel, a source of compressed air (14), and valve means (15) responsive to a condition of the vessel, e.g. heeling towards a capsize, for controlling inflation of the buoyancy bag (13). A manually-operable air release valve 17 is provided to vent the bag to atmosphere; the bag being of bellows shape which is biased to the closed position between a base plate and outer cover by elastic straps. <IMAGE>

Description

SPECIFICATION Automatic flotation system This invention relates to an automatic flotation system intended for mounting on a waterborne vessel in order to prevent complete capsize thereof.

During adverse weather conditions or due to bad seamanship, acraftcan capsize. Forsingle (mono) hulisthe riskoftotal loss is high, and for multi hulls, re-righting the vessel is difficult when the craft overturns completely. Also, in shallow water riskofthe mast grounding and causing further damage occurs.

Accordingly it is the object of the present invention to provide a means of preventing complete overturn of a yacht or like vessel in the event of a potential capsize.

In accordance with the invention there is provided a flotation system comprising an inflatable buoyancy bag adapted for retention on a vessel in the collapsed condition, and means responsive to a condition of the vessel occurring in the event of a potential cap- size, for actuating a control valve to cause inflation of the buoyancy bag from a source of compressed gas.

Asystem according to the invention may be mounted, for example on the mast of a vessel, and/or, may also be mounted on the hulls or outriggers of a multihull vessel in order to provide controlled variation of the stability ofthe vessel in relation to the angle of heel of the hull ofthevessel.

Preferably, the means for actuating the control valve comprises a pendulum device response to tilting of a vessel beyond a predetermined limit in a direction towards the capsized position. Thus, for example, a mast-mounted device might be responsive to tilting of the mast ofthe vessel through an angle of approximately 80-90" from the vertical position, whilst devices mounted on the hulls or outriggers of a multi-hull vessel might be responsive to tilting in orderto provide controlled, partial orfull inflation within range of angles from approximately 70"-90".

The use of a buoyancy bag that is inflated only art the moment of danger of a potential capsize enables a flotation device of relatively largevolumeto be utilised, without interference with the rigging and/or handling of the craft during normal conditions. The volume of the flotation device may therefore be such as effectively to vary the flotation characteristics of the hull orto prevent the mast ofthevessel from becoming submerged inthewater, so that complete capsize of the vessel is prevented and re-righting of the hull ofthevessel is facilitated.

Additionally, manual control means may be provides to enable independent manual control ofinfla- tion.

Advantageously, means is provided for biasing the buoyancy bag to a collapsed condition whereby deflation ofthe buoyancy bag to a stand-by condition is effected automatically upon venting ofthe bag to atmosphere via an appropriate control valve.

The invention is illustrated byway of example in the accompanying drawings in which: Figure 1 is an exploded perspective view of a buoyancy bag assembly of a device in accordance with the invention, Figure 2 is a diagrammatic elevation illustrating the attachment of a system in accordance with the invention to the mast of a vessel, Figure 3 is a side view illustrating the buoyancy bag in an inflated condition, and Figures4a and 4b are diagrams illustrating the potential attachment of systems in accordance with the invention to hulls or outriggers of a multi-hull vessel.

Referring to Figure 1, a buoyancy bag assemble comprises a base plate 1 adapted for mounting to the upper region of the mast of a sailing vessel, for ex- ample by means of screw holes 1. In addition, a resin adhesive layer may be interposed between the base plate and the surface of the mast. The base plate 1 is suitably formed of pressed metal. The base plate 1 incorporates a plurality of outwardly pressed portions 3, which form loops forthe retention of elastic straps, indicated in broken lines at 4, that serve for the retention of a buoyancy bag 5 that is constructed with pleats, concentina-fashion, so thatthe buoyancy bag may be collapsed into a substantiallyflat condition as illustrated in the drawing.A moulded cover 6 shaped to enclose the collapsed buoyancy bag 5 between itself and the base plate 1 has marginal apertures 7 for receiving the elastic straps 4, wherebythe elasticstraps 4 in combination withthe base plate 1 and the cover 6 tend to bias the bag 5 into the collapsed position illustrated. An air-line 8 communicating with the interiorofthe bag is arranged to extend towards the base of the mast. The base plate 1 may incorporate a channel 9foraccommodat- ing the air-line 8.

Referring to Figure 2, the disposition of a complete system in accordance with the invention in relation to the mast a sailing vessel is indicated in via grammatic form, wherein the reference numeral 10 indicates the mastofa sailing vessel, the numeral 11 a boom associated with the mast 10 and the numeral 12 the deck of the vessel. The assembly described above with reference to Figure 1 is illustrated generally at 13, and the air-line 8 extends downwardly along the mast 10, being either exposed on the surface of the mast, or accommodated within a hollow mast. At the base of the mast is located a compressed air bottle 14which is coupledtothe air-line 8via a pressure gauge and pressure limiting valve 15, a pendulum valve 16, and an air release valve 17.

The operation of the system illustrated is as fol- lows. The pendulum valve 16 is adapted to be operated in response to tilting ofthe mast 10 into an extreme position indicating a potential capsize of the vessel, for example a position wherein the axis ofthe mast is approximately horizontal. The valve 16 may incorporate an appropriate damping device in order to ensure that actuation does not occur in response to swinging of the mast aboutthe horizontal axis in normal sailing conditions. When the valve 16 is actuated, air passes via the air-line 8 to the inflatable bag 5, in orderto distend the latter against the restor ingforceoftheelasticstraps4,theassembly13 reaching a condition as illustrated diagrammatically in Figure 3, when the bag 5 is fully inflated. The pressure limiting valve 15 ensures that theflow of airto the bag 5 ceases when the bag is in thefully inflated condition,to prevent bursting ofthe bag.In the con dition of inflation illustrated in Figure 3, the assembly 13 provides flotation that, in relation to its position on the mast 10, is sufficientto resistforces tending to submergethe mast 10,wherebythe hull ofthesailing vessel is prevented from turning over completely, and is retained in a position from which righting of the vessel can be effected, either owing to the inherent stability of the vessel, or underthe action of the occupants ofthevessel.

When the vessel has been righted, after a potential capsize as described above, the flotation system can be restored to the stand-by condition simply byventing the buoyancy bag 5 to atmosphere via the air release valve 17, so that the bag 5 is returned to its collapsed condition underthe restoring force of the elastic straps 4.

Figure 4a illustrates a typical cross-section of a multihulled vessel, the outline 20 indicating the shape of a catamaran and the broken line 21 showing the additional hull provided in the case of a tri-maran.

Figure4bisacorresponding diagrammaticper spectiveviewofthehull 22 of a tri-maran.

The reference numerals 23, 24, 25 illustrate optional mounting pointsforthe inflatable bag of a device of the general type as described above, in order to enable variation oftheflotation characteristics of the hull ofthevessel.

Subject only to weathershield/cowling and concertinashape,theprincipleformastmounting applies to hull mounting.

In the case of hull mounting an auto/manual control mechanism is used, preferably, situated in the cockpit.

Whereasthecriticalangleofmonoand multi-hulls are similar,the addition offlotation units to the seaward and hullward sides ofthe out-riggers can: 1 ) help prevent the critical angle being met (partial inflation) 2) be used as an aqua-brake - for steering control/ stability (partial) 3) by manual control, be variably adjusted to assist 1 and2(full-emerging) 4) in the event of 90 + capsize, the automatic action will inflate the appropriate port/star-board unit(s) to inflate fullyto right the vessel, or significantly assist re-righting.

(assuming an inexhaustible supply of air to the system, basic stabilisation can be achieved) As an 'average', the critical angle is 85 , and the auto-pendulum mechanism for hull mounting should be 1) partial 70-80', 2)auto80-90".

Claims

1. Aflotation system, comprising an inflatable buoyancy bag adapted for retention on a vessel in the collapsed condition, and means responsive to a condition ofthe vessel occurring in the event of a potential capsize, for actuating a control valve to cause inflation ofthe buoyancy bag from a source of compressed gas.

2. A system as claimed in Claim 1, wherein the said responsive means is arranged to respond to tilting of the vessel beyond a predetermined angle.

3. A system as claimed in any preceding claim further including manually operable air release valve meansforventing said buoyancy bag to atmosphere and means for biasing the buoyancy bag to a collapsed condition.

4. A system as claimed in Claim 3, wherein said buoyancy bag is arranged to be retained in the collapsed condition between a base plate adapted for mounting to the vessel and a cover plate connected to said base plate by means of elastic straps embracing the buoyancy bag and providing said biasing means.

5. A system as claimed in Claim 3 or 4, wherein the envelope of the buoyancy bag is of bellows or concertina-like configuration whereby it is selffolding underthe action of said biasing means.

6. Aflotation system substantially as described herein with reference to the accompanying drawings.

7. A sailing vessel incorporating a system as claimed in any one of Claims 1 - 6, wherein the said buoyancy bag is attached to the mast.

8. Awaterbornevessel incorporating a system as claimed in any one oc Claims 1 - 6, being a multi-hull vessel and having a plurality of said buoyancy bags attached to respective hulls thereof to enablevariation ofthe flotation characteristics of the vessel in relation to the angle oftilt of the hull.

9. Avessel as claimed in Claim 8, wherein theflotation system is arranged to provide forvariable inflation of said buoyancy bags within a range of angles oftilting ofthevessel.