WO1987007231A1

WO1987007231A1 - Motor vessel

Info

Publication number: WO1987007231A1
Application number: PCT/GB1987/000350
Authority: WO
Inventors: Michael David Powell
Original assignee: Michael David Powell
Priority date: 1986-05-23
Filing date: 1987-05-21
Publication date: 1987-12-03
Also published as: AU7399587A; GB8612708D0

Abstract

A vessel for a small number of people comprises: a hull; a passenger cockpit (4) in the hull; a closable canopy (10) for the cockpit; a seat (8) in the cockpit (4); a bulkhead (6) abaft the cockpit (4); a closed engine compartment (5) abaft the bulkhead (6); an internal combustion engine (23) in the engine compartment; the vessel being self-righting by means of the centre of gravity of the loaded vessel being spaced from upper parts (4', 5') of the closed cockpit (4) and engine compartment (5), the buoyancy of which parts (4', 5') provide that the vessel is buoyant and unstable when inverted and that a substantial righting moment is present when the vessel is capsized.

Description

MOTOR VESSEL

Field of the Invention

The present invention relates to a motor vessel.

Background of the Invention

Various small speed boats exist. usually they have an open cockpit with out-board motor drive. Such boats are not suitable for rough weather, nor indeed particularly suitable for cold calm weather.

Another small, fast vessel is of the type known as a JE SKY on which the driver stands and is steadied by a handle bar structure attached to the front of the vessel. Such vessels also are not really suitable for other than warm, calm weather.

It is well known that stability is provided in a vessel by arranging for the centre of gravity to be below the centre of flotation in an inherently stable configuration or above the centre of flotation in a meta-stable configuration for which the hull shape is such that the centre of flotation displaces in the direction of heel to provide a righting moment. In a typical stable vessel, buoyancy can decrease due to ingress of water on capsize, and sinking can result. Self-righting vessels are known in which non-floodable buoyancy remains greater than the weight of the vessel in water and so arranged with resgect to the centre of gravity of the vessel to return the vessel at least partially upright following capsize. Such a vessel is described in British Patent Specification No. 1,404,191.

The Invention

The motor vessel of the present invention has been designed as a high-speed , self-righting boat for use in a wide range of weather and sea conditions , as experienced for instance around the British Isles, although the vessel will be suitable for use in warmer climates.

According to the invention there is provided a vessel for a small number of people comprising:- a hull, the hull having a single passenger cockpit and 5 providing normal buoyancy; an inboard motor mounted in the hull behind the cockpit; at least one seat mounted in the cockpit forward of the motor; additional, self-righting buoyancy means arranged to be 10. normally above the higher of the vessel's normal water line and the vessel's centre of gravity when floating normally with the seat(s) occupied and to cause the vessel to float unstably when the vessel is inverted with its centre of gravity above the vessel's inverted centre of flotation. 15. Whilst it is envisaged that seats for a few more people may be provided, the preferred number is one or two.

It is envisaged that the additional self-righting buoyancy may be provided in the form of a suitably positioned sealed space or volume of cellular material. However in 20 the preferred form, the buoyancy is provided as at least part of at least one substantially closed or closable compart¬ ment. The self-righting buoyancy may be provided as a single compartment, either separate from or in conjunction with the cockpit - containing the seat(s) . Where a separate 25 buoyancy compartment is provided, it conveniently houses the motor and is divided from tne cockpit by a bulkhead. The buoyancy compartment can conveniently be constructed as superstructure integral with the hull.

It should be noted that it is not necessary to provide 0 a physical partition between a lower normal buoyancy part of the compartment and an upper self-righting buoyancy part of the compartment.

The cockpit may be open with a windscreen. However it is preferably provided with a substantially water-tight 5 canopy, in which case, the cockpit can provide some or all of the self-righting buoyancy.

The motor is preferably an internal combustion engine. » In the preferred embodiment, the cockpit has a canopy and is divided by a bulkhead from a self-rightingly buoyant 5 engine compartment. The air intake for the engine may be direct to the engine compartment. However, to provide ventilation to the cockpit, an air intake is preferably provided to the cockpit, with a transfer aperture being provided in the bulkhead. To provide forced ventilation,

10 when the engine is not running - and drawing in air - a separate ventilation fan may be provided, conveniently in trunking leading from the aperture. With this arrangement, an air outlet from the engine compartment is provided. The air inlet, the air outlet and the bulkhead aperture are

15 preferably all provided with trunking from their positions above the vessel's normal waterline to above the expected waterline in the inverted position of the vessel from which the vessel will self-right. This trunking prevents the cockpit and the engine compartment from filling with water

20 when the vessel is inverted. The fan preferably has a high volume/low pressure configuration. Alternatively the fan may automatically de-activate when inverted. To enable the engine to keep running when inverted, a supplementary air inlet/outlet is provided in the engine compartment close

25 above the normal water line. Conveniently, it is connected by trunking to the air outlet. The inlet to this trunking is close to the supplementary air inlet and leads from the top of the engine compartment to purge it of the hot vapours accumulating there.

30 The engine conveniently drives the vessel via a jet _jr drive, whereby the vessel can have a very shallow draught.

For landing on a beach or ramp, the vessel may be provided * with bottom runners or wheels.

To provide good handling characteristics, the vessel

35 preferably has a beam stepped inwards at a false transom in the region of the engine.

In order to help understanding of the invention, a specific embodiment thereof will now be described by way of example and with reference to the accompanying drawings.

The Drawings

Figure 1 is a diagrammatic, central longitudinal cross- sectional view of the vessel;

Figure 2 is a side view as Figure 1 of the vessel floating normally;

Figure 3 is a view similar to Figure 2 of the vessel floating inverted;

Figure 4 is a rear view of the vessel floating normally;

Figure 5 is a rear view of the vessel floating on its side in a transient position;

Figure 6 is a rear view of the vessel floating inverted in an unstable position; and

Figure 7 is a plan view of the vessel.

The Preferred Embodiment

The vessel 1 has a forward water-tight compartment 2 divided by a water-tight bulkhead 3 from a cockpit 4 itself divided from an engine compartment 5 by a water-tight bulkhead 6. It should be understood that although both bulkheads 3,6 are water-tightly sealed to the hull 7, they have a number of passages therethrough for in particular ventilation as described below, fuel and bilge pump lines etc. The hull 7 and the bulkheads 3,6 are of glass rein¬ forced plastics material. The cockpit 4 has a seat 8 for one or two people and side lockers 9 arranged as arm rests. The cockpit 4 is of such length that the forward bulkhead 3 serves as a foot rest whilst the rear bulkhead is immediately behind the driver's head. The aft bulkhead 6 extends above the seat 8 so that a half-elongate-dome acrylic canopy 10 covering the cockpit 4 meets with its rear vertical edge this bulkhead. The forward end of the canopy has a follower 11 running on a » track 12 arranged centrally on a fore deck 13 over the forward part of the cockpit 4. When the canopy is run 5 forward, under the guidance of the follower on the track, the driver can enter or leave the cockpit. When the canopy is slid back, its aft corners can be clipped via clips 14 to the hull, so as to bring the canopy into sealing contact with a seal 15 extending around the bottom of the canopy and

10 up its rear vertical edge. Thus the cockpit is sealed against ingress of water at the canopy.

Immediately to one side of the track 12, a cowled air inlet 16 is provided in the fore deck above the forward part of the cockpit. Its cowl permits air to enter the inlet

15 only at an air intake 17 on its after side. A trunking 18 leads from the inlet 16 to the bottom of the cockpit, to prevent water entering the cockpit from the inlet 17 when the vessel is floating inverted - as described below. The outlet 19 of the trunking is below the driver's legs. From

20 it air flows up past the driver to an aperture 20 in the bulkhead 6 above and behind the driver's head. This in turn is connected to trunking 21 in the engine compartment leading via an electrically powered blower 22 to the bottom of the compartment 5, to prevent water entering the engine

25 compartment should the canopy seal 15 leak, when the vessel is floating inverted. When the water-cooled two-stroke engine 23 is not running - for instance the blower 22 remains running for a short while after the engine is cut out - or it is consuming at its carburettor 23' less air

30 than is blown by the fan, air is blown out of the engine jr compartment 5 via outlet trunking 24 positioned at the top of the compartment to scavenge hot gases and vapours. The * trunking 24 leads to either of two outlets 25,26 in the hull. These are interconnected by a trunking branch 27.

35 One outlet 25 is positioned high in the rear wall 28 of the engine compartment so as to be well clear of the waterline. Here it is immersed when the vessel is floating inverted; thus to avoid then ingress of water the trunking 24 is joined to the trunking 27 at a point normally above the waterline when the vessel is inverted. In this condition, the engine will remain operational and draws air from outlet 26 which is above the normal use waterline and the inverted waterline; thus decompression. of the cockpit/engine com¬ partment is avoided. It is possible when the engine is at full throttle that it may draw air in at the outlets 25,26. In Figures 2 and 3, the centre of gravity of the vessel including the driver (and passenger for a two man vessel) is shown at 29, whilst the centre of flotation when the vessel is inverted is shown at 30. The separation of these centres 29,30 and the hull shape is such that inverted floating is unstable and thus the vessel is self-righting.

Figures 4 to 6 as rear views show the vessel's stability and self-righting characteristics more clearly. Figure 4 shows the vessel's normal stable floating position. Figure 5 shows the capsize position in which, whilst the centre of gravity obviously remains fixed in the vessel, the centre of flotation 30' is substantially displaced from below the centre of gravity that a substantial righting moment is present. The hull, including the cockpit, being closed except for the ventilation in- and out-lets, no substantial ingress of water occurs to shift the centre of gravity. The water displacement giving rise to the buoyancy having the centre of flotation 30' is comprised in part of normal hull displacement and in part of self-righting buoyancy - i.e. the upper part 4' of the cockpit 4 and the upper part

5' of the engine compartment 5. Figure 6 shows the unstable inverted position in which the buoyancy having the centre of flotation 30 is comprised entirely of self-righting buoyancy in the "upper" part 4' of both the cockpit 4 and the upper- part 5' of the engine compartment 5. Although no righting moment is present in the Figure 6 position, wave action or rolling momentum of the vessel will disturb the unstable equilibrium shown in the Figure and the vessel will roll back upright. Capsize or inversion of the vessel is not expected to be a regular occurrence but one which must be accommodated with a closed canopy vessel such as this in order to not compromise its seaworthiness. On inversion, water will enter the trunking 18 and the trunking 27. On righting, the water in the former flows into the cockpit bilge and is pumped away through line 31. The water in the latter trunking 27 flows out through the outlet 26. In case of leakage, as occurs in most vessels, the engine compartment bilge is pumped out via line 32. Both lines 31,32 are connected to a venturi pump operated by the water jet propulsion unit 33. This has a steerable nozzle 33' mounted on the rear transom 34 immediately above the transom foot 35. The propulsion unit draws water from a central, bottom slot 36. The hull is shown in plan in Figure 7 and has a false transom 37, ahead of the intake slot 36, whereby the hull is broader in the beam at the cockpit than at most of the engine compartment. This hull form gives:- i) a comparatively long hull for economic slow speed operation; ii) stable planing at medium speeds with the false transom foot 38 and hull bottom immediately ahead of it in the water, on account of the centre of gravity being close in front of the centre of pressure enabling the vessel to start planing readily and of the rear hull extension 39 lift component 40 tending to trim the bow of the vessel down; iii) high speed capability with the intake 36 slot completely immersed - in calm conditions - due to planing on the smaller beam rear hull extension 39 alone. Despite the stepped hull, it is not too broad to prevent self-righting.

Claims

CL IMS

1. A vessel for a small number of people comprising:- a hull, the hull having a single passenger cockpit (4) and providing normal buoyancy; an inboard motor (23) mounted in the hull behind the cockpit (4) ; at least one seat (8) mounted in the cockpit (4) forward of the motor (23) ; and additional, self-righting buoyancy means (4' ,5') arranged to be normally above the higher of the vessel's normal water line and the vessel's centre of gravity (29) when floating normally with the seat(s) (8) occupied and to cause the vessel (1) to float unstably when the vessel (1) is inverted with its centre of gravity (29) above the vessel's inverted centre of flotation (30) .

2. A vessel as claimed in claim 1, wherein the additional, self-righting buoyancy means comprises an upper part (5') of a motor compartment (5).

3. A vessel as claimed in claim 2, wherein a watertight bulkhead (6) divides the motor compartment (5) from the cockpit (4) .

4. A vessel as claimed in claim 1, claim 2 or claim 3 wherein the cockpit (4) has a canopy (10) and the additional ^' self-righting buoyancy means comprises an upper part (4*) of the cockpit (4) within the canopy (10) .

5. A vessel as claimed in claim 4 as appendant to claim 3, wherein the motor (23) is an internal combustion engine (23) and including air intake means (17,18,19,20,21,22) for passing air via the cockpit (4) to the engine (23) .

6. A vessel as claimed in claim 5, the air intake means comprising an air intake (17) on the fore-deck in communication with trunking (18) and an air outlet (19) at the bottom of the cockpit (4) , and an air aperture (20) through the top of the bulkhead (6) in communication with trunking (21) leading to the bottom of the engine compartment (5) , the arrangement being such that water does not pass into the cockpit (4) nor the engine compartment (5) on inversion of the vessel (1) .

7. A vessel as claimed in claim 6, including a high volume/low pressure air blower (22) in the trunking (21) for ventilating the cockpit at low engine speed.

8. A vessel as claimed in claim 7, including an engine compartment scavenging/supplementary air inlet arrangement comprising a trunking (24) passing from the top of the engine compartment (5) to ambient.

9. A vessel as claimed in claim 8, wherein the trunking (24,27) branches at a point above the vessel's expected water line when inverted, one branch passing out (25) of the engine compartment above this water line and the other branch passing out (26) below this water line.

10. A vessel as claimed in any preceding claim, wherein the motor (23) drives a water jet propulsion unit (33).

11. A vessel as claimed in claim 2 and any one of claims 3 to 10 as appendant to claim 2, wherein the hull has a false transom (37) positioned at the motor compartment (5).

12. A vessel for a small number of people comprising:- a hull; a passenger cockpit (4) in the hull; a closeable canopy (10) for the cockpit; a seat (8) in the cockpit (4) ; a bulkhead (6) abaft the cockpit (4) ; a closed engine compartment (5) abaft the bulkhead (6) ; an internal combustioh engine (23) in the engine compartment; the vessel being self-righting by means of the centre of gravity of the loaded vessel being spaced from upper parts (4' ,5') of the closed cockpit (4) and engine compartment (5), the buoyancy of which parts (4' ,5*) provide that the vessel is buoyant and unstable when inverted and that a substantial righting moment is present when the vessel is capsized; the vessel further comprising:- engine air supply means including trunking (18) from an air inlet (16) on a foredeck (13) to a lower part of the cockpit (4) and trunking (21) from an aperture (20) at the top of the bulkhead to a lower part of the engine compartment whereby neither the cockpit (4) nor the engine compartment (5) floods on vessel inversion; and supplementary air intake means having a first inlet (25) in an engine compartment wall below the expected inverted water line, a second inlet (26) above the said water line and a. Tee junction to a supplementary air trunking at the top of the engine compartment (5) .