GB2063196A - Boat drive-leg sealing arrangement - Google Patents

Abstract

The invention refers to an arrangement by which the propellor and drive- leg of a small boat engine is sealed through the hull by use of a tubular member 9 forming an integral part of the hull 6, extending downward therefrom, which encloses the engine drive- leg. <IMAGE>

Description

SPECIFICATION Boat drive-leg sealing arrangement The traditional method of fitting a motive power source in a small boat, and which is still used in many small cruisers or sailing boats, is to locate the engine approximately centrally within the length of the boat, and to connect it to the propellor by means of a shaft extending towards the stern, to the propellor located aft of the keel. This has the sole advantage that the weight of the engine, which is often heavy, is distributed by the hydraulic forces in the water along the length of the boat. The arrange ment has the disadvantage however that the engine occupies a considerable amount of the available space in the cabin area of a small boat, which is desirably required for accomodation, also there is the necessity of providing a water-seal for the propellor drive shaft, and also anti-vibration and lubrication elements.

A recent development in this field has been the introduction of the so-called 'Saildrive' principle, in which the motor, gearbox and drive unit are unified into one assembly, in which the propellor is mounted on to a leg fixed to the engine, which extends downward through a diaphragm of flexible material which provides the water seal, the weight of the entire assembly being supported upon a bearing structure sealed to the hull of the boat, within the hull, which however encloses a substantial volume of static water within the overall dimensions of the hull, this not being very desirable. This arrangement has the advantage that the engine assembly no longer occupies space within the cabin, which can thus be used wholly for accomodation.However it does have the disadvantage that the engine of conventional type will occupy a substantial space within the cockpit of a small boat, whilst the considerable weight of the engine and drive leg unit is concentrated in the stern of the boat, and therefore may well give rise to difficulties in the 'trim' of the boat, and cause it to float with stern undesirably low in the water.

It is the object of the present invention to provide an arrangement of the engine and drive-leg mounting which obviates these disadvantages, and enables full use to be made of the space available for accomodation within a boat hull of small length, for example from 5 metres to 7 metres overall length, without undue concentration of weight locally, and to enable installation of the complete power unit, in its separate parts to be carried out simply, using time-honoured techniques.

The invention will now be described in detail, referring to a number of embodiments. However these are not to be taken to represent either in part or in full the totality of the invention, which is described in full in the claims appended hereto.

In one embodiment of the invention, shown in the appended drawings, Figures 1,2, and 3, the engine which in this case is of a type which is light in weight and has the final drive shaft arranged to be vertical, shown at 1 in the drawing, is mounted on a bearing structure or series of bearers, 2, in conventional manner at the stern of the boat, within the area aft of the cabin, 3, usually in use in such small boats as a cockpit 4, in which sontrol of the boat is carried out.

The engine, 1, would be flexibly mounted on antivibration mountings, 5, in conventional manner to avoid vibration being transmitted to the boat hull, 6.

The drive leg structure, 7, would extend downward from the engine, and contain the vertical drive shaft, 8, the leg structure, 7, being located within and sealed for ingress of water into the boat by a tubular member, 9, forming an abutment integral with the boat hull. The lower end, 10, of the drive leg would enclose the final right-angle drive components, from which the propellor shaft extends substantially horizontally in the water to the rear of the boat keel, 12.

The outer structure of the drive leg would be sealed to the tubular member, 9, either in solid fashion, or through the medium of a tubular flexible member, 13, which would provide additional vibration insulation between drive leg and hull, making unnecessary any further anti-vibration mounting.

In a further embodiment of the invention, as in Figure 4, where it is desired to mount the drive leg solidly to the tubular member, 9, additional antivibration mountings, 14, would be required at the upper end of the drive leg, 7, both for the drive shaft, 8, itself, and for the torque tube enclosing it, 15, where one exists.

In the case of the embodiment described above, in which an engine with final drive shaft arranged vertically is employed, the clutch assembly, where one is fitted, and the gearbox, consisting of a train of gears to provide directional control of the boat's motion, where one is fitted, can conveniently but not necessarily be located at the lower end of the drive leg. However, if preferred, these components may be located more conveniently for some purposes be located at the upper end of the drive leg. In cases where the gearbox and clutch components are located at the lower end of the drive leg, the controls for both clutch and direction would be preferably, but not essentially brought into the interior of the boat through the tubular member.

In a further embodiment of the invention, shown in Figure 5, the engine would be of more conventional type, having final drive shatf located in a horizontal plane, 1, and would be mounted in the hull in conventional fashion, on anti-vibration mountings, 5, the power connection to the drive leg would in this case consist of a right-angle drive box, 16, which might also contain clutch and directional gear components, which would transfer power to the drive leg assembly, which would extend through a tubular member, 9, sealed into the boat hull, as in any of the previous embodiments.

In all the embodiments described above, as in other arrangements falling within the scope of the invention, it would be advantageous forthetubular member to extend within the hull of the boat to a point above the normal water-line, 17, so that in the event of a major leak of water through into the tubular member, 9, water would not gain access in large quantities to the hull. Having described the invention with respect to the embodiments described above, I claim it to be described in full in the claims listed in the separate sheet appended hereto.

Claims (10)

1. An arrangement for powering a boat, in which the engine is mounted within the hull, and the power is transmitted to the propellorthrough a drive leg, located substantially vertically in and through a tubular member forming an integral part of the hull structure, to which it is sealed in waterproof manner.

2. An arrangement as claimed in the foregoing claim, in which the drive leg is sealed to the tubular member through a solid sealing member which is waterproof but has no substantial flexibility.

3. An arrangement as claimed in Claim 1, in which the drive leg is sealed to the tubular member through the medium of a flexible tubular element which provides both waterproofing and vibration insulating properties.

4. An arrangement as claimed in any of the foregoing claims, in which the drive leg includes an element, such as a so-called torque tube, through which the reaction of the power transmitted to the propeller is withstood, which may be either internal or external to the tubular member or element, by means of which the drive leg is secured to the hull.

5. An arrangement as claimed in any of the previous claims, numbered 1 to 3, in which the reaction of the power transmitted to the propellor is withstood solely or substantially by the tubular member or element, without additional reinforcing member.

6. An arrangement as claimed in any of the foregoing claims, in which the tubular member has a circular cross-section.

7. An arrangement as claimed in any of the foregoing claims, in which the tubular member has a cross-section other than circular, or has more than one cross-sectional shape throughout its length.

8. An arrangement as claimed in any of the foregoing claims, in which the clutch and directional gear components are located at the lower end of the drive leg, and their operation is controlled by a linkage either internal or external to the tubular member or element.

9. An arrangement as claimed in any of the foregoing claims, in which anti-vibration elements are employed for either the main drive element or the torque-reaction element., or both, either within or above the tubular securing member or element.

10. Any arrangement substantially in accordance with any of the drawings attached to this application.