Mount for a boat propulsion unit

Abstract

A mount for a boat propulsion unit comprises a collar for mounting around an aperture in a boat's hull, the collar having an annular groove on an inner surface thereof; a first mating part for mounting an inboard portion of a propulsion unit to the boat; and a second mating part, connectable to the first mating part, for mounting an outboard portion of a propulsion unit to the boat. The first and second mating parts are connectable through the collar and are configured such that when they are connected they form an external annular recess in an outer surface and an annular gasket is located partly in the groove and partly in the recess to form a seal there-between.

Description

FIELD OF THE INVENTION[0001]This invention relates to a mount for a boat propulsion unit. Particularly, but not exclusively, the invention relates to a mount for mounting an inboard propulsion unit in a boat hull.BACKGROUND TO THE INVENTION[0002]Aspects of the present invention are particularly concerned with the mounting of electric propulsion units that consist of a saildrive projecting from the bottom of a boat's hull and that have an inboard motor mounted above the saildrive. In essence, a saildrive can be considered as a sailboat's equivalent of a motorboat's sterndrive, which projects from the stern of a boat and usually has a drive mounted outside of the hull (and is therefore also known as an outdrive). A saildrive is significantly different to a traditional inboard motor since it is not connected to the motor via a standard propeller shaft. Instead, inside a saildrive casing there is normally an L-gear that consists of a vertical (pinion) shaft, a horizontal (propeller) sha...

AI Technical Summary

Benefits of technology

[0014]In use, the first and second mating parts may be configured to apply a force to compress the gasket when the first and second mating parts are connected. The force may be applied generally vertically through a portion of the gasket received in the recess. Thus, the force to compress the gasket may be transmitted through the innermost side of the gasket causing the gasket to expand radially outwardly into the groove to seal against the collar.

[0015]The applicants have found that the shape of the groove in the collar and the shape of the recess formed by the first and second mating parts can influence the power transfer and vibration dampening properties of the mount. Accordingly, the shapes of the groove and recess should be careful chosen to provide the desired properties.

[0016]The groove and the recess may have similar or different cross-sections.

[0017]The groove and / or the recess may be generally V-shaped or C-shaped. Thus, the groove and / or the recess may be formed by two inclined annular surfaces having an angle of less than 180 degrees there-between. The angle may be between 180 degrees and 90 degrees but is preferably 90 degrees or less. The inclined surfaces may join via a curved interface or a straight (e.g. vertical) interface. In certain embodiments, the groove and / or recess may be part-circular, for example, hemispherical.

[0018]The gasket may comprise rubber and may be in form of an O-ring. As above, the type of rubber employed in the gasket may influence the power transfer and vibration dampening properties of the mount.

[0019]The gasket may be substantially toroidal forming a circle in plan view. Alternatively, the gasket may be substantially oval, obround or elongated in plan view. The use of an oval, obround or elongated gasket may be particularly advantageous since it has been found that approximately 80% of the forces applied to the gasket in use are likely to be in the forwards and backwards directions and these can be most effectively managed by having a gasket elongated in the forwards and backwards directions.

Problems solved by technology

Such a rigid mounting is fairly easy to achieve, however, a disadvantage is that a rigid mounting will transfer any vibrations caused by the propeller directly to the structures of the boat.

This may result in noise, vibrations and, in the worst case, damage to some structures.

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