Marine propulsion and constructional details thereof

Abstract

A mount for supporting part of a marine drive system to a marine hull, the mount comprising a rigid outer housing ( 832 ) defining a radially outer circumferential surface on its radially inner surface, a resilient mounting ( 831 ) disposed radially within the outer housing and defining a radially inner circumferential surface, the marine drive system passing through and supported by the resilient mounting in use, wherein a circumferential radial gap is provided either between the resilient mounting and the rigid outer housing or within the resilient mounting.

1 . A mount for supporting part of a marine drive system to a marine hull, the mount comprising:
 a rigid outer housing defining a radially outer circumferential surface on its radially inner surface;   a resilient mounting disposed radially within the outer housing and defining a radially inner circumferential surface, the marine drive system passing through and supported by the resilient mounting in use;   wherein a circumferential radial gap is provided either between the resilient mounting and the rigid outer housing or within the resilient mounting.   
     
     
         2 . A mount according to  claim 1 , wherein the rigid outer housing is substantially annular. 
     
     
         3 . A mount according to  claim 2 , wherein the rigid outer housing is circular. 
     
     
         4 . A mount according to  claim 2 , wherein the rigid outer housing has an eccentric form. 
     
     
         5 . A mount according to  claim 1 , wherein the resilient mounting is substantially annular. 
     
     
         6 . A mount according to  claim 5 , wherein the resilient mounting is circular. 
     
     
         7 . A mount according to  claim 5 , wherein the resilient mounting has an eccentric form. 
     
     
         8 . A mount according to  claim 1 , wherein upon operation of the marine drive system the marine drive system radially deflects an arcuate portion of the resilient mounting into a corresponding arcuate portion of the gap. 
     
     
         9 . A mount according to  claim 8 , wherein the gap is dimensioned such that the rate of force produced by the marine drive system to the radial deflection of the marine drive system is substantially linear. 
     
     
         10 . A mount according to  claim 9 , wherein the gap is dimensioned such that the highest solid-body resonant frequency of the marine drive system is less than times the lowest forcing frequency generated by the marine drive system. 
     
     
         11 . A mount according to  claim 1 , wherein upon operation of the marine drive system the marine drive system deflects an arcuate portion of the resilient mounting into a corresponding arcuate portion of the gap and compresses the arcuate portion of the resilient mounting against the rigid outer housing. 
     
     
         12 . A mount according to  claim 11 , wherein the gap is dimensioned and the resilient mounting is formed such that the rate of force produced by the marine drive system to the radial deflection of the marine drive system increases progressively. 
     
     
         13 . A mount according to  claim 1 , wherein the resilient mounting is formed from a micro-cellular polyurethane material. 
     
     
         14 . A mount according to  claim 1 , wherein the circumferential radial gap is an air gap and is provided over an axial length of the resilient mounting. 
     
     
         15 . A mount according to  claim 14 , wherein the remaining axial length of the resilient mounting is compressed, in use, such that it forms a seal between the outer circumferential surface and the inner circumferential surface. 
     
     
         16 . A marine craft having a hull and a transom positioned at the rear of the craft, the craft comprising a marine drive system attached to the transom by a mount comprising
 a rigid outer housing defining a radially outer circumferential surface on its radially inner surface;   a resilient mounting disposed radially within the outer housing and defining a radially inner circumferential surface, the marine drive system passing through and supported by the resilient mounting in use;   wherein a circumferential radial gap is provided either between the resilient mounting and the rigid outer housing or within the resilient mounting.   
     
     
         17 . A mount for supporting part of a marine drive system on a marine hull, the mount comprising:
 an annular resilient member having radially spaced inner and outer circumferential surfaces, wherein an annular groove forming an air gap is provided between the inner and outer circumferential surfaces.