Propellor thrust - transmission to hull

[geem]

Pretty well all of the smaller yacht engines transmit their thrust onto the gearbox and thus through to the mountings. This has never been a problem unless you have allowed diesel to leak over you mounts for years. (in which case you may get a horrible surprise in bad weather!)

I had a Victory 40 with a 75HP Perkins mounted on 4 level mounts. Behind that was a lorry propshaft with UV joints at each end. The propellor shaft itself ended (inboard) with a taper machined 6 inches from the end and a taper trust bearing attached to a substantial frame on the hull. The lorry propshaft was connected to a flange on the end of the propellor shaft. This meant that the engine - although sort of aligned, had a large tolerance to misalignment.

A little over engineered perhaps? Wonderful to have all that power on tap on a slow turning 3 blader. go any where vessel that was and fast once the wing had piped up.

We have a similar set up on a Trintella 44. The 2" s/s prop shaft terminates at the inboard end in a grooved slot that fits a tapered bush inside a thrust block. Lorry prop shaft makes the connection to the gearbox. A great design

 

[Chris_Robb]

We have a similar set up on a Trintella 44. The 2" s/s prop shaft terminates at the inboard end in a grooved slot that fits a tapered bush inside a thrust block. Lorry prop shaft makes the connection to the gearbox. A great design

They dont make boats like that any more!

 

[Bilgediver]

Well I'm happy to stand corrected, but from an engineering perspective taking the prop thrust on the engine sounds daft to me... the effect of it will presumably lead to vibration in use, and more rapid deterioration of engine mounts and crankshaft bearings.

No thrust on the crankshaft thrust bearings. They only take care of end float loads generated in the engine. The shaft thrust is taken by the output shaft bearing on the gearbox which is designed for this purposes and in some installations is also water cooled.