Offset prop

[George green]

Hi I have a 45ft yawl which has a offset prop. The prop is on the port side and turns clockwise in forward. What are the benefits of this.

 

[HissyFit]

Easier to get a bent prop shaft out past the rudder, and a new one in?

 

[George green]

Is that the only reason. What affect does it have on the boat. We haven’t sailed her yet as she has been having work done for the past year.

 

[rotrax]

I imagine it never had an engine when it was first built.

Sticking an engine in 'on the piss' was a way to fit an engine with room for the correct size prop to swing.

The Trinity sailing vessel 'Golden Vanity' was the same. In fact, even more offset.

Expect handling to be interesting. It will likely turn much better one way than the other in ahead, and going astern it might well be a lottery.

 

[Jodel]

With a shaft that is angles downwards the down going side of the prop (starboard) will give more thrust than the up going side thus giving a small push to port to counteract the push to starboard from being offset in the first place. (All assuming that the shaft is parallel to the centreline).

 

[Tranona]

The usual reason for doing this was because there was not enough "meat" in the stern timbers to fit a centre line stern tube, plus getting the prop out in clearer water, again because there was not enough clearance for the prop in the aperture. a side benefit is that it makes it easier to remove the shaft without removing the rudder or lifting the engine to pull it out through the boat.

As suggested it will probably have tricky handling, particularly in reverse.

 

[George green]

With a shaft that is angles downwards the down going side of the prop (starboard) will give more thrust than the up going side thus giving a small push to port to counteract the push to starboard from being offset in the first place. (All assuming that the shaft is parallel to the centreline).

It is parallel yes