Outboard sail drive

[Forecaddie]

I am going to take a 4hp outboard and make it a through hull fixed saildrive. What would be the place for the rudder? Can I have it 2 feet aft?

 

[bajansailor]

On what type of sailboat are you going to install this through hull 'fixed' saildrive?

Are you planning on having a watertight seal around the leg, or will there just be a rubber gasket, in similar fashion to a conventional' saildrive leg?

If the former, this might be difficult to achieve; if the latter, then you might as well just have an outboard well in the hull (in the cockpit area), and have the 4 hp engine easily removable.

 

[Forecaddie]

Water tight seal. Conventional but removing the leg and shortening the drive shaft. It will be for a 24’ power tri. I think I will have short 4” skeg with rudder. The hull I am using is a pointed catamran hull. The have adjustable outriggers to bring them close to the hull then wide when I transport things or go island hopping and camping. 4hp so I don’t have to register the boat.

 

[HJS]

If you do not want to build a boat with an efficient stern, it is better to place the engine aft and provide it with a foil. In this way, you can adjust the engine position and tilt to achieve the highest efficiency.
This of course assumes that the position of the overall center of gravity is optimized.
JS

 

[Forecaddie]

Thank you. Can you explain “efficient stern”?
Rowing sculling hulls have pointed sterns. Good Idea for easy adjustability.

 

[HJS]

Comparing to a rowing scull is not relevant. A rowing scull is limited by rules. When the design is free, the hull has a wide stern as in all hulls intended for Coastal Rowing.
Hull speed https://www.boatdesign.net/threads/hull-speed.32698/page-2#post-914347
JS

 

[Forecaddie]

Thanks mate. I read the forum you mentioned and previous responses mentioned a hydrofoil on the stern of the main trimaran hull.I have looked at the Hysucat stern foils and may explore doing something like that. Thanks

 

[SolGato]

You could also consider using X2 fixed motors spaced apart and use independent forward and reverse thrust for steering which would eliminate the need for a rudder.

 

[Forecaddie]

Thank you, I will look at the manufacturer-