RE: Outta my league here ....
T.'Bob,
It depends on how large your sail is, and how long the 'arm' on the servo is. If either is very large/long, then a 1/4 scale hi-torque servo probably won't do the job. I wish there were a way to 'convert' smaller servos to a 'sail winch', but I sort of doubt that there is. It's an odd thing when the servo costs more than the boat, but that's the way it goes (LOL).
I'm using a 1/4 scale servo as a sail winch on a boat, but the boat isn't a large one. It works okay in all but a high wind. Not as good as a real live sail winch, but also not as costly, and I can live with it...
- LtDoc