I have a 24'' 1964 Grand Banks Sailboat. An old HEAVY "wood" beauty. Against many folks suggestions (4 to 6 max), I put an 8HP on her. Turns out, I''m glad I did. Yes, it is heavy to yank up the motor mount while out on a rough sea but that extra power has been a plus. I can only turn it up to 2/3 power and even at a tad above half speed it pulls the mount and motor way down into the water. I just have to move all the weight forward. Even still, the extra strength has been worth while since she''s so heavy.
An Ericson will be considerably lighter though. 10HP may be just too much. Don''t expect to successfully wrestle with it if it dies at sea. It will be VERY heavy when it''s wavey. You''ll never kick the throttle past 2/3 the way either. If the motor is free or cheap, use it. If you are buying it new, I suggest a couple horses less.
I disagree completely with Blackhole. The weight difference between, say, a 7.5hp and a 10hp engine is negligible. The outboard-powered sailboats that I have owned all have a plate that states the max. horsepower for the hull. I would get the largest engine you can with a long shaft.
You''re welcome to disagree... I think (actually I know) you''ll be agreeing with me after you have a bad day in a rough sea where you have to unmount the motor to fix it. 7.5, 8 or 10 HP engines are heavy when it''s rough and you find yourself in a jam. Live and learn... good luck!
I asume the boat has a Westerbeke 10 in it. It''s underpowered. I have a Ericson 26 with a 7.5 YANMAR in it and it ok in calm water but can''t push tru heavy seas. Later model 26''s had a 10 HP in them. I think a YANMAR 2 GM with 14-16 HP is the way to go for these boats. Some 28''s had Universal 11''s in them , stillthis is not enough in bad conditions.