Excerpted from an earlier discussion
Here ➥
http://www.cruisersforum.com/forums/...size-1577.html
Westerbeke Corporation suggests 2 hp for every 1,000 lb of
displacement for coastal cruising, and 2.5 hp per 1,000 lb of displacement for
offshore.
In their book "The Gougeon Brothers on Boat Construction" the authors suggest a good rule-of-thumb is 1 hp for every 500 lb of displacement.
Some people suggest 1 hp for every ft. of boat waterline length.
Some people suggest 3 - 5 hp (continuous rating) per long ton (to calculate the boat's weight in long tons divide the displacement by 2,240).