The motor sailer we voyaged over 41,000 miles on, displaced slightly over 60,000 lbs and had a 85 hp diesel. We usually ran it at about 60% of rated systained power, and rarely went over 80%. The only time you might want more power than the 135 hp, would be bucking into heavy winds and head seas--and when you get into that type of situation, there is a possibility of doing damage to the boat, so that you really may either may not to do that, or take another course. Bob Austin