I have gust fitted a Yam 55 to My Seahog Hunter, it has a standard 10 5/8 x 13 prop . at 5500rpm it is doing 30mph with very fast pick up. I feel it is under proped as I am looking to cruise at about 28 mph at about 4000 -4500 rpm. Has anyone any experiece of proping this boat with 50hp engine. I think that I need a 10 5/8 x 15 of 17 or 11 1/4 x 14. Any advise would be helpful
Allen
Prop for Seahog Hunter with Yam 55
Re: Prop for Seahog Hunter with Yam 55
Standard propellor selection is made on the basis that maximum engine revs can be reached with the prop' at full throttle. ie if max revs for the engine are 5500, this should just be achievable at full throttle.cookie1 wrote:I have gust fitted a Yam 55 to My Seahog Hunter, it has a standard 10 5/8 x 13 prop . at 5500rpm it is doing 30mph with very fast pick up. I feel it is under proped as I am looking to cruise at about 28 mph at about 4000 -4500 rpm. Has anyone any experiece of proping this boat with 50hp engine. I think that I need a 10 5/8 x 15 of 17 or 11 1/4 x 14. Any advise would be helpful
Allen
As a rule of thumb a 2" coarser prop reduces revs by approx 200 revs at full throttle. Don't overload the engine with too coarse a prop' as it can be detremental to performance and fuel consumption.
If top speed is only 30, 28 is highly unlikely to be achieved as a cruising speed. 20-25 sounds far more realistic.
Try doing 2mph under the top speed of your car and see if that feels like comfortable cruising!