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Prop for Seahog Hunter with Yam 55

Posted: Wed Mar 25, 2009 3:23 pm
by cookie1
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

Posted: Wed Mar 25, 2009 4:02 pm
by squiresoak
Hi Cookie1, I have no experience with props but would think that you would get a better response if you posted it in the boat owners forum, there are some quite knowlageable guys in there.

Cheers

squiresoak

Posted: Wed Mar 25, 2009 4:50 pm
by rabbi2
Google ribble marine as he had a lot of S/H props for sale
Cheers keith :D

Re: Prop for Seahog Hunter with Yam 55

Posted: Wed Mar 25, 2009 6:33 pm
by tomcat
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
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.
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!

Posted: Wed Mar 25, 2009 6:58 pm
by cookie1
Thanks for the comments. Other oweners of seahog hunters are acheving top speed of 38 -40 mph running 50hp engine. I may have confused you with the boat doing 30mph at 5500 rpm.This is the engines max rpm and did not exceed it although it would of reved higher.

Allen

Posted: Mon Mar 30, 2009 4:18 pm
by cookie1
Thank to every one. Now found out the sizes I need. for ref. 10 5/8 x 19
or 10 5/8 x 17

Posted: Mon Mar 30, 2009 4:39 pm
by rabbi2
Glad you got sorted. Cheers keith :D :D