plowing 12.5 ft

imported_omcman

Recruit
Joined
Oct 23, 2006
Messages
2
why does my 12.5 harbercraft plow and lose steerage at 3/4 throttle and above with a15hp johnson the boat is rated for a 15 hp i have trimmed full range raised and lowered the mount of the motor to no avail
 

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,392
Re: plowing 12.5 ft

Are you over propped ? how are the RPM's at WOT ? what load do you have aboard and how is the weight distributed ? is the prop cavitating ?
The more info you can give the better the experts here can help you.
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: plowing 12.5 ft

Where is the motors cavitation plate in relation to the bottom of the hull? Should be even or slightly above the bottom. You may be running a long shaft motor on a hull designed for a short shaft ........

SHAFTEXMP.jpg
 

Scaaty

Vice Admiral
Joined
May 31, 2004
Messages
5,180
Re: plowing 12.5 ft

This needs to be moved to Boat Topics...get a better response
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: plowing 12.5 ft

From your discription I would say you have a hook in the bottom of the boat.put a 3 or 4 foot straight edge along the bottom of the boat near the transom.You are looking for a concave section.Hopefully it is not concave but straight.Let us know what you find.
 
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