1997 75hp Force prop question

Sipster

Recruit
Joined
Jul 5, 2005
Messages
4
I have a '97 Force 75hp on a 22' pontoon boat. It has a 15 pitch 3 blade prop on it. Max RPM I get is about 4800. I can't seem to get more than 15mph out of the boat. I know it's a pontoon boat but i'm thinking I should get a little more. It seems to me that the lower unit on the engine is very small resulting in a small prop compared to other engines of that HP. Am I just being an idiot and that's the way it is?<br />Any advice would be greatly appreciated.......
 

WillyBWright

Fleet Admiral
Joined
Dec 29, 2003
Messages
8,200
Re: 1997 75hp Force prop question

Welcome to iboats. :) <br /><br />A 15 on a pontoon? Too steep! You need a 12 or 13. That will allow the motor to reach full RPMs and full Hp. You might pick up a litte speed, but don't be too optomistic. 2 or 3mph will be about all. But you will avoid damage to the motor from lugging it. 2-strokes love RPMs. :) <br /><br />As you say, most other 75s use a larger diameter prop. I suppose it was to help keep the cost of the motor down. That, and the Force 75 is kinda weak compared to the others.
 

Sipster

Recruit
Joined
Jul 5, 2005
Messages
4
Re: 1997 75hp Force prop question

Thanks for the welcome!<br />I was thinking the same thoughts. the 15 came on the engine from the dealer. I just always see other pontoons flying ( at least a little faster than me) I guess my expectations were a bit to high. I will try a lower pitch and let everyone know how I make out.<br />Thanks for the reply....
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,657
Re: 1997 75hp Force prop question

Pontoon shape and design can have a major impact on speed.<br />A typical pontoon really starts to max out at 15-20 mph.<br /><br />Yes your motor has a small lower unit and prop. It is a "leftover" lower unit from earlier year 40-60hp motors.<br />Because of this, and other reasons, your motor (and mine) performs more like a 50hp than a 70.<br /><br />I run a 10.25 X 15p prop on my 16' aluminum v hull and get 5300 rpm. Think you will need a 12p to let the motor run right.<br />But don't expect much more top speed.
 

Sipster

Recruit
Joined
Jul 5, 2005
Messages
4
Re: 1997 75hp Force prop question

Thanks alot for the input and advice!!!<br />I'll let you know how I make out..<br /><br />THANKS!
 

Sipster

Recruit
Joined
Jul 5, 2005
Messages
4
Re: 1997 75hp Force prop question

I believe I have the same a 10.25x15 prop.<br />Looking at props available I see they go up to 10.75. Will it make much difference if I buy a prop a half an inch bigger? I was looking at a 10.75x12.<br /><br />Thanks!
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,657
Re: 1997 75hp Force prop question

A slightly larger diameter prop will not hurt, may help a little, but not much. Pitch will have a much greater effect.
 

speeddemon1452

Seaman Apprentice
Joined
Jun 19, 2005
Messages
37
Re: 1997 75hp Force prop question

I have a 20 foot hydra poontoon with a 70 hp force 1995 and it has a 10 inc prop with 13 pitch and WOT is 4200 rpm. this boat is faster then any pontoon i have seen on the water so far, don't know if its diferent then the 75 hp force motor but fig i would tell you anyways
 
Top