Df115 Prop for Trophy

[mjbll]

I have a 1997 Bayliner Trophy 19ft center console.It presently has a 120hp Force with a SS 19p 3 blade prop.It turns 5000rpm max which is what this motor calls for and 35mph max.I`m buying a 115hp Suzuki 115 4stroke which has a max rpm of 6000rpm.The boat hull weighs about 2300lbs,the Suzuki gear case is a low 2.59:1 ratio.I actually expect this motor to outperform the Force because if I`m not mistaken the Force`s rated HP is at the crank.I run mostly offshore usually in 1-2ft seas and I`m mostly concerned about low speed planing with a full load of 4 men,etc.I plan on purchasing a aluminum "test"prop to be used as a spare before buying a SS one.Which size prop will get me into the ballpark range?

 

[walleyehed]

Re: Df115 Prop for Trophy

Just a guess here, but I don't think a 19P will be far off.
what year is the Force?

 

[mjbll]

Re: Df115 Prop for Trophy

The Force is a 97 model.The dealer is telling me a 18p but I`m thinking the max rpms would be too low?Is the gearcase ratio why I would use the around the same pitch?

 

[walleyehed]

Re: Df115 Prop for Trophy

#1 the Force is prop-rated as well.
#2, yes, the gear ratio on the DF115 will cause some misguided thoughts.
That DF115 is a strong engine when run at 5800-6000.
Your dealer may not be far off...I may be wrong thinking 19, but I have a DF115 on a 24ft pontoon and a 17P put it at 5200..we tried a 15P and it hit the rev-limiter. I had the prop worked a tad and it came out at 6000 even.
Try the 18...

 

[mjbll]

Re: Df115 Prop for Trophy

Thanks.By the way,whats the top speed on that pontoon boat?

 

[walleyehed]

Re: Df115 Prop for Trophy

If i remember correctly, with 3 of us on board, we were pushing 28mph GPS at 6k.

 

[mjbll]

Re: Df115 Prop for Trophy

Ok well it should go at least as fast as the Force on my boat.Has it been a reliable motor so far?

 

[walleyehed]

Re: Df115 Prop for Trophy

Let's put it this way....If I "Had" to put a 4-stroke on my boat, there would be no option other than the suzuki.
This 115 has been Flawless....
I burn more fuel in 1 day in my 200 2S, than he burns in a month...we both have houses on the same lake and both of us spend about the same amount of time "fishing", although I have a bad habit of bending the throttle lever clear over trying to get another 1 mph...'nother story....
The DF115 is one, if not the most powerfull 4S 115 I've been around...It will run off and leave alot of 115 2S engines.