My boat isn't fast enough

[jswartzel]

I have a 2001 Procraft 175 with a 125 Mercury engine. My top end speed is only 37 MPH. I have a 13.25 X17 aluminum prop. I have been told similar boats will do between 50 and 60 MPH. Any ideas? The engine runs stong and all four cylinders have 135 PSI compression.

 

[180shabah]

Re: My boat isn't fast enough

Probably need to post in the prop forum and include your WOT numbers, RPM and speed(GPS)

Still have a couple ?s though.

Are you trimming properly?
Do you have a 'foil?
do you have trim tabs / are they retracted?

 

[kenmyfam]

Re: My boat isn't fast enough

I have a 2001 Procraft 175 with a 125 Mercury engine. My top end speed is only 37 MPH. I have a 13.25 X17 aluminum prop. I have been told similar boats will do between 50 and 60 MPH. Any ideas? The engine runs stong and all four cylinders have 135 PSI compression.

Lot of possibilities that could lead to improvement in performance and many factors to take into consideration.
Motor health
Motor height and trim
Arranging the weight distribution of your people and gear
Hundreds of pounds of water soaked flotation foam in the hull
Wide open throttle RPM
Calculate the prop slip
I don't know your particular boat. Do you know of other similar outfits that perform like you say or is it hearsay ???
Post some more info and the guru's will go from there.
Welcome to iboats

 

[koko1]

Re: My boat isn't fast enough

I think 50-60 MPH with only a 125 HP motor is not accurate....Never drove a pro craft just does not sound right to me... I would think in the low to mid 40's maybe high 40's on glass would be tops for it... But I could very well be wrong...GL

 

[kenmyfam]

Re: My boat isn't fast enough

I think 50-60 MPH with only a 125 HP motor is not accurate....Never drove a pro craft just does not sound right to me... I would think in the low to mid 40's maybe high 40's on glass would be tops for it... But I could very well be wrong...GL

I was thinking the expected speed was a little optimistic as you can see from my initial post.

 

[jswartzel]

Re: My boat isn't fast enough

The reccomended RPM is 5250.My gauge reads anywhere between 5600 and 6000. Not sure how accurate it is. I do trim properly, if I went any higher the motor would be out of the water. I do not have a foil or trim tabs.

 

[180shabah]

Re: My boat isn't fast enough

The reccomended RPM is 5250

Your WOT spec is a range, not a single RPM.

gauge reads anywhere between 5600 and 6000. Not sure how accurate it is.

a 400 rpm swing at WOT - very suspect, need to verify with a shop tach.

 

[Silvertip]

Re: My boat isn't fast enough

Your speed is down because the engine is over reving due to an incorrect prop. Even a 75/90 HP engine can easily spin a 13-1/4 x 19P.

 

[bnicov]

Re: My boat isn't fast enough

Try a 21pitch prop or even 23pitch. You are over revving and have the wrong prop on your motor. How is your hole shot, does the boat jump onto plane??

 

[countvlad]

Re: My boat isn't fast enough

Try a 21pitch prop or even 23pitch. You are over revving and have the wrong prop on your motor. How is your hole shot, does the boat jump onto plane??

21,23 is a overkill for that motor and boat.... work with what you have then go from there.... get the tach working correctly so we know your WOT rpms and speed(with a GPS)