Low Performance

[dieselseeker]

I have a 1995 251 Proline with a bracket, 29 inch set back with a 2006 250 hp etec running a 14X19 Enertia prop. The brouchure is saying 39 to 41 mph with a 225 Merc swinging a 14x19 prop. I can only get up to 36 mph trimmed up half on the gauge before the prop starts cavitating. I have lowered the motor all the way down and raised it all the way to the top holes with no change in mph or trim angle (before prop cavitates) The hull has antifouling paint that is a little rough. Could the antifouling paint be killing my top end. The Enertia gets the boat out of the hole without slipping and trimmed up (half ways up gauge) attains 5500 rpm and jumps around, up to 6000 rpm. Would a 4 blade help or a bigger diameter prop work better for more bite and perhaps higher trim. Any one else running this Proline and what kind of speed are you getting out of it. Thanks for you input guys.

 

[dieselseeker]

Re: Low Performance

That speed was gps. What 4 blades are designed for max bow lift to reduce drag.

 

[steelespike]

Re: Low Performance

The 251 is 4,200 lbs I think you should be running a 17" pitch.
Generally a 4 blade is to improve low end performance.The rough bottom paint sure doesn't help any. In the many many 250 Etec tests they generally run 17" pitch SS on the 25ft range boats.All are running over 40 mph.

 

[Tail_Gunner]

Re: Low Performance

I have a 1995 251 Proline with a bracket, 29 inch set back with a 2006 250 hp etec running a 14X19 Enertia prop. The brouchure is saying 39 to 41 mph with a 225 Merc swinging a 14x19 prop. I can only get up to 36 mph trimmed up half on the gauge before the prop starts cavitating. I have lowered the motor all the way down and raised it all the way to the top holes with no change in mph or trim angle (before prop cavitates) The hull has antifouling paint that is a little rough. Could the antifouling paint be killing my top end. The Enertia gets the boat out of the hole without slipping and trimmed up (half ways up gauge) attains 5500 rpm and jumps around, up to 6000 rpm. Would a 4 blade help or a bigger diameter prop work better for more bite and perhaps higher trim. Any one else running this Proline and what kind of speed are you getting out of it. Thanks for you input guys.

So your saying you have a good hook up until 5500 and then she breaks lose????? Or can you run her up to wot then trim her out until she busts loose and then she starts cavitating..aka what is your wot and speed just below the point of cavitation.. (when you start to trim her out)

 

[dieselseeker]

Re: Low Performance

It will run about 5100 with negative trim and 5500 with positive trim halfway up the gauge,any more trim and it breaks loose to 6000. The cavitation plate is 4.5 inchs up from the bottom of v on the highest bolt setting. No spray off the motor. I tried a 17 pitch ss prop and it reved to 6000 trimmed half ways and would then break loose and rev higher. According to the prop slip calc. the 19 pitch prop has 33% slippage. Not very good. Would a bigger diameter prop 15.25 x 19 give me more bite and less slipage and possibly allow me to trim it up more.

 

[steelespike]

Re: Low Performance

Are you using the same brand 17" prop?
Sometimes a prop is just not compatable with a motor.
While its not good to jump around brands you may need to try something different.The Etec tests on a 24ft proline walk. 3,700lbs, used a BRP viper
17" prop 5,800 rpm at I think 47 mph.

 

[dieselseeker]

Re: Low Performance

I boat on Lake Superior and am thinking all the tests are done in salt water which would be denser and probally 2 to 3 mph faster and the rough bottom coat are the result of the 36 to 37 mph top end. I will clean the bottom next year and hope to gain 2 mph and live with that. Make sense?

 

[Randybeall]

Re: Low Performance

Something does not sound right here. You say you have anti vent plate about 4.5 inches above the bottom of the v of the hull. That seems too high, but you also say that you have moved the engine up and down as far as it would go with no change in blow out at trim up. Sounds like you have the engine to high and need some trim tabs to get more hull out of the water. The information as stated defies logic.

 

[steelespike]

Re: Low Performance

Something does not sound right here. You say you have anti vent plate about 4.5 inches above the bottom of the v of the hull. That seems too high, but you also say that you have moved the engine up and down as far as it would go with no change in blow out at trim up. Sounds like you have the engine to high and need some trim tabs to get more hull out of the water. The information as stated defies logic.

Don't forget the motor is on a bracket with 29" setback though it does seem there would be more of a difference with the height changes.

 

[dieselseeker]

Re: Low Performance

Yes i had the motor all the way down and no change in trim blow out (half way up gauge) There was lots of spray from motor (lowest setting) so i put it back up to the highest setting. (lowest bolt holes) It should be going quicker then 36 to 37 mph. This is baffling me with the no change in performance. It should take more trim with it in the lowest setting but no change so back to the top it went. It stays on plane at around 3700 to 3800 a little high I thought with full neg. trim. I have some lenco trim tabs coming. With a little tab do you think that it will help with getting the stern out of the water and the motor trim for keeping the bow up. The water is breaking behind the drivers seat leaving about 7 ft of boat in the water. (from side of boat) The 17 pitch prop is a older vintage omc and the 19 is a merc Enertia (recommended for offshore boats) I was running the enertia on my 21 ft Hydra Sport with a 200 opti. Maybe I will try a viper or a 4 blade cyclone to grab more water and see if it will let increase my increase my trim. Thanks for the help. If there is something that wakes it up and improves the performance(pardon the pun) I will let you guys know

 

[Tail_Gunner]

Re: Low Performance

Don't forget the motor is on a bracket with 29" setback though it does seem there would be more of a difference with the height changes.

Id be willing to bet his hull is slowing him down a lot. Even with his set back he's having a hell of time getting that thing to piviot. But he's probably right on a good 4 blade ss with a lot of stern lift...it would have more force or maybe success in getting the bow to air out some...

Clean your hull up with a quick sand job...25'..... She would be far more responsive...A Stilletto bay pro 11 in a 18 pitch would or could be a good choice...i have a 19' 3500 lb I/O boat loaded and can pop a 6-7 rooster tail using trim...the prop has a lot of lift and bite. But if that prop could get that hull up id bet she top out quickly...less wetted surface...bad surface at that now gone...smooth running with a clean surface you might be able run up to a 20..