Any Prop experts out there?

[pilldok]

I have a 2000 model Bennington Tri Toon 25ft powered by a 2001 Mercury 150 Optimax. Dealer closed immediately after purchase and left me with an incorrect prop. They mounted a 19 pitch Revolution 4 SS prop on the boat and WOT is way too low. What should I use? Should I obtain WOT figure when engine is trimmed up to optimal position or when trimmed all the way down?

 

[JB]

Re: Any Prop experts out there?

Tell us your WOT rpm with optimum trim, Doc. Then we can estimate what to start with in "propping her out".<br /><br />Good luck.

 

[pilldok]

Re: Any Prop experts out there?

Originally posted by JB:<br /> Tell us your WOT rpm with optimum trim, Doc. Then we can estimate what to start with in "propping her out".<br /><br />Good luck.

 

[pilldok]

Re: Any Prop experts out there?

The following are the WOT results from the current prop as well as two additional props I tried to no avail. These figures were all produced with the motor trimmed all the way down.<br /><br />19 pitch 4 blade SS---------4040 rpm<br />17 pitch 3 blade alum-------4440 rpm<br />15 pitch 3 blade alum-------4950 rpm<br /><br />I have been told that WOT should be between 5250 to 5750 rpm!I would appreciate your help for I have no local support and mercury is hard to communicate with. Boat is a 25ft TRI toon with a hull weight of 2620. THANKS!

 

[pilldok]

Re: Any Prop experts out there?

JB, sorry but all these figures were taken with trim down. Boat is in the water 20 miles away so i will have to go check again and get back with you probally after this weekend.

 

[LubeDude]

Re: Any Prop experts out there?

Looks like you will need to go all the way to an 14.25 or 15" X 11P in a Stainless. I dont think trimming will do too much with a toon. <br />

<br /><br />

 

[gss036]

Re: Any Prop experts out there?

Too bad you are so far away, I've got a spare 15 1/4 X 15 cupped Michigan wheel you cloud try. I used it on my 200 Merc for a fast hole shot for skiing.

 

[rickdb1boat]

Re: Any Prop experts out there?

You should be able to swing the 15" prop with no problem. Trim it out and see what she runs... Also, give us the top speed at trimmed out running..

 

[pilldok]

Re: Any Prop experts out there?

Originally posted by LubeDude:<br /> Looks like you will need to go all the way to an 14.25 or 15" X 11P in a Stainless. I dont think trimming will do too much with a toon. <br />

<br /><br />

 

[pilldok]

Re: Any Prop experts out there?

Thanks Lube Dude! Since we bought this boat with no trailer and my original dealer has closed I am having a hard time getting this problem resolved. All suggestions are appreciated.

 

[pilldok]

Re: Any Prop experts out there?

Originally posted by rickdb1boat:<br /> You should be able to swing the 15" prop with no problem. Trim it out and see what she runs... Also, give us the top speed at trimmed out running..

 

[pilldok]

Re: Any Prop experts out there?

Top speed is another issue by the way. Boat will only run 20-25mph at wot. I know it is only a tri-toon but i expected much more paired with a 150hp optimax. Thanks for your help. I will try to get rpm at wot trimmed at max without loss of "bite" this weekend.

 

[Mercathode]

Re: Any Prop experts out there?

Hi Pill<br />How does this toon respond to trim. Does your RPM increase any at all when trimmed up. If it does I would use that to measure. I think your performance should be better than your getting.<br />LW

 

[pilldok]

Re: Any Prop experts out there?

954 Winns,<br /><br /> Trim does of course increase my rpms and it actually does a pretty good job of lifting the bow of the boat. Desired WOT rpm can not be acquired however before prop looses "bite". I have yet to make it back to the lake so I can't give you an accurate rpm reading when trim positioned optimally. Is this the correct method of determining WOT (with trim up)?<br />PILL DOC

 

[BillP]

Re: Any Prop experts out there?

Contact Bennington or Merc, they should be able to give you expert advice on this exact rig. Also, Merc had a prop exchange program at one time but I don't know if they still do. They let Merc engine buyers borrow different props to dial the rig in before purchasing the prop. It may not hurt to ask them about it. Typical application for pontoon boats is a large diameter with low pitch. I personally wouldn't go smaller with the diameter unless you can't dial it in otherwise.<br /><br />My 20' toon only changes about 50 rpm between full down and up trim. It sees little to no top rpm drop with 2 people or 10 people aboard. Only the speed changes.

 

[pilldok]

Re: Any Prop experts out there?

Thanks BillP