proping my toon

[mrdude]

i have a tracker 24ft pontoon with a 60hp evinrude.. getting ready to put a 1985 115hp merc on it... the 115 has a 22pitch stainless prop.. and the motor has had some porting work done and am told its pushing more like 150hp.. im pretty sure the 22pitch would be over pitched for the pontoon but im thinking of cutting the prop down a bit in hopes of avoiding buying a new prop.. anybody ever done this? advice on this would be appreciated unless someone has a problem with me cutting a perfectly good stainless prop that i have no money in.

im cheap... what can i say

 

[5150abf]

Re: proping my toon

I have actually done such a thing, buddy gave me a prop that was way to big and I cut 1 1/4 off the blades, totally lucked out and it ran 5500 rpm on my 50.

So the answer is, yes you can but you probably shouldn't, this is one of those areas that you can spend way more than you save, if you get the balance off and bend your prop shaft or blow the seal and water gets in and you smoke the gear set you will wish you spent some time on Ebay looking for a cheap prop.

You havent even run the boat yet to know what that prop will do on the motor, I would start there and then see which way you need to go, no sense wrecking a perfectly good prop when it may be fine.

 

[Silvertip]

Re: proping my toon

The blade shape has everything to do with how a prop performs so simply cutting it down will affect its slip number significantly which is not what you want to happen, especially on a pontoon that requires lots of grunt to begin with. Sell the prop you have (after base-line testing) and then buy whatever you need from E-bay or Craigs List.

 

[mrdude]

Re: proping my toon

thanks guys
guess i should run it with this prop 1st... the guy i got the boat from says it was running 6000rpm wot on an 18ft boat.. so maybe i wont change anything after reading posts about how a higher pitch will increase fuel mileage... wouldnt want too lug it much but i'm figuring 5000rpm wouldnt be too awefully bad.. but if need be i do have a plasma torch and will keep the hub cool while cutting

 

[rrhodes]

Re: proping my toon

I am betting if you are pushing 150hp you will be going with a 17p, If you are running a 115hp you will end up with a 13p.

Of course your own testing is needed but those are the numbers for most 24' toons I have seen.

 

[jafo9]

Re: proping my toon

can the tracker take a 150?

 

[mrdude]

Re: proping my toon

yea.. i'm gunna try the 22 pitch.. but i was thinking a 17 pitch would be about right. if i can get 5k wot i'll stay with the 22pitch for fuel economy
i'll post results when i get it in water... right now the 115 is hanging from a tree limb and the 60hp evinrude is still on the pontoon. gunna do the swap tomorrow. my only concerns now are how i'm gunna get my cables from the evinrude to work on the merc.. i'll figure it out thou

 

[rrhodes]

Re: proping my toon

With the 115 you will get no where close to 5k rpm with a 22 pitch.

I pushed 5200 rpm with a 15p and depending on load the 13p gets me 5900 with just me and 5700 with 4 adults 2 teens and 2 little kids on board. I actually burned more fuel with the 15p because I had to run with more throttle to maintain speed. The lower pitch increased my top speed.

 

[mrdude]

Re: proping my toon

well if you say so but..... i may be close to 5k wot with 22pitch.. the motor as i said is in fact pushing 150hp came off a 18ft checkmate ski boat with 4 adults in the boat it would run 70+ mph 6000rpm.. i know the pontoon is much heavyer but its no more than 900lbs heavyer.. so i think i'll be in the 4500- 5000 ballpark but we'll see .. taking it out tuesday.

 

[mrdude]

Re: proping my toon

ok... im running at 4200rpm wot with the 22 pitch stainless turbo prop with just 2 persons on board running 27mph.. so i'm thinking a 17 would be right... waddaya think?
and i'll tell ya something else.. this 115 must be much heavier than the 60 evinrude cuz the water line on the back of the logs are about 3/4 or more up ... after pulling it out of the water checked front to back and the logs have no water whatsoever in them so i guess its ok.. dunno.. my 1st pontoon boat.

 

[rrhodes]

Re: proping my toon

In theory the 17 will put you at 5200 rpm. I am still thinking a 15p would be about right. I am getting between 5700 and 5900 depending on load with a 13p on a stock 115

 

[lmuss53]

Re: proping my toon

The Turning Point prop selector says a 19 for water sports and heavy loads with 4 people and 100 pounds of beer. I think I'd still go with a 17 though, basing that on what you saw with the 22. Is the 27 mph by GPS or tube speedo?

http://www.turningpointpropellers.com/

Time to start looking for another log for down the middle, that'll get it back up out of the water. .

Check your PM's I'm wondering what you're gonna do with the 60.

 

[mrdude]

Re: proping my toon

isnt 5900rpm a bit too high for a 2 stroke. especially a 4 stroke in your case?

 

[mrdude]

Re: proping my toon

handheld gps... teetered at 26 /27mph

 

[mrdude]

Re: proping my toon

the 91 mod 60hp evinrude w/power trim is for sale... like new cond runs perfectly $1500 ... fair price aint it?

not trying to sell it on this forum

 

[Rancherlee]

Re: proping my toon

I would try the 17 pitch personally, I think a 15 pitch might put you past 6000rpm with a light load.

22/17 is ~1.3 difference in pitch . 4200rpm X 1.3 gives ya 5460rpm plus you will be making more HP at that rpm and you will pick up more rpm because of it.

 

[TooManyQuestions]

Re: proping my toon

Okay,

Ive read this thread, and Im all confused now.

(laugh)

As some of you might have read in other posts, Im launching a 22ft new Manitou next week with a 115 Evinrude.

Im on a small 65 acre lake and will use it to fish and tube. So both slow and fast (those are technical terms/laugh).

What RPMs should I be running at. I dont know what type of prop Im getting (is that a question I shouldve asked?)

Does the trim have anything to do with the RPMs?

Dont want to learn by screwing up a $8,500 motor.

By the way, anyone else see the deal of 5 yr warranty and 500 cash back? Ask the dealer and he said he would get back to me. How do the promotions work?