24' with a 115 Evinrude gets only 15 mph.

[fun_friend]

I have recently purchased a 24' Princecraft with a 20" - 115 Johnson. Both 2000 models. The previous owner had just added the 115. It came with a 70 and he said it would only run about 15 mph and he couldn't pull a tube. He had added a 14x13 prop. This prop ventilated badly and the boat would only run 16 mph and still had nearly half the throttle left. I added a hydrafoil and it only made it worse. I pulled the hydrafoil and put on the spare prop, a cupped 13-7/8x11. It works great with no ventilation or cavitation but the boat only runs 15 mph @ 5800 rpm. WOT is 6000 with this prop and that's the last 1/4 throttle but no increase in speed. I know if I want to go fast I should have a speed boat but the 115 should push it faster than 15 mph.

My question, what prop should I be running on this boat?

Thanks for your help.

[1roadking]

Your motor is sitting way to high

[fun_friend]

Thanks, where should it be sitting? Where should the cavitation plate be?

[tkrein]

cavitation plate should be at equal to the bottom of the pontoons or as close as you can get

[BassFrequency]

cavitation plate should be at equal to the bottom of the pontoons or as close as you can get

wait a min there, most 2 loggers i see, the skeg is about all thas below the logs. mine is that was and i have half the ponies and got 6-7 mph on ur 115. that just dont add up quite right

[fun_friend]

BassFrequency, Thanks for the reply. What prop are you running?

[crspang]

Are you using a GPS to check speed? Also on the tach is it set for a 4cyl or 3? Just wondering since the motor was switched.

[dodger]

I think the previous advise was right, make sure your cavitation plate is at least even with the bottoms of the tunes first, try it there, then maybe just one notch below, however if you go too low there will be a bit more drag at take off until you can trim up after gaining some speed.

After you feel that you have the right motor depth, then figure out if you need a prop change. Right now it sounds like you have the right prop but would like a little more speed. What were the conditions of the top speed you got now, how many people, how much gas weight, load, water conditions all this information will give us a better idea on what to recommend. Keep 70 % of the weight to the back half of the boat, 30% to the front half at least until up to speed, then people can shift a little.

Even taking the prop you have to a prop shop and having them put more cup on it may help, ss may help but $$.

Princecraft are well buildt, maybe a bit heavier than some pontoons and did I read right, you have 20" tubes? Those are small compared to what is being put on now days.

It maybe that you are sitting low in the water to start with, pushing a lot of water and what you are getting maybe about as good as you will get.

[fun_friend]

This boat has 25" tubes and a 23 gallon fuel tank. I have had four people with no other weight or eight people and 3 ice chests full of ice & food & drinks with maybe 1 mph reduction in speed. The most I got out of the 13-7/8x11 is 15 mph and the 14x13 was 16mph. The first time was on a lake and the water was calm. The second time on a river and the water was calm. I moved folks around from front to back just experimenting.

The mph is not with a GPS. I'll have to check the tach to see if it's set for a V4 or 3 cyl.

You guys are a world of knowledge.

Thank you all.

[slingshot]

I run a 14X13 aluminum on mine. tops out at 27 mph.

[GXPWeasel]

I have a 90hp with a 26" toon, and currently run a 13 1/4 x 17p prop. which is too slow. I hit max RPM ( 5600 ) at about 3/4 throttle, and going 22-24mph. on the speedo. I am switching to a 19p prop. here shortly, and hope to get 25mph. consistantly.

You should be getting close to 25 mph with your toon, as it is very similar to mine, only with 25 extra ponies.

[dodger]

I'm with slingshot on using a 13 pitch which will get you more top end, maybe even a 15 but really watch that you are not loosing too many rpms with that one. A prop shop might let you try out a couple to see which works best for you and only charge you for the one you keep. Did you check the cavitation plate height? Where did you find it to be, a little high?

We have a triple toon, we get best speed and rpms with a 19 pitch, 5800- 6000 on our 115 Yamaha, but for sports and fully loaded with family it does better with a 17 pitch, but when we leave that on when just the two of us we have to watch the rpms so they don't go too high!!!! It's on a lift for the summer so we aren't going to be changing it any to often this summer.

Keep us posted.

[trott46]

You need to get a gps speed with just you on the boat to get a true base line of were you are. Also if I read correct you have a 20 in shaft on your motor. If so the you may be to high on the motor as most pontoons require the 25 in shaft. My 22 ft tritoon with a merc 115 with a 15p prop runs 30 on the gps and i think i could go up in pitch a little but I carry a load most the time. With your toon being a two logger its not going to be a speed demon but you should be in the 20's with your set-up.

[fun_friend]

So, the general concensus is I need to lower the motor. I just bought a 5-1/2" set back jack plate. I'll install it and lower the motor. Now, if I've read the forums correctly a prop shop can cup my 14x13 aluminum prop. It's brand new. I'll post the results. Thanks all for the info.

[margaritaman]

So, the general concensus is I need to lower the motor. I just bought a 5-1/2" set back jack plate. I'll install it and lower the motor. Now, if I've read the forums correctly a prop shop can cup my 14x13 aluminum prop. It's brand new. I'll post the results. Thanks all for the info.

Before you do any adjusting check your speed with a gps. You can use a portable car gps to check your speed. The speedometer on your boat could be off as much as 5 mph so you could be doing a lot of adjustments and spend money needlesly. I have a heavier old pontoon with a 115 and loaded with 8 adults will only get about 19 mph. Half that load will take me 25 - 27 mph depending on water conditions.