Pontoon Boat & Deck Boat Forum

I bought a new Turning Point prop a month ago and it was a 13 3/4 x15. Wot rpm at that time 5400 which was in my range (5000-5500) Now I am at 4900-5000. I haven't hit anything. So why could this be happening?? Also This is driving along with the same load or even pulling a tube. I am lost.

Only two things I can think of, your either loosing compression, or a blade is bent. Even the SLIGHTEST bend can possibly make a difference sometimes.

I didn't see any bends today when I checked. And it is getting worst everytime I go out. This could cost me some $$$.

CaptainBob wrote:I bought a new Turning Point prop a month ago and it was a 13 3/4 x15. Wot rpm at that time 5400 which was in my range (5000-5500) Now I am at 4900-5000. I haven't hit anything. So why could this be happening?? Also This is driving along with the same load or even pulling a tube. I am lost.

I kind of noticed somthing along the same lines today. New prop on my boat at the beginning of the season... was turning 6000 to 6100 rpms. Today I noticed that at wot I was maxing out at 5800 rpm's. Now there were 4 people on the boat instead of just two... could that make a difference, how about the lake being alittle more choppy than the time before? I'm fine with it turning 5800 since yamaha recommends 6000 max for my motor, just curious as to what could reduce me 200 rpm's or so within a month....

Heavier loads will drop your rpm. As far as dropping 500 RPM, I would do a compression test on your motor. Something is not right and I doubt it is the prop.

One other thing can dirty toons affect it since I wet slip??

Check the tach and make sure something has not happened to it.

CaptainBob wrote:One other thing can dirty toons affect it since I wet slip??

If you have things growing under the waterline on your toons it will definitely affect your rpm and speed. The same goes for V hull boats.

margaritaman wrote:

CaptainBob wrote:One other thing can dirty toons affect it since I wet slip??

If you have things growing under the waterline on your toons it will definitely affect your rpm and speed. The same goes for V hull boats.

What can I do to the toons to keep stuff from growing on them?

You wouldn't notice this change in one outing. If you leave the dock with dirty toons you should see the same performance issues then.

as far as keeping them clean, pressure wash them regularly and you should be fine unless they already have allot of build up.

Besides dirty pontoons which will cut into your performance there are a few other things that can cause a loss of performance. On my boat the switch from ethanol free fuel to ethanol cost me 200 rpm's off the top. Another thing it done was effectively clean the fuel system displacing it to the fuel filters which then also needed purged and replaced. Your boat is getting enough age to it maybe go over the basics first which wouldn't really heart to do anyway.

First pull all the spark-plugs and inspect them for firing, carboned up, excessive gap, etc. and replace or re-gap as necessary.

Take a look at and or replace all the fuel filters.

Also check the fuel lines and verify they are both unobstructed and in sound condition. Due to ethanol some fuel lines are failing and separating in the cores and effectively blocking fuel flow to the motor.

Once you've verified and checked for function all the basically maintenance items it may then be the time to "dig deeper into your problem".