Motor height on pontoon boat?

Hey, I'm new to pontoon boats bought a new 21' fish & cruise suntracker with a 90 4-stroke. I've had the boat out three different weekends. I love the boat we had a great time. I have a question about the motor height. My motor came set two holes up on the transom and that seems too high from what I hear. I ordered a stainless prop from the dealer he got me a 12 degree pitch prop but I noticed the RPM at wot goes over 6000 which is too high the motor should only go 5000 to 6000 wot and the boat only topped out at 22 mph/GPS speed at 6300. I pulled it back as soon as it went over 6000 rpm. Now the first weekend after break in I had the original aluminum prop a 15 degree pitch it topped out at 6000 and ran 28 mph according to GPS which was great. The only variable is the amount of fuel in the tank the first weekend I fueled up 42 gallons so it set lower in the water. I know the lower pitch drops the speed and raises rpm by 200 rpm per degree. I'm wondering if I should drop the motor before changing anything else out on the boat. Are there any other 21' suntracker owners out there with 90 hp motors on them and how high are there motors set? Should I get the dealer to lower my motor? Any help would be appreciated.

Re: Motor height on pontoon boat?

If you're getting 28 MPH with a 15 pitch aluminum prop I don't think you need to do anything in terms of motor height. Not sure about the newer 4 strokes, but I have the same rig (2002) with a 2 stroke and 5500 RPMs is the WOT max. If your max is 6K you're in good shape. If not, you might consider increasing pitch.

Re: Motor height on pontoon boat?

There is no need to lower the motor unless ventilation is experienced. Ventilation occurs when the prop loses its bite on the water.

Re: Motor height on pontoon boat?

Funny I have a 15' duracraft also. Hey you never said how your motor is set. Well I'm going to put the original prop with the 15 degree pitch and same amount of fuel and see what happens, I'll let you know.
Thanks,

Re: Motor height on pontoon boat?

I think I'd ask the dealer to exchange the 12 which overevved the engine, for a 15. No sense buying a SS prop, then keeping it for a spare. I think you are propped good and at the right height for now.

Re: Motor height on pontoon boat?

Thanks for the advice. I'm taking the boat out with the same amount of fuel and the original 15 degree alum. prop to campare both props with the same weight and height. Then I'll go get the SS prop changed out.
Happy boating

Re: Motor height on pontoon boat?

I have a 21" Signature with a 90 ELPTO and when i got it the motor was all the way DOWN.

I noticed A LOT of splash behind the boat, and it turns out with it that low TOO MUCH motor is in the water, and the non hydrodynamic parts are causing a lot of splash, as well as some extra unneeded drag im sure.

I raised it one hole, which helped some, but it still needs to come up more.

EDIT: mind you this is with only 2 people in the boat (the norm for me), im sure the issue would be exacerbated with a heavier load.

Ill try and take a pic today, before and after.

Re: Motor height on pontoon boat?

I would put the aluminum 15" prop on and be done. That's what I have on my 20'er with the 90 Merc 4 stroke and it also does the same 28 mph. I tried a SS prop and could never get as good of results that I got from the original Black Max prop. I've found that (at least on toons) you will see no real advantage going to SS over aluminum till you get higher up in the HP ranges (150 and over).