Prop question for my pontoon

[capnunu]

I have a 2011 Bentley Cruise SE 220, with a 2011 Mercury 4 stroke 90 hp EFI Boat and motor weigh 2100 LBS 1000 LBS for people and gear and a 36 gallon tank.

The number on the prop is 48 854352A45 14P

I was out again yesterday and I think I have the wrong prop. When I bring up the RPM's past 5500 the rev limiter kicks in where the motor starts to rev up and down. but I still have about 1/4 way to push the throttle. On the GPS I and doing 21 mph at 5500 RPM.

Should I not be able to push the throttle right to the end and not go over 5500 rpm? I just bought this boat from a lady and the motor only has 27 hours on it. Is it possible there is a program on the motor for a break in period and it needs to be reprogrammed?

Sorry for all the questions. I do all my own repairs on all my vehicles, quad and sled but am new to boating and it just doesn't feel right.

Thanks for your help.

 

[SkiDad]

Re: Prop question for my pontoon

i would think something else is wrong - you should be at high 20's mph at that rpm and engine. Are you trimming up the engine after take off ? Does the engine sit low enough in the water

if so I would try a larger pitch prop of similar diameter - say 16 or so

 

[MH Hawker]

Re: Prop question for my pontoon

Pontoons are a different breed of boat and what apply s to most dosnt not on a toon. that being said I would think your over propped and that is why the limiter is kicking in. With out knowing more than its a 14 p and the rev limiter is kicking in at 5500 and with 1/4 to go I would guess a 11 P. A 7,9,11 and a 13 Pitch is common to pontoons.

A 16 p would not be any where close and make it worse.

 

[capnunu]

Re: Prop question for my pontoon

As for the question about the trim. I am not sure if the motor in deep enough in the water. I couldn't find a manual adjustment for the trim and when I am running if I trim up the motor with the hydraulic trim I don't get very far before the motor seems to be coming out of the water as the revs climb up.

The motor was installed by the marina where I dock the boat so I am assuming it was installed correctly.

 

[steelespike]

Re: Prop question for my pontoon

Power trim on a pontoon is usually more for getting the trim set for the least ventilation than to accomplish much in the line of speed.
Your motor is rated for 5000-6000 rpm. So I think the rev limit should cut in about 6000.
Perhaps they lower it on a new motor.

 

[kenmyfam]

Re: Prop question for my pontoon

Pontoons are a different breed of boat and what apply s to most dosnt not on a toon. that being said I would think your over propped and that is why the limiter is kicking in. With out knowing more than its a 14 p and the rev limiter is kicking in at 5500 and with 1/4 to go I would guess a 11 P. A 7,9,11 and a 13 Pitch is common to pontoons.

A 16 p would not be any where close and make it worse.

Would a lesser pitch not increase the max RPM and kick the rpm limiter in at slower speeds ???
We really need to know what the rpm limiter is meant to be set at for this motor. If it is 5,500 rpm then
Increasing pitch with the reported facts so far may be the answer in my opinion. See if you can get a loaner prop or 2 to try out and experiment.
Anyone have one of these motors and know the max recommended rpm ??
Just my thoughts.

 

[MH Hawker]

Re: Prop question for my pontoon

Your right kenmy a higher pitch will drop the rpms.

 

[capnunu]

Re: Prop question for my pontoon

Mercury reports that full throttle RPM is from 5000 to 6000.

 

[drewactual]

Re: Prop question for my pontoon

Better to rev higher than lower at wot... Lugging hurts engines more, but neither is good.. aim for 5700-6000rpm.. you'll wanna comfortably hit that max rpm.