Fisher Pontoon motor mounted wrong?

limoman

Seaman Apprentice
Joined
Apr 3, 2012
Messages
38
I have a 2003 Fisher 220 with an outboard Mercury 115 EFU 4 stroke. My issue is when I take off I have to have the trim all the way down and once it is WOT I just tap the trim for a 1/2 second and it revs really high and the boat starts surging from the prop coming up to high. When I lean over and look at the engine it is still angled way down and no where near where the trim level should be. Even when I run the trim all the way down WOT across the lake occasionally it does it when crossing small waves. It looks to me like the engine is mounted way to high not allowing the trim to be used.

Any ideas?
 

MinUph

Chief Petty Officer
Joined
Jun 5, 2011
Messages
466
Re: Fisher Pontoon motor mounted wrong?

You should have a trim pin that you can place in a lower hole. It is what stops the downward motion. If it doesn't do the trick you will need to drop the motor down a hole on the transom. When trimmed all the down the motor should be about parallel with the water.
 

5150abf

Vice Admiral
Joined
Aug 12, 2007
Messages
5,808
Re: Fisher Pontoon motor mounted wrong?

Can you drop the motor a few inches or is it already down all the way?

If it is down all the way is it a long shaft motor, a short shaft ona pontoon doesn't work very well, measure from below the cowling to the bottom of the engine and report back.
 

limoman

Seaman Apprentice
Joined
Apr 3, 2012
Messages
38
Re: Fisher Pontoon motor mounted wrong?

Well when I look at it in motion the engine is way back pushing the water downward @ at least 25-30 degree's. It is very noticeable and not even close to where it needs to be. If I raise it level like the trim should be I can't go over 3,000 RPM's without it losing propulsion and the engine reving up to 5,800. It looks like I can drop the engine down but would have to drill new holes and it will only go down about an inch then.

I will get some measurements this week.

Thanks for the responses.
 

MinUph

Chief Petty Officer
Joined
Jun 5, 2011
Messages
466
Re: Fisher Pontoon motor mounted wrong?

It doesn't sound right for you to drill holes to move the motor down. I would take it to a marine wrench and ask them about the problem before drilling anything. Is the cavitation plate level with the water while underway?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Fisher Pontoon motor mounted wrong?

He doesn't have to drill new holes to move the motor down. You merely remove the bolts, set the motor full down on the pod and reinsert the bolts. Unless you are attempting to create a hot rod, I suggest all pontoon owners set there motors full down on the pod. If it is already mounted full down, then you perhaps need a different prop. Pontoons need props with wide, rounded blades (a work prop or pontoon specific prop).
 

MinUph

Chief Petty Officer
Joined
Jun 5, 2011
Messages
466
Re: Fisher Pontoon motor mounted wrong?

I suggest all pontoon owners set there motors full down on the pod. If it is already mounted full down, then you perhaps need a different prop. Pontoons need props with wide, rounded blades (a work prop or pontoon specific prop).

Is this always the case Silvertip? Mine is mounted one hole up. My prop guy told me to move it up another and try a new prop I had purchase here. It made matters worse so I put it back down to one from the bottom. I only 4500 at WOT and it should get 5500-6000. I'm told by Michigan prop co. there is no better prop for my Honda 40.
Sorry to hijack.
 

limoman

Seaman Apprentice
Joined
Apr 3, 2012
Messages
38
Re: Fisher Pontoon motor mounted wrong?

Is this always the case Silvertip? Mine is mounted one hole up. My prop guy told me to move it up another and try a new prop I had purchase here. It made matters worse so I put it back down to one from the bottom. I only 4500 at WOT and it should get 5500-6000. I'm told by Michigan prop co. there is no better prop for my Honda 40.
Sorry to hijack.

Hijack all you want. This is my second Pontoon and I need all the input I can get. However I would say yea on your situation because the lower it is the more trim control you have. I was told that one inch of water makes a bigger difference than folks realize.

I will be back at the lake house Thursday and will probably pull it out and bring it home to upgrade a few things and check the measurements back there.

I just put a "pontoon" specific prop on it but will double check to make sure when I get it here.

Thanks for all the input.
 

limoman

Seaman Apprentice
Joined
Apr 3, 2012
Messages
38
Re: Fisher Pontoon motor mounted wrong?

He doesn't have to drill new holes to move the motor down. You merely remove the bolts, set the motor full down on the pod and reinsert the bolts. Unless you are attempting to create a hot rod, I suggest all pontoon owners set there motors full down on the pod. If it is already mounted full down, then you perhaps need a different prop. Pontoons need props with wide, rounded blades (a work prop or pontoon specific prop).

Actually I think I do. I believe it is in the lowest setting now & to move the motor down anymore I may have to drill new mount holes. Not positive but thinking that is the case. My Fisher sits very high out of the water with large pontoons and about 6 inches between the pontoons and the body.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Fisher Pontoon motor mounted wrong?

Better look at where the ears on the transom bracket are sitting. If they are down tight against the top of the pod then your only choice is to notch the pod. I seriously doubt that is necessary. The only time that should be necessary is when the wrong engine (wrong shaft length) is mounted on a pontoon. Pontoons take a 20 inch shaft period. Your 115 is not likely a 15 inch shaft. It is also possible that the prop has too little pitch and consequently just blows out. A prop supplier cannot tell you (accurately) this is the right prop not knowing the actual peformance numbers (which you can't provide because of the blow out problem). Engines on pontoons operate in very turbulent water and need all the bite they can get. To do that they need depth (as in mounting as low as possible) and the proper workboat or pontoon prop. Work boat/pontoon props have a uniform very rounded blade shape so they work better in reverse and forward than a traditional prop for a planing hull.

As for mounting height, you can certainly fine-tune engine height on a pontoon just like you do on a planing hull. But why not set it once and forget it since you will likely end up low anyway. Tri-toons with high HP motors probably can take advantage of height-tuning. Twin-toons are not speed demons so it simply is not worth the effort. Prop it correctly and go boating.
 

limoman

Seaman Apprentice
Joined
Apr 3, 2012
Messages
38
Re: Fisher Pontoon motor mounted wrong?

Okay I finally brought the boat home and it had one bolt hole I could drop to lower then engine mounting. I dropped it, put a brand new P-13 prop on it and it is a whole lot better. In rough water it still looses bite at times but way better than it was. I am thinking of trying a P-11 prop on it thinking it may make a huge difference? Right now it cruises @ 24 mph at 5,400 RPM's. The RPM's only go higher when it is loosing bite. Just thought I would post what I finally have tried and the results.

Also just FYI. This pontoon has 24 inch toon's on it and sits really high out of the water...
 

Jeep Man

Commander
Joined
Oct 17, 2008
Messages
2,803
Re: Fisher Pontoon motor mounted wrong?

I wonder how you would do with a Bigfoot prop. I have 26" pontoons with a 14x11 prop albeit a 60 hp. It has the same gear ratio as yours I think and it should up your RPMs 3-400.
 

limoman

Seaman Apprentice
Joined
Apr 3, 2012
Messages
38
Re: Fisher Pontoon motor mounted wrong?

I wonder how you would do with a Bigfoot prop. I have 26" pontoons with a 14x11 prop albeit a 60 hp. It has the same gear ratio as yours I think and it should up your RPMs 3-400.

Send me in the right direction and I will buy one and try it. I was about to buy a 11 pitch anyway.
 

limoman

Seaman Apprentice
Joined
Apr 3, 2012
Messages
38
Re: Fisher Pontoon motor mounted wrong?

Okay so if I look at my prop for the rear of the boat the top of my prop is above the bottom of the pontoons. It does great now on smooth water but this weekend it was rougher than normal and it kept blowing out even with the trim all the way down. I have researched the Mercury 5 inch extension thinking this would solve all my problems. I would move the motor back up one notch to where is was factory installed and use this to drop it a lil deeper in the water. I see several 40 & 50 hp motors about the same height as mine but thinking the 115 may be too much for the little bit of water it is biting in to? The extension is around $600 but seems well worth it if it solves my problem. Any ideas? Any reasons I shouldn't? I am in deep water so that won't be an issue.

When I have it WOT the RPM's are @ 5,800 but blowing as much air as it is water.
 

Bamaman1

Lieutenant Commander
Joined
May 15, 2011
Messages
1,895
Re: Fisher Pontoon motor mounted wrong?

All engines have got to be at the correct height before someone can address a propeller issue.

When you're running at normal cruising speeds, you won't be able to even see the anticavitation plate on an engine that's too deep. All you'll see is splashing, speeds will be low, and rpms will be low.

Ventilation is what your experiencing, and it means your engine needs to be dropped. You need to put it down on the transom to start with. Then, see how your boat performs. I wouldn't fool with the engine extension.

I sometimes get ventilation when too many people are sitting in my front seats. I have to move'em to the rear. I really needed to drop my Yamaha 115 hp engine, but I've been dealing with it like this since 1985.
 

limoman

Seaman Apprentice
Joined
Apr 3, 2012
Messages
38
Re: Fisher Pontoon motor mounted wrong?

We dropped it to the bottom hole about a week or so ago. I can have everyone in the back of the boat and it still won't get bite at WOT. I was thinking about the extension and then moving the motor up a few inches. Right now the top of the prop is above the bottom of the pontoons several inches. It does a lot better since I dropped it but still can't run WOT.
 

mtjbrown

Cadet
Joined
Jul 10, 2011
Messages
29
Re: Fisher Pontoon motor mounted wrong?

All engines have got to be at the correct height before someone can address a propeller issue.

When you're running at normal cruising speeds, you won't be able to even see the anticavitation plate on an engine that's too deep. All you'll see is splashing, speeds will be low, and rpms will be low.

Ventilation is what your experiencing, and it means your engine needs to be dropped. You need to put it down on the transom to start with. Then, see how your boat performs. I wouldn't fool with the engine extension.

I sometimes get ventilation when too many people are sitting in my front seats. I have to move'em to the rear. I really needed to drop my Yamaha 115 hp engine, but I've been dealing with it like this since 1985.

So I just had a 75 hp mercury installed on my Fisher 18' pontoon. It will only rev to 2000 rpms under load. Could my motor be mounted too low??
 

mtjbrown

Cadet
Joined
Jul 10, 2011
Messages
29
Re: Fisher Pontoon motor mounted wrong?

I now believe that the motor I have has too big a prop. It has a 21 pitch and my local dealer says it should be 15 pitch.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Fisher Pontoon motor mounted wrong?

So I just had a 75 hp mercury installed on my Fisher 18' pontoon. It will only rev to 2000 rpms under load. Could my motor be mounted too low??

Start your own thread. We haven't finished solving the OP's problem. But since you hijacked this one, you do not have a prop issue and you do not have an engine height issue -- you have an engine problem. It is not running right (probably on only one or two cylinders).
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: Fisher Pontoon motor mounted wrong?

If he's running a 21" pitch prop, he does have a prop problem and may well have an engine problem too. Need to change to a lower pitch and post the results in your own thread..
 
Top