Prop Pitch, motor height, how do I get better performance out of my pontoon?

[edsjr01]

22-23mph would be awesome, but don't be too disappointed if it doesn't.

Keep in mind a lot of this set up is all about compromise. You're looking for a solution that will allow you to do everything you want reasonably well. If all you are looking for is top speed, your ability to pull a big guy on a tube is going to suck! Point being raising the engine is a great plan to get some performance, but it could also get you a cavitation problem in a hard turn or accelerating from a stop. If you change prop sizes and raise the engine all at once, if you have an issue you aren't going to know which is causing it! Baby steps......

Yep, all I really want is it setup correctly which it hasn't been for 6 years. Whatever it does when everything is correct is what it does......I just want it to give me what it's capable of which also in my opinion is best for longevity of the motor and reliability. This was my mother's boat, I just bought it from my dad this spring....he wouldn't let me do any changes prior to me buying it because he was in love with that dealer (he's gotten over that now).

I would say at the 16-17 it's running now these changes have to improve that so in my eyes no matter what the end result is after I do all this I'll be happy. Last night I took it to a buddies and raised the motor 2 spaces. That brings the fin above the cavitation plate up to the bottom of the transom....it was THAT low. Ideally I'm going to test it after that single change...plan was to do that this morning but it's raining (and of course I left the cover off of it)

As for pulling the guy on the tube.....If I want to go tubing (which I love to do) I'll get behind a boat meant to pull a tube.

 

[edsjr01]

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This is before I raised it up with the motor trimmed all the way down....for the first time in it's life because the rocket scientist who installed it 6 years ago didn't take the shipping bolts out.

 

[edsjr01]

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Can't really see it here but that fin is pretty much level with the bottom of the transom. In all reality I think it could probably go up one more but will look at it while running and then decide if it's worth it.

 

[ahicks]

Yup, run it to see where you are. Keep in mind the bottom of that engine pod is quite a bit higher than the bottom of the tubes. Using it to judge where you are at from a height stand point is OK, but the rules that apply to a conventional hull don't always play well here....

 

[edsjr01]

Yup, run it to see where you are. Keep in mind the bottom of that engine pod is quite a bit higher than the bottom of the tubes. Using it to judge where you are at from a height stand point is OK, but the rules that apply to a conventional hull don't always play well here....

That's why I went 2 instead of the 3 that I think it really needs. Dealer told me that plate should be above water and cavitation plate just on top of or just below the water at WOT. He said with it as far down as it was it was likely creating a ton of unneeded turbulence back there and slowing me down. If nothing else, it made it harder to steer which I've actually noticed lately

 

[ahicks]

Infrequently used outboards can sieze up on the steering pin they pivot on. If you haven't recently, maybe time to get the grease gun out?

 

[edsjr01]

Infrequently used outboards can sieze up on the steering pin they pivot on. If you haven't recently, maybe time to get the grease gun out?

Boat is used at least once per week, all grease zerks are hit yearly when I do maintenance

 

[clemsonfor]

Motors are supposed to be set to a certain pulsecurity setting based on the number of cylinders and charge coils on the stator. This is basically manufacturer specific and why mercury told you 6 on that motor.

Something is still wrong if your dealer set it to 5 and you have to subtract 300 at WOT. It's probaly a percentage thing. If your off 7% you won't notice it much at 800 rpm but at 6000 you do. That's just a guess on that cause I am not positive. But if there is an adjustment screw like you said why would you not set it to 6p and adjust it till it's correct?

Somethingis strange there. And like ahicks says if you can get that boat out of the water much when wide open that plate may be too high and cavitate. But you can fix that if that happens easy enough I guess.

 

[edsjr01]

Motors are supposed to be set to a certain pulsecurity setting based on the number of cylinders and charge coils on the stator. This is basically manufacturer specific and why mercury told you 6 on that motor.

Something is still wrong if your dealer set it to 5 and you have to subtract 300 at WOT. It's probaly a percentage thing. If your off 7% you won't notice it much at 800 rpm but at 6000 you do. That's just a guess on that cause I am not positive. But if there is an adjustment screw like you said why would you not set it to 6p and adjust it till it's correct?

Somethingis strange there. And like ahicks says if you can get that boat out of the water much when wide open that plate may be too high and cavitate. But you can fix that if that happens easy enough I guess.

It almost has to be a percentage thing, he told me the issue is with the tach manufacturers. All I know is he put it on 5 and calibrated it using his tachometer tool (he called it something) Mine is this one:
http://www.iboats.com/Sahara-Tach-E...154672--session_id.543710368--view_id.1161500

It's a pontoon, it sits low in the rear and doesn't come out of the water on plane. According to the mechanic where I put it would be a starting point for them if they were mounting a new motor and he said in all reality it might need to go up another. Keep in mind, the original dealer who mounted this motor can't be trusted at all for anything. So thinking that they even looked to see if it was the correct height is incorrect.....yes, they are that bad. Just as an example, would you change the prop on a motor or if you put too small of one on would you adjust the throttle linkage so it cant go all the way to WOT?

 

[clemsonfor]

They should know that prop was not right without even running it? But does sound like the work of a crook of a stealership

 

[edsjr01]

They should know that prop was not right without even running it? But does sound like the work of a crook of a stealership

I think it safe to say that if you have to adjust the throttle cable out to keep from bouncing off the rev limiter, the prop is wrong.

 

[edsjr01]

Just got back from the lake for a quick test after raising the motor and removing the shipping bolts

speed increase of 1 mph
very noticeably easier to steer and drive
did a circle at WOT with no issues in choppy water
overall it rides better and seems to cut the waves better
always before it seemed like it was squatting in the rear, that's gone

The 1 mph increase is no big deal however the issues that it was causing could have effects on what I should gain by adjusting the throttle cable so the throttle is actually all the way open (has to be worth a few rpms) and going to a bigger prop. With this reduced drag I might be able to go from the 9 it has all the way to a 13....gonna try an 11 first.

 

[clemsonfor]

So you adjusted the throttle cable and it's not bouncing off the Rev limiter with the 9 prop?

What's the diameter on this prop?

I have a 2 stroke 60hp evinrude on my 22ft toon it's a crest 2 not the same boat. And it's turning a 13x13 prop.

 

[edsjr01]

So you adjusted the throttle cable and it's not bouncing off the Rev limiter with the 9 prop?

What's the diameter on this prop?

I have a 2 stroke 60hp evinrude on my 22ft toon it's a crest 2 not the same boat. And it's turning a 13x13 prop.

All I've done so far is raise the motor up, I like to do things one at a time and then test just to see what the effect was. Today I'll probably get the throttle cable adjusted and change the prop, haven't decided whether to go with the 11 or 13 on the prop. My motor is a 60 Bigfoot 4 stroke EFI, it uses a 14" prop

 

[edsjr01]

So after raising the motor it likes the 14-11 prop. It's turning about 5900 and running 22 mph with just me in the boat. Raising the motor made all the difference in the world, under full throttle the cavitation plate is just below the water surface. It steers MUCH easier but torque steer was significantly increased, adjusted the trim tab and now it's gone.

 

[ondarvr]

Good job in investigating the issue and getting it dialed in better.

 

[ahicks]

There you go! Pretty nice gains for your trouble it sounds like. Good job!