2018 FSH 210 - Bad Acceleration to plane

[Jetboat4life]

This past weekend the boat would'nt plane like it used to (3 to 4 sec). Now it will just high rev on full throttle..almost like a slipping clutch in a car would feel like. I can go to 5krpm and it will go good..then gradually get to 8k where it still hits 48mph. Ive checked the ports and found no obstructions. What could cause this? I checked the impeller ports and didnt see any visible nicks scratches. Ive got about 110hrs on the boat. This would plane very quickly..now it takes about 10 to 12 sec to get going.

Any help would be great..any questions please let me know.

 

[tdonoughue]

Hey, I had a similar decline (though mine was more gradual). What you describe is likely caused by cavitation before or at the impeller. What year is your boat?

First, check the silicone caulk on the path from outside the boat on the bottom hull up through to the impeller. You are looking for missing hunks of silicone, either the stuff covering the hex bolts, or at any of the seams going up to the impellers. If any is missing or coming out or hanging there, cut it off and smooth the thing out with more silicone caulk.

Then check your impeller. Best to pull the pump (4 bolts from the back, plus disconnecting the steering and reverse cables--pretty simple, despite how radical it sounds). That will let you get a) a good inspection of the impeller (I used a file to smooth out any nicks on mine with good results) and b) get a good inspection of the rest of the jet path for more missing silicone.

Put it all back together, let it dry, and usually you have a brand new boat at the end...

 

[Jetboat4life]

Im going to check the boat today..Im located in Greer, SC if anyone is nearby. I hope this is an easy fix..Im mechanically inclined just haven't messed much with boats.

 

[tdonoughue]

I was amazed at what caulk and a messy finger did for my boats performance. Very easy.

 

[Jetboat4life]

Pics from intake..seems sealant is missing? Cause cavitation? Crazy it’s both sides.

 

[tdonoughue]

Yep, that will do it. Get some silicone caulk and fill that in (along with any other gaps you find or exposed screws or bolts along intake route, like those holding the grate).

 

[Jetboat4life]

3m 4200 good to use? What do you recommend?

 

[tdonoughue]

I used just basic silicone caulk. Thing is that you may need to pull it off someday... Worked for me, was cheap, and I had some in the garage... 4200 wouldn't be bad. But don't do 5200.

 

[Jetboat4life]

Ok..sealant has been added. Hopefully good results tomorrow after water test.

 

[tdonoughue]

Do report back!

 

[Jetboat4life]

Well bad news...still doing it. I’m guess I’m going to have to remove the impeller and all.

 

[tdonoughue]

Yep. Fortunately, pulling the pump and the impeller is pretty easy and allows for a real good inspection.

 

[Jetboat4life]

Pulled both impellers out. No dents. No sticks. I did see scaring where sand is coming through and impellers are hitting sides from sand. I did notice the left side need a good bit more sealant where there were cracks. I guess I’ll take it back out and see if it works. If it doesn’t then the only thing left is the impellers not in spec anymore?

 

[tdonoughue]

You will want that path to the impeller to be a smooth as possible. Looks like where you filled in the gaps you have some roughness--any of those spots can cause cavitation and loss of power. But I agree your impellers look fine. Wish mine looked so good....

 

[Jetboat4life]

I thought they were in good shape as well. Only 44hrs on boat. I figured it needed to be smooth as possible. I’ll have to get it smoother for sure. Any tricks to get sealant smooth? I was doing a water test tomorrow.

 

[tdonoughue]

Only trick that I found was getting really messy with my finger on it. Took awhile to find the right touch (between wiping off too much and leaving too much there so it was lumpy). Does help to put it on as thin as possible--there should be almost none except for in the seam itself.

Don't know how helpful that is, but there you are...

 

[Dixie Highway]

I learned a trick from an old body man, he had the smoothest seam-sealer joints I’ve ever seen. He’d lay a bead of sealant, then coat his finger in rubbing alcohol while smoothing it out. The seams were flawless and the sealant didn’t stick to your finger. Now I do the same thing (with latex gloves on, seems to make it smoother) with caulk, 4200, 5200, etc.

 

[steve0617]

I learned a trick from an old body man, he had the smoothest seam-sealer joints I’ve ever seen. He’d lay a bead of sealant, then coat his finger in rubbing alcohol while smoothing it out. The seams were flawless and the sealant didn’t stick to your finger. Now I do the same thing (with latex gloves on, seems to make it smoother) with caulk, 4200, 5200, etc.

This. I do the same thing with latex caulk when doing the windows in my house. Water obviously for latex, but use non latex gloves and then use denatured alcohol to wet your finger and smooth out your filling in.

 

[jcyamaharider]

The impeller to wear ring gap should be very tight. If it looks about the thickness of a credit card, that is your issue.

 

[Liveto99]

My FSH needs 6000 to plan off, I floor it and then pull back. I am pretty sure it will not plane off at 5k.
To test a boat on outboards we always floored them and saw plain off time you had to to eliminate human error, that way it was always the same WOT. At 48 MPH you prop is fine. Your top speed will drop when there is a problem. I think you need plugs when I had a loss of power that what the dealer told me. And he said do them every 50 hours.