When I trim up the front of the boat starts hopping?

[viperbluelx]

05 Stingray 185LX with 3.0 Mercruiser.

If I run around with the trim fully down or very close to it then the boat runs smoothly across the water, if I trim up to where the MPH picks up and the engine sounds better than after a few seconds the front of the boat will start to slowly hop up and down in the water like you're hitting wake over and over, even though the water is smooth. I can put the trim back fully down and the boat smooths back out. I have no idea why it's doing this or if this is just normal? I just bought this boat this year and the first time out I ran up on a sand bar and messed up the prop. I'm not sure if this issue has to do with that or not? The prop is new.

 

[Don S]

Re: When I trim up the front of the boat starts hopping?

You are over trimming back down. Instead of going all the way back down when the bow is porpoising, try trimming down a little bit at a time until the porpoising stops.

 

[viperbluelx]

Re: When I trim up the front of the boat starts hopping?

You are over trimming back down. Instead of going all the way back down when the bow is porpoising, try trimming down a little bit at a time until the porpoising stops.

Yeah, I've tried that, but it doesn't fully stop doing it till the trim is bottomed out.

 

[paultjohnson]

Re: When I trim up the front of the boat starts hopping?

Most people call that....porpoising.... usually it just means you are trimming your engine up too high , You are using your trim switch, not your trailer button ? correct? I dont think its your prop. Have you checked how your trim limit switch is set, maybe its allowing your drive to come up to far. Not sure about your year., but on my 86, the trim limit switch should allow the drive to trim up 6 1/4- to 6 3/4 in, measured from the cylinder end cap to the centerline of the pivot end nut. The trim limit switch adjustment is at the little round plastic cover on the port hinge pin...

 

[stephanies]

Re: When I trim up the front of the boat starts hopping?

Stingray 185's are reknown for this.....post this on the Stingray owners site you will get expert advice...I think "Smart tabs" are the favoured item...

http://www.stingrayboats.com/owners/get_pass.php

 

[QC]

Re: When I trim up the front of the boat starts hopping?

Boat builders are stuck a little on this. The primary cause of Porpoising is weight balance. Typically boats that porpoise are light in the bow and heavy in the stern. The problem is that they are also fastest with the bow up as high as possible at speed. Light bows are easier to get trimmed out/up, so builders tend to lean on the ragged edge. SmartTabs are a great tool to control porpoise, and I am a big fan of all active and passive type trim tabs for v-hulls. I would also consider shifting as much weight forward as possible. and see if it helps. I'd put life jackets aft, and maybe move the cooler up front. Tools in the bow, fenders in the stern. Anchor up front, throwable cushion aft. Yes, add some sort of trim tabs; I think they should be standard. But play with the weight balance too, you may be surprised at the results. Good luck and please report back.

 

[viperbluelx]

Re: When I trim up the front of the boat starts hopping?

Thanks guys, I ordered a set of the Smart Tab SX composite style. Gotta love Amazon for great deals.

 

[tpassmore]

Re: When I trim up the front of the boat starts hopping?

small boats will bounce, period. watch your speedo...as you trim up slightly, you'll increase speed...but trim too high the RPMs increase, speed decreases and bow fluctuates. experiment to find the optimum trim point.

 

[QC]

Re: When I trim up the front of the boat starts hopping?

small boats will bounce, period

Huh? Bounce or porpoise? There are ways to make almost all boats handle safely and properly . . . I have a 14 footer that I can make porpoise and also make it stop, a 17 footer that never porpoised, a 20 footer that was as bad as the OP describes and a 23 that I can make porpoise on the ragged edge and lightly loaded, but usually never budges even trimmed all the way out.

 

[V153]

Re: When I trim up the front of the boat starts hopping?

I ran up on a sand bar and messed up the prop. I'm not sure if this issue has to do with that or not?

Hmm. Well. Did it porpoise before you ran up on the sand bar?

Not trying to be a smart *****. Just that perhaps you damaged the hull?

 

[joe009]

Re: When I trim up the front of the boat starts hopping?

you could also try a hydrofoil.i had the same tbl.and it cured the problem.

 

[JoLin]

Re: When I trim up the front of the boat starts hopping?

you could also try a hydrofoil.i had the same tbl.and it cured the problem.

The Smart Tabs the OP ordered will likely be more effective than a hydrofoil would be. I put ST's on a previous boat and I'm a member of the fan club, too.