6 inch waves launch my boat?

[jfrey8899]

Hello. I have a 1971 sea swirl with a mercruiser 140. It is a tri hull. Runs great. Except one thing. When starting to go I would say three quarter throttle the front of my boat starts to bounce and if there is wake in my line of travel it launches the boat totally out of the water. Is this normal. The buttons that raise and lower the motor work and so does the gauge inside the boat. I have messed with it up and down while running and seems to make no difference. Am I missing something. This seems dangerous?

 

[Fishermark]

Re: 6 inch waves launch my boat?

A tri hull is not the best when it comes to waves.... but what you are describing is odd. I would trim it all the way down and then try small adjustments from there.

 

[mphy98]

Re: 6 inch waves launch my boat?

As stated before trim motor all the way down, then adjust upwards. That said, if you have that 140hp on too small a boat or have it incorrectly propped you will have an uncontrollable boat. Back in the early 70's I bought a 72 Slickcraft 16' that was rated for a max hp of 50. I put a 70 on her so I could pull multiple skier's on her. Worked great. Then just for giggles I put a speed prop on her to see what the top would be. A friend owned the marina. It was a scary ride. It was almost all out of the water and wanted to flip on turns. Way over propped and powered. With a power prop it did just fine. So what is that boat rated for and what prop do you have on her?

 

[jfrey8899]

Re: 6 inch waves launch my boat?

Tried looking at serial number plate and Think it only stated weight capacities. Will double check tomorrow as I can't store it where I live. But am pretty sure that this boat and this motor go together. Looks like they were made for each other

 

[danheck7]

Re: 6 inch waves launch my boat?

Just seems like maybe your trim adjustment is not working while under way. You say it makes no difference at all when u use it. Does that mean that it doen'taffect the problem, or it doesn't change anything while you are running. If the former I would try and verify that your trim adjustments while underway are actually moving the outdrive.You should at the very least be able to raise or lower the bow when you adjust the trim.And yes tri hulls are not the best in choopy water, but they are a great stable platform in good water. Wish the wind at your back

 

[Frank Acampora]

Re: 6 inch waves launch my boat?

Simple: Get off the loud pedal when you approach a wake! That is, unless you like being in the air. LOL

What length is the hull?

The bouncing seems to sound like porpoising. That could be too much weight in the stern. Try moving some gear forward. OR, try investing what? about 150 bucks? for the cheaper self adjusting Smart tabs.