2006 Fastec Vibration
 

Okay folks, I have a new to me 2006 292 Fastec with 6.2's. I had the gimbal bearings replaced, u-joints checked, bellows replaced. Before I put the boat in the water myself. My concern is a significant vibration I can feel as I slow the boat down. The vibration occurs at 20 or so mph and lasts for the count of two or three and then ceases. Before you ask there is no vibration at any other time that I have noticed. Is this something to worry about or is it normal? I'd really like to put this to bed.

It could likely be air becoming trapped under your molded in swim platform, and burping it's way out. Try coming off plane with your tabs all the way down, to keep the transom kicked up a bit. See if it affects the vibration.

If the above ISN'T the issue, then see if you can narrow it down to the port or starboard drivetrain, by bringing one drive back to idle, then shift to neutral while still on plane, and then come off plane as you normally feel the vibration.

We used to own a 292 and never noticed an issue...could it be the stepped hull?

Does it also occur at take-off? I would think a prop imbalance would occur all the time, vs. just when slowing.

I have a 2001 292 and don't think I have had this occur.

You can get prop vibration if you bring your throttles back to idle too quickly while traveling at higher speeds, especially if you are still trimmed out. Engine RPMs slow the props down faster than the water passing through the props and you will get a noticeable vibration for a few seconds.

Do you have silent thunder exhaust?

If the silent thunder dumps out the back and through the drive, yes.

I drop the drives before throttling down. I still may be throttling down to much? I can play with this some next time I'm out. My concern with all of this is tearing the drive/drives up.

Slow your roll JB....come down off plane slower and I am sure you will no longer have this concern.....

Silent Thunder is a non-switchable exhaust that Formula developed years ago. It is a fiberglass box that mounts under the swim platform. If you have switchable exhaust with stainless tips out the back then you do not have Silent Thunder. I only ask as those boxes tend to rattle and vibrate the boat at certain RPM's while coming onto or coming off plane. Regardless, Mentalpause most likely has your solution.

Thanks guys I'll try slower deceleration and see what happens. First twin engine so much to learn.

Enjoy and be safe....