Vibration, vibration, vibration...

[LiFeStArTs@FoRtY]

As the title says, I'm getting some vibration on my new to me Cruisers in my signature.

Symptoms:

Will vibrate at 1200-1400 noticably and at cruise rpm, not as much.
The vibration is like BRRRRMMMM...BRRRMMM...BRRRMMMM. IOW, it pulses for a second on, then maybe 1/2 to one second off. Boat performs well regardless.

What I know...

The PO did great maintenence including gimble bearings on both drives, impellers, greasing, fresh oils, and so forth. Also, within the last year, all bellows on both drives where done. I feel confident that there's nothing wrong with the drives and suspect the props might be out of balance.

I do NOT have counter rotating out drives... they both go the same direction. The props are 19 pitch 4 blade aluminum made by Sola if I remember correctly. I believe these were new in 2001, again going by memory.

I'd like to send these out to get freshened up but can't be without them for that long.

To the pros out there, does this sound like a prop issue or something deeper?

 

[jmarty10]

Re: Vibration, vibration, vibration...

Check the prop. If its bent or chipped a lot replace. Put your spare on the next time out

 

[airdvr1227]

Re: Vibration, vibration, vibration...

Could it be a harmonic imbalance between the RPMs of the twins?

 

[boat1010]

Re: Vibration, vibration, vibration...

I have never delt with twin drives. Can you run just one? Try to narrow it down to which one it is by doing that. And like mentioned before check the props. It is very unlikely it is the props if there is no big chips in them.

 

[LiFeStArTs@FoRtY]

Re: Vibration, vibration, vibration...

I've tried playing with the rpms between the two motors and it doesn't make a lot of difference and in general go by the sync gauge. I've messed with different trim levels and such too. I just ordered new props through Iboats in hopes that I can solve this issue. Otherwise, like I said, the engines run great and the boat performs very well.

 

[airdvr1227]

Re: Vibration, vibration, vibration...

Should be able to. A friend of mine actually installed digital tachs to get his twins running as close as possible to the same rpm.

 

[LiFeStArTs@FoRtY]

Re: Vibration, vibration, vibration...

I don't understand your reply. Should be able to what? Like I said, I ordered new props and will do a full tune up on both engines as a baseline.

 

[airdvr1227]

Re: Vibration, vibration, vibration...

Sorry. I thought you asked if you could run on just one engine.

 

[Thalasso]

Re: Vibration, vibration, vibration...

Take your props and have them laser scanned.had vibration on mine and after props were done not even a movement on the rails.

 

[goboating]

Re: Vibration, vibration, vibration...

This is something to try. If you have a spare prop swap out one engine, take it out and see if the problem goes away. If not then swap props on the other engine and see if it goes away. This could be a quick way to check for a bent prop. IMHO...couldn't hurt.