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View Full Version : My boat is "singing"...help!!!???


wishart
06-11-2012, 07:07 PM
Just finishing up a full restoration on my 1982 Stars and Stripes. Have had the boat out about 5 times for "shake down" runs and am down to one last problem before I install the new interior....by boat is "Singing".

At 2800-3000 rpms, there is an annoying noise comming from under the boat...some describe it as "singing". There is NO vibration while this is happening.

If you go into a turn...the noise goes completly away.....Straighten the boat up....noise comes back.

Slow down below 2800rpm...noise completly goes away.

Speed up above 3000rpm...noise completly goes away.

again....no vibration while this is happening...

Thought it might be the prop. I ordered, and installed a new 4 blade prop from OJ props....It changed the noise oh so slightly if at all...but noise still there.


Changed the strut bushings. Since the prop change did not cure the problem, Went after the strut bushings....no change at all with noise.

Checked alignment of engine: After installment of strut after bushing change, I relignend engine...took great care on doing this....NO CHANGE.


Checked prop shaft: When I initally had engine/trans out of boat, I checked prop shaft it is straight.

WHATS LEFT:

RUDDER???

THE THREE SKAGS???


ANY THOUGHTS?????

tph
06-11-2012, 08:31 PM
I was going to suggest prop, because I had a singing prop a few years back that I fixed by filing the edges of the blades. But you've purchased new, so I doubt it's that. In your case, I think it may be the tracking fins.

Jerseydave
06-11-2012, 09:03 PM
My '93 Limited "sings" too. I read on here that sometimes the tracking fins will cause this if they have been polished. Mine were polished from the factory, but they are pretty dull now and it still sings anyway. Not sure if sanding them would help, in my case it might actually make them shinier.

Not sure what to do myself, but I have not tried anything yet. I guess checking to make sure the nuts on them are good and tight is my first step.

keith3613
06-11-2012, 09:11 PM
I had a friend that had a 1982. The fins were making the noise. Just one of those things.

madcityskier
06-11-2012, 09:11 PM
Had a similar sound on a friend's Nautique once. We put duct tape over the fins and it went away. Did one at a time to isolate the culprit. Hit it with a coat of rubbing compound. Repeated about 3x until it went away. Could be that these are all unique problems. The tape was a first easiest try and we got lucky.

CruisinGA
06-11-2012, 09:23 PM
Sounds like harmonic vibration of one or more of the fins with just the right velocity of water rushing by...

Need to change the characteristics of the offending fin(s) to change the natural frequency and get rid of the singing.

Or you could just do what madcity did. :D

Cloaked
06-11-2012, 09:34 PM
Tracking fins. I had 2 - 82 models that did the same thing.

milkmania
06-11-2012, 10:13 PM
can you change the frequency with a rubber mallet?
I figure they're probably Nibral and I doubt they're tuned. I noticed my bolt holes were a little larger than the bolts and could be tweaked a little before tightening them down.

wishart
06-12-2012, 12:45 AM
Good ideas.....

I like the duct tape Idea.....I'm going to try that next.

So....If I can isolate the noise to one of the fins....what is the perminant fix???

polish with rubbing compound???

file the leading edge??

hit it with a mallet....as some suggest....???

Cloaked
06-12-2012, 08:44 PM
Good ideas.....

I like the duct tape Idea.....I'm going to try that next.

So....If I can isolate the noise to one of the fins....what is the perminant fix???

polish with rubbing compound???

file the leading edge??

hit it with a mallet....as some suggest....???Let the fat lady sing. No way to bend or alter those things (within reason).

.

MASTIQUE
06-12-2012, 09:31 PM
Your singing could also be coming from your strut bushing. Hows your engine to shaft alignment?

MASTIQUE
06-12-2012, 09:32 PM
Please ignore my post, missed your comments above...doh!