Noisy Drive shaft and Prop

[Peter B]

Hi< I am a new subscriber from down under. I Purchased my 1988 "Threes Company" 799 about 2 years ago, slipped it for second time last month. Used usual anit foul, new anode and my painter used a new product from New Zealand called "PROPSPEED" on the drive shaft and three blade prop. It's a clear finish, coloured only by the under coat. Boat back in the water and coincidently scretching noise at 13 to 1600 RPM. Drive through it and it's gone. Motor is Universal M25 with usual vibration at low RPM. I could not let it go so I slipped it again because the noise seemed to eminate from the skeg bearing. This was replaced by my mechanic along with stern gland. Guess what the noise a little louder but now at about 16 to 2000 rpm. Mechanic baffled and I don't want to go on expidition without knowing what I am dealing with.
Has anyone out there got any clews.

Peter B. Sydney Australia.

[Ron Hill]

Peter : Did this noise also occur before the shaft/prop were painted ? 
If it only happened after, I'll wager that some of the cleaning solvent, primer and/ or paint may have migrated into the cutless bearing.  How old is your cutless bearing ?
Strange - Still thinking.   

[Ray & Sandy Erps]

Hello Peter,

I have a dripless shaft seal on my boat.  If I don't burp it after hauling it out or doing some scrubbing underneath using my SCUBA gear I used to get a horrible noise at higher RPMs.  It was the carbon seal chattering on the stainless seal and propellor shaft.  Once it was burped (clear the air pocket by allowing a little water to flow by) the noise would disappear.  Just another idea.

[glwestcott]

Hi Ray,

Last year I bought my 94 34 back from the guy I sold it to in 1999.  He kept it in great shape and updated lots of stuff including all the canvas.  Great deal!  Anyway, he also put a PSS dripless stuffing box on which I like a lot.  However, after running at higher rpm for awhile I also got a terrible noise.  Dropped the rpm and it stopped.  Ran the boat back to higher rpm and it was fine for awhile, but then began again.  I was quite worried and checked everything, but couldn't find any problems with shaft, alignment, transmission, etc. and thought it probably involved the shaft seal.  Now, with your post, I understand what is happening.  Thanks!  Any specifics on how to go about the "burping"?  I presume, simply loosen the seal to allow a bit of water to flow through and then retighten.  Is that correct?

Gary

[Tom Soko]

Gary,
It's even simpler than that.  Pull the rubber bellows aft for just a second and release it.  A cup or so of water will spurt in, and you're done.  As was mentioned, this should be done every time the boat is launched, and/or after a diver has cleaned your bottom.  Water lubricates the two surfaces (the SS donut and the ?graphite? seal).  Without water lubrication, the increased friction could score the surfaces.  Extended high speed running without water could melt things together, according to the directions that came with my PSS, and cause catastrophic failure.  I believe that PYI only sells the "high speed" version of the PSS now, which includes a nipple tapped into the graphite seal for attaching a small hose, which makes the unit "self burping".  In this case, my mother is wrong.  Burping  is good!

[glwestcott]

Tom, thanks.  I'll give burping a try!  I know it worked on my kids when they were many years younger.

[Peter B]

:cry4`Thanks to those who replied to my dilemma of a noisy, squeal in my propshaft. Iam a new user and had a lot of trouble working out the how to find the messages. The upshot is I am not sure if I got them all. (found 2). All the suggestions where checked prior to launching boat and bellows burped. To reiterate. Squeal comes in at about 1500 rpm and goes at 2000rpm. I can eliminate the squeal by driving hard through the range, but as soon as I de-accelerate the noise comes in. It's very frustrating. Further suggestion appreciated. Peter B.

[Ron Hill]

Peter : Re check your answers again.  I still suspect that it's your cutless bearing.   

[Peter B]

Ron,  :cry4`thanks for your interest.I have a question. What do you call the "cutles bearing"?
For your info I replaced the what us Aussies call the Skeg bearing, out side near the prop. I also had the stren gland replaced, inside behind the motor. The one with the bellows that needs burping. Also this new antifoul called propspeed is applied by clean- ing off everything and etch priming followed with a coat of propspeed. The finished job is clear. The color give by the primer makes it look like gold. The feel is tacky, although it's dry. The KIWI's use it a lot. Thanks Peter B.

[Roc]

Peter,
The high pitched squeel you hear may be coming from the prop.  I had a high pitched noise at the same RPM's.  I found that once some slime accumulated on the prop (after the boat being in the water for several weeks), the noise went away.  I was first told that the noise was due to the blades being 'too sharp' when the prop was reconditioned (the noise happened after my prop was reconditioned, before that there was no noise).  Too sharp meaning the edge of the blade was too pointed and it should have been flatter.

So, since the noise did go away, I figured I'd let it go until I had the prop serviced again.  Last year I sent my prop to Black Dog propeller in Maryland.  I told them about the high pitched squeel (kind of like a tuning fork noise).  They said the noise was due to the prop being out of balance.  I guess they were right, because when I got the prop back from them, and tried it last season, there was no noise.

So how can a prop be out of balance right after it was reconditioned???  Well, the yard that did the job 'blocked' the prop when installing it ( I saw them do it), so they knocked it out of balance the moment it was installed.  When I installed mine last spring after Black Dog balanced it, I took Ron's suggestion and just held the prop with one hand while tightening the nut.