Funny noise

[wumhenry]

Originally Posted by trantor12020

Nope not same. You'll have to grap the prop and lift it up and down. If the cutlass has 1-3 mm play in it, you'll know straight away. You have to get wet unless you intend on hauling it out of water.

If I can move the prop to any extent, that would mean there's too much play in the cutlass bearing?

If there's too much play in the bearing, would the loose bearing make a chattering noise when I'm motoring in a chop even if not when I'm motoring in smooth water?

Pardon my ignorance, but is the cutlass bearing merely a rubber sleeve in the tube that the shaft goes through on the way to the propeller aperture in the skeg?

[Gene T]

I could be wrong but I have never seen/heard of a cutlass bearing only making noise certain times, in my experience if the prop is turning it will make noise, and it will be a drumming, deep knocking sound.

The cutlass bearing is a bronze sleeve with rubber ribs inside, it will be about 6 inches long.

There will always be some play as the rubber will give a bit, but if you move the shaft up and down and you can hear it knock it is bad.

To replace, hall the boat, pull the prop and shaft. Pull the bearing and press in a new one.

[timebandit]

Originally Posted by wumhenry

When motoring in a heavy chop in my Bristol 29.9, I hear a "funny" mechanical noise -- i.e., a noise that isn't present when motoring in flat water. It's not the engine noise, which doesn't change, and seems to be coming from the back of the engine compartment. At first I thought it might be cavitation, but cavitation would be intermittent (I assume), and this is constant. Should I suspect that a bearing is going bad? If it's a bearing problem, why don't I hear the noise during a long motoring run in smooth water? (For instance, the funny noise never cropped up while I motored up the Elk River and through the C&D canal last week.)

Need input----------
Is noise only while motoring in chop--no noise while sailing in chop?
Is noise constant with engine speed-- more rpm and the noise changes?
Is noise the same in F-N-R in the chop?
If the noise stayes the same regardless of the rpm and gear and while sailing in chop then suspect the steering or something not related with the engine or its delivery system.
If the noise changes consistantly with the rpm then suspect eng. trans, shaft, prop. exhaust system etc.
I guess it could be some thing just ratteling around in the chop.
Your knowledge of you boat tells you something is wrong and if you don't listen now she will tell you another way you surly won't like

[wumhenry]

Originally Posted by timebandit

Need input----------
Is noise only while motoring in chop--no noise while sailing in chop?

Yes.

Originally Posted by timebandit

Is noise constant with engine speed-- more rpm and the noise changes?

I think so but not 100% sure at this point. Would have to run field experiment to confirm.

Originally Posted by timebandit

Is noise the same in F-N-R in the chop?

Have no experience with R under relevant circumstances. I don't get the noise in N.

Originally Posted by timebandit

If the noise stayes the same regardless of the rpm and gear and while sailing in chop then suspect the steering or something not related with the engine or its delivery system.

That's not the case.

Originally Posted by timebandit

If the noise changes consistantly with the rpm then suspect eng. trans, shaft, prop. exhaust system etc.

It's not in the engine. It's a noise that's different from the engine noise and comes from farther astern. (The engine noise is no different than usual under conditions that trigger the funny noise.)

Thanks for staying with me on this.

[wumhenry]

Originally Posted by Gene T

I could be wrong but I have never seen/heard of a cutlass bearing only making noise certain times, in my experience if the prop is turning it will make noise, and it will be a drumming, deep knocking sound.

That description doesn't fit. It's more of a thrashing, chattering sort of noise. It sounds like it's made by something that's rotating.

[trantor12020]

Originally Posted by wumhenry

If I can move the prop to any extent, that would mean there's too much play in the cutlass bearing?

If there's too much play in the bearing, would the loose bearing make a chattering noise when I'm motoring in a chop even if not when I'm motoring in smooth water?

Pardon my ignorance, but is the cutlass bearing merely a rubber sleeve in the tube that the shaft goes through on the way to the propeller aperture in the skeg?

If you have lots of play in cutlass, its possible it'll make some knocking noise when motoring hard or into chop. At the prop rotation speed, shaft rocking within rubber sleave could make some noise too. Mine make crocking sound ocassionally. I've about 2mm movement between shaft & cutlass. But my loose prop makes more noise.

[chucklesR]

two cents, and exactly worth it - thrust bearing/plate - whatever they call the part that takes the stress of the shaft /prop. Loose vibrations in chop are being caused by flexing induced by wave action; once it starts it would be continuous based on harmonic's of wave action/RPM yada yada (2 cents don't get much more scientific than that). The cutlass bearing would give the noise no matter what the sea state.
Poking around looking for loose 'stuff' won't find it unless you can poke as hard as the hull flexes in a chop - you'll have to wait until haul out; have a surveyer look at the area and give his/her guesses.

[timebandit]

Try these tests
While in the slip nothing running--turn the wheel as hard as you can.
No noise? should elimenate the rudder and all of it's hardware.

Gain access to the engine compartment and wiggle, shake, push,twist and pull every thing you can on the engine,starter,air cleaner,fuel pump maybe something rubbing on the engind drive or trans output. Check linkages, if you can see it try to move it.
Nothing, eh!
I was worth a try.
Use you eyes and nose. Things that are runing out of lube or aru rubbing usually will turn blue or smell like they have gotten hot.
Now make sure you take off you watch and rings and neck tie and long sleeves.
Start the engine.
While ideling and cold put the trans in f-n-r- any noise. Some times something will show up while cold.
None?
With the engine ideling and warming up touch the NON rotating stuff and feel for grinding and also look and listen.
Put the trans in gear and feel and listen again, one more time in reverse.
If it is inside the boat you should be able to find it.
No luck? Try a little bit of power
Still no luck?
Try taking the boat in calm water. I could be you picked up something on the prop early while running in choppy water and will now show up in calm water.
Time for a swim

[wumhenry]

Originally Posted by timebandit

Try these tests
While in the slip nothing running--turn the wheel as hard as you can.
No noise? should elimenate the rudder and all of it's hardware.

Gain access to the engine compartment and wiggle, shake, push,twist and pull every thing you can on the engine,starter,air cleaner,fuel pump maybe something rubbing on the engind drive or trans output. Check linkages, if you can see it try to move it.
Nothing, eh!
I was worth a try.
Use you eyes and nose. Things that are runing out of lube or aru rubbing usually will turn blue or smell like they have gotten hot.
Now make sure you take off you watch and rings and neck tie and long sleeves.
Start the engine.
While ideling and cold put the trans in f-n-r- any noise. Some times something will show up while cold.
None?
With the engine ideling and warming up touch the NON rotating stuff and feel for grinding and also look and listen.
Put the trans in gear and feel and listen again, one more time in reverse.
If it is inside the boat you should be able to find it.
No luck? Try a little bit of power
Still no luck?
Try taking the boat in calm water. I could be you picked up something on the prop early while running in choppy water and will now show up in calm water.
Time for a swim

It's not the steering.
It never crops up while the boat is stationary.
It never crops up while the boat is in flat water.
It never crops us while I'm sailing with the motor off.
There's nothing on the prop that shouldn't be there.

Maybe Chuckles nailed it.

[soul searcher]

I would think that if the problem were in your cutless bearings that when you are docking the boat and go into reverse with a little headway on that you would hear the same or close to the same sound.
just a thought