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Cutlass bearing/ shaft bearing noise



 
 
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  #1  
Old August 31st 03, 02:25 PM
Les
external usenet poster
 
Posts: n/a
Default Cutlass bearing/ shaft bearing noise

My friends are having the following problem with noise in their
cutlass (cutless?) bearing:


"After sitting idle in a marina in Turkey for 9 months, upon leaving,
I have this squeal coming out of my shaft/cutlass bearing below 1600
rpm. It peaks in loudness and resonates at 1300 rpm. It stops above
1600 rpm. It does not occur in reverse. I thought it may be coral
growth from sitting still for a long period of time. However, it is
still there after 60 miles of motoring.
The shaft is 1 1/4 " about 32 " long. The stern tube is approx 17"
with the packing gland on one end and bearing mounted at the other.
The boat is a 38' full keel sailboat with an outboard rudder and a 40
hp motor.
The bearing was installed and engine aligned 2 years ago in Trinidad
and logged 500 hrs with no problems. Since then no adjustments have
been made to that installation. Hauling the boat last spring showed
the bearing to still be in good tolerance. I have eliminated all other
possible sources for the noise including the packing gland. There is
no vibration. When I turn the prop manually I can hear a rubber squeak
coming from the bearing/shaft surfaces."

Does anyone have any idea of what the cause of this may be?
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  #2  
Old September 1st 03, 03:41 AM
Snafu
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Posts: n/a
Default Cutlass bearing/ shaft bearing noise

I think you are referring to the stern bearing. That's where the shaft
passes through the hull. The cutlass bearing is in the strut just ahead of
the prop, and is more commonly found on a power boat than a sail boat.

In my opinion, the compression nut should be tightened just enough to allow
a tiny bit of water to seep in when the shaft is turning (and maybe allow a
few drips per minute when the shaft is not turning). This water lubricates
the bearing. I think the fact that the rubber squeaks when you turn the
shaft by hand is not a good sign. I hope the bearing has not overheated and
been damaged.

Dan

"Les" wrote in message
om...
My friends are having the following problem with noise in their
cutlass (cutless?) bearing:


"After sitting idle in a marina in Turkey for 9 months, upon leaving,
I have this squeal coming out of my shaft/cutlass bearing below 1600
rpm. It peaks in loudness and resonates at 1300 rpm. It stops above
1600 rpm. It does not occur in reverse. I thought it may be coral
growth from sitting still for a long period of time. However, it is
still there after 60 miles of motoring.
The shaft is 1 1/4 " about 32 " long. The stern tube is approx 17"
with the packing gland on one end and bearing mounted at the other.
The boat is a 38' full keel sailboat with an outboard rudder and a 40
hp motor.
The bearing was installed and engine aligned 2 years ago in Trinidad
and logged 500 hrs with no problems. Since then no adjustments have
been made to that installation. Hauling the boat last spring showed
the bearing to still be in good tolerance. I have eliminated all other
possible sources for the noise including the packing gland. There is
no vibration. When I turn the prop manually I can hear a rubber squeak
coming from the bearing/shaft surfaces."

Does anyone have any idea of what the cause of this may be?



  #3  
Old September 2nd 03, 06:04 AM
Steve
external usenet poster
 
Posts: n/a
Default Cutlass bearing/ shaft bearing noise

I too have this exact same noise in the same conditions.
If you find the cause and solution, please post it.
I have a Beneteau First 345.
--
Thanks,

Steve Leonard

"Les" wrote in message
om...
My friends are having the following problem with noise in their
cutlass (cutless?) bearing:


"After sitting idle in a marina in Turkey for 9 months, upon leaving,
I have this squeal coming out of my shaft/cutlass bearing below 1600
rpm. It peaks in loudness and resonates at 1300 rpm. It stops above
1600 rpm. It does not occur in reverse. I thought it may be coral
growth from sitting still for a long period of time. However, it is
still there after 60 miles of motoring.
The shaft is 1 1/4 " about 32 " long. The stern tube is approx 17"
with the packing gland on one end and bearing mounted at the other.
The boat is a 38' full keel sailboat with an outboard rudder and a 40
hp motor.
The bearing was installed and engine aligned 2 years ago in Trinidad
and logged 500 hrs with no problems. Since then no adjustments have
been made to that installation. Hauling the boat last spring showed
the bearing to still be in good tolerance. I have eliminated all other
possible sources for the noise including the packing gland. There is
no vibration. When I turn the prop manually I can hear a rubber squeak
coming from the bearing/shaft surfaces."

Does anyone have any idea of what the cause of this may be?



  #4  
Old September 2nd 03, 01:31 PM
Les
external usenet poster
 
Posts: n/a
Default Cutlass bearing/ shaft bearing noise

Steve,

Just received a message from my friend:

"I think I got a handle on this squeal problem. A few days ago I tried
something I have been thinking of doing for a while. It might sound
like a nutty thing to do.

Two 3/8" water circulation holes (port and stb) are drilled just in
front of the bearing as the cutless comes out of the deadwood.
I thought maybe not enough water was circulating to the bearing
because of coral growth on the shaft and bearing within the stern
tube. So, I blocked off one of the holes, fitted a plastic tube
connected to a squeegee bottle that was filled with about a cup of
Muriatic acid. With mask and fins I slowly squeezed the acid into the
hole (and thru the bearing). LOTS of large bubbles flowed out of the
bearing as the coral got eaten. Yesterday we made a 50 mile run to
Fethiye Turkey with only a hint of the problem. I will squirt a little
more in but I think it's solved."

Hope that helps.

Les
  #5  
Old September 2nd 03, 01:32 PM
Les
external usenet poster
 
Posts: n/a
Default Cutlass bearing/ shaft bearing noise

Steve,

Just received a message from my friend:

"I think I got a handle on this squeal problem. A few days ago I tried
something I have been thinking of doing for a while. It might sound
like a nutty thing to do.

Two 3/8" water circulation holes (port and stb) are drilled just in
front of the bearing as the cutless comes out of the deadwood.
I thought maybe not enough water was circulating to the bearing
because of coral growth on the shaft and bearing within the stern
tube. So, I blocked off one of the holes, fitted a plastic tube
connected to a squeegee bottle that was filled with about a cup of
Muriatic acid. With mask and fins I slowly squeezed the acid into the
hole (and thru the bearing). LOTS of large bubbles flowed out of the
bearing as the coral got eaten. Yesterday we made a 50 mile run to
Fethiye Turkey with only a hint of the problem. I will squirt a little
more in but I think it's solved."

Hope that helps.

Les
  #6  
Old September 2nd 03, 03:12 PM
Steve
external usenet poster
 
Posts: n/a
Default Cutlass bearing/ shaft bearing noise

It sounds like a water flow problem. I don't think I have the two holes you
are talking about. My cutlass bearing is in the strut, and the shaft comes
out of the hull. It might be water flow thru the cutlass bearing. Maybe the
front of the bearing got some debris in it and no water is flowing thru the
bearing.

--
Thanks,

Steve Leonard
Barr, Leonard Company
425.641.6844
"Les" wrote in message
om...
Steve,

Just received a message from my friend:

"I think I got a handle on this squeal problem. A few days ago I tried
something I have been thinking of doing for a while. It might sound
like a nutty thing to do.

Two 3/8" water circulation holes (port and stb) are drilled just in
front of the bearing as the cutless comes out of the deadwood.
I thought maybe not enough water was circulating to the bearing
because of coral growth on the shaft and bearing within the stern
tube. So, I blocked off one of the holes, fitted a plastic tube
connected to a squeegee bottle that was filled with about a cup of
Muriatic acid. With mask and fins I slowly squeezed the acid into the
hole (and thru the bearing). LOTS of large bubbles flowed out of the
bearing as the coral got eaten. Yesterday we made a 50 mile run to
Fethiye Turkey with only a hint of the problem. I will squirt a little
more in but I think it's solved."

Hope that helps.

Les



 




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