Hello all.
I have a 34' aluminum sailboat hull that was built some time in the
late 1970's but never finished until now. The stern tube is sch.80
aluminum pipe and was welded by the builder, my question is two fold,
first does any one know of a cutlass bearing to fit pipe approx 1.9".
And second the stern tube seems too be a bit oval, maybe (3/64"-1/32")
probably from welding. Any suggestions?
Thanks Paul

I'm not sure of how you deal with the dissimilar metals in an aluminum hull,
however all the standard cutlass bearings I have dealt with had a bronze
outer shell. Seems like a problem waiting to happen.

I would think you would want to fit a none metallic insulator between the
two.

For a boat this size, you should be looking for a shaft size of at least
1.125" so that only leaves you 0.3875 clearance for the bearing shell and
rubber material.

I would recommend you look through some standard cutlass bearing specs and
see if there is anything close, if you have the existing tube line bored
in-place, to the closest fit.

Otherwise you might consider welding in a new stern tube that will fit your
shaft and cutlass needs.

My opinion and (limited) experience. FWIW.

Steve
s/v Good Intentions


"Paul Baker" wrote in message
om...
Hello all.
I have a 34' aluminum sailboat hull that was built some time in the
late 1970's but never finished until now. The stern tube is sch.80
aluminum pipe and was welded by the builder, my question is two fold,
first does any one know of a cutlass bearing to fit pipe approx 1.9".
And second the stern tube seems too be a bit oval, maybe (3/64"-1/32")
probably from welding. Any suggestions?
Thanks Paul

"Paul Baker" writes:

I have a 34' aluminum sailboat hull that was built some time in the
late 1970's but never finished until now. The stern tube is sch.80
aluminum pipe and was welded by the builder, my question is two fold,
first does any one know of a cutlass bearing to fit pipe approx 1.9".
And second the stern tube seems too be a bit oval, maybe (3/64"-1/32")
probably from welding. Any suggestions?

Make sure you get a cutlass with a non metallic outer shell.

I had to special order mine.

HTH

Lew

Paul,
I must admit that I am confused. Stern tube? Cutless bearing? They do not go
together. The cutless bearing goes into a P bracket which supports the
propeller end of the shaft. I have assumed that this is center fin design
and if it is, the propeller is positioned between the fin and the rudder. In
that design, the stern tube supports a packing gland only, not a cutless
bearing. Please keep in mind that water flow lubricates a cutless bearing,
which dictates that the forward end of the bearing is exposed to the sea. If
your hull design dictates a propeller at the rear of the fin, then you must
use a grease lubed conventional bearing on the sea end of the stern tube.
Steve

"Paul Baker" wrote in message
om...
Hello all.
I have a 34' aluminum sailboat hull that was built some time in the
late 1970's but never finished until now. The stern tube is sch.80
aluminum pipe and was welded by the builder, my question is two fold,
first does any one know of a cutlass bearing to fit pipe approx 1.9".
And second the stern tube seems too be a bit oval, maybe (3/64"-1/32")
probably from welding. Any suggestions?
Thanks Paul

Paul Baker wrote:
Hello all.
I have a 34' aluminum sailboat hull that was built some time in the
late 1970's but never finished until now. The stern tube is sch.80
aluminum pipe and was welded by the builder, my question is two fold,
first does any one know of a cutlass bearing to fit pipe approx 1.9".
And second the stern tube seems too be a bit oval, maybe (3/64"-1/32")
probably from welding. Any suggestions?
Thanks Paul

What is your shaft size? - if ~1" then you could fit a cutless bearing
with a 1-3/4" OD. Pack the ovalized gaps between with epoxy thickened
with microfibers. Coat the cutless bearing with a few layers of mylar
packing tape else you will never get it out!

Otherwise, remove the distorted one and re-weld in a round one.

As others have pointed out you should use a bearing with a fiberglass
shell, not bronze. Not as common but they do exist.

Evan Gatehouse

Steve Lusardi wrote:
Paul,
I must admit that I am confused. Stern tube? Cutless bearing? They do not go
together. The cutless bearing goes into a P bracket which supports the
propeller end of the shaft. I have assumed that this is center fin design
and if it is, the propeller is positioned between the fin and the rudder. In
that design, the stern tube supports a packing gland only, not a cutless
bearing. Please keep in mind that water flow lubricates a cutless bearing,
which dictates that the forward end of the bearing is exposed to the sea. If
your hull design dictates a propeller at the rear of the fin, then you must
use a grease lubed conventional bearing on the sea end of the stern tube.

Must take exception to the above.

My hull is a fin keel design if you want to call a 21 ft long keel a fin.

The stern tube exits the rear of the keel and contains the cutlass.

The stuffung box has a water injection port.

Cooling water from the raw water pump supplies positive pressure raw
water to the stuffing box to keep the stern tube filled and the cutlass
bearing lubricated.

HTH

Lew

Evan,
Welding a stern tube in place will almost always cause cupping and
distortion because of diagonal nature and the length of the weld. When I did
mine, I used a much larger tube for welding, Then suspended a straight tube
within the welded tube and filled the space between the two with casting
plastic, which is used to make engine mounts on large ships. The inner shaft
tube is supported inside the hull by a thrust bearing assembly and outside
by an integral P bracket. In my case, I used a oil pressure fed bronze
bearing & lantern ring assembly followed immediately by a packing gland with
a compression ring. These are positioned directly under the P bracket at the
rear end of the tube.
Steve

"Evan Gatehouse" wrote in message
...
Paul Baker wrote:
Hello all.
I have a 34' aluminum sailboat hull that was built some time in the
late 1970's but never finished until now. The stern tube is sch.80
aluminum pipe and was welded by the builder, my question is two fold,
first does any one know of a cutlass bearing to fit pipe approx 1.9".
And second the stern tube seems too be a bit oval, maybe (3/64"-1/32")
probably from welding. Any suggestions?
Thanks Paul

What is your shaft size? - if ~1" then you could fit a cutless bearing
with a 1-3/4" OD. Pack the ovalized gaps between with epoxy thickened
with microfibers. Coat the cutless bearing with a few layers of mylar
packing tape else you will never get it out!

Otherwise, remove the distorted one and re-weld in a round one.

As others have pointed out you should use a bearing with a fiberglass
shell, not bronze. Not as common but they do exist.

Evan Gatehouse

That's something I hadn't heard of but now that we are discussing this
problem it seem the industry has met the need.

Steve
s/v Good Intentions

"Lew Hodgett" wrote in message
nk.net...
"Paul Baker" writes:

I have a 34' aluminum sailboat hull that was built some time in the
late 1970's but never finished until now. The stern tube is sch.80
aluminum pipe and was welded by the builder, my question is two fold,
first does any one know of a cutlass bearing to fit pipe approx 1.9".
And second the stern tube seems too be a bit oval, maybe (3/64"-1/32")
probably from welding. Any suggestions?

Make sure you get a cutlass with a non metallic outer shell.

I had to special order mine.

HTH

Lew