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Old 21-09-2013, 14:43   #1
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Advantage of the newer cutlass styles

OK I'm new here on this forum.
Im building a wooden boat and the plan calls for a lignum vitae stern, or cutless bearing.
Ive never used that before and it seems improvements have likely been made since this boat was designed (1924). I dont like the idea of just putting the new brass/neoprene style right into the deadwood, so Im thinking of a metal stern tube that the actual bearing goes into. But why even use the rubber style, why not use a bronze bushing?

Thanks!
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Old 21-09-2013, 14:45   #2
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Re: advantage of the newer cutless styles?

Rubber absorbs vibrations better....smoother.
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Old 21-09-2013, 14:51   #3
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Re: advantage of the newer cutless styles?

Ok. But wouldnt it be better to address the vibration at its source?
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Old 21-09-2013, 15:16   #4
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Ok. But wouldnt it be better to address the vibration at its source?
Sure, but first you must find the sewing machine smooth auxiliary Diesel engine.
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Old 21-09-2013, 16:20   #5
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Re: advantage of the newer cutless styles?

Hahahaha Fair enough.

But there is no reason beyond vibration NOT to use say, a bronze bushing?
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Old 21-09-2013, 17:00   #6
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Lignite and rubber bearings are all softer than the shaft to preserve it from wear. I don't know what wear you could expect from a bronze bearing, but I think it would be far greater than that seen with rubber.
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Old 22-09-2013, 10:18   #7
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Just off the top of my head water will work as a lubricant between the rubber & SS shaft but may not work as well on a metal to metal close tolerance fit. A lot will depend on the rpm the shaft turns.
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Old 22-09-2013, 10:36   #8
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Re: advantage of the newer cutless styles?

a common rail engine is butter smooth. say a 2012 VW TDI engine.
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Old 22-09-2013, 11:01   #9
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Re: advantage of the newer cutless styles?

Had a bronze bushing on my last boat (English built trident voyager) the stern tube was filled with grease which would leak out at the bushing. Had to put a turn on a greaser every so often while motoring. Also the bushing had a spiral groove machined in it; I think that was to collect crap and give it a path to exit. It worked well, never wore out in 4 years and over 20Kmiles.

I did have some noise that may or may not have been related ?

New boat has rubber cutless with water lubrication. It was badly worn when I got the boat, now replaced, will see how long it lasts.
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Old 23-09-2013, 08:36   #10
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Re: advantage of the newer cutless styles?

what is the best material for the stern tube? I am considering a thick walled carbon tube.
I will have a 1" SS shaft.
I plan on micro polishing the shaft where it contacts the bushing at the prop end. A bronze oilite style bushing to do the chores.
I have an 8hp farryman.
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Old 23-09-2013, 09:04   #11
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Re: advantage of the newer cutless styles?

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I have an 8hp farryman.

That certainly wont be addressing the vibration at it's source
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Old 23-09-2013, 09:04   #12
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Re: advantage of the newer cutless styles?

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That certainly wont be addressing the vibration at it's source
at 3600 RPM they are very smooth. lol
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Old 23-09-2013, 09:07   #13
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Re: advantage of the newer cutless styles?

We have a composite cutless on our aluminum boat for the obvious reason of reducing corrosion. Sure is easy to get out!
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Old 23-09-2013, 17:42   #14
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Re: advantage of the newer cutless styles?

Also a bronze hush is much less forgiving of minor misalignment.

Regards,
Richard.
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Old 23-09-2013, 20:33   #15
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Re: advantage of the newer cutless styles?

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Also a bronze hush is much less forgiving of minor misalignment.

Regards,
Richard.
Yes l was wondering about that too.
Just have to get it right.
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