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Old 05-19-2016, 01:19 PM   #1
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Cutlass Bearing - Lignum Vitae

Anyone here with knowledge of using wooden bearings (lignum vita)? The shipyard is proposing this with gland water lubrication, but I would be more interested in a dripless shaft seal, which perhaps it is not compatible with.
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Old 05-19-2016, 02:29 PM   #2
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I have heard or perhaps I should say read about it being done back in the day.

But I can't imagine what the advantages would be over modern materials.
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Old 05-19-2016, 02:56 PM   #3
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What Bill said.
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Old 05-19-2016, 04:05 PM   #4
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Many of the old fish boats in Alaska had LV bearings. Re what Bill said perhaps they lasted longer? New tech isn't always better. One would need a wood "deadwood" keel to use LV and the use of stern tubes probably was a limitation too. The small round stern tube kinda begs for a little cutlass bearing.

Don't know anything about life expectancy but they may not be as quiet as rubber. I suspect they last a long time though. I have a piece of LV about 4"x 4" x 3'. VERY HEAVY. Probably closer to cast iron in weight than common lumber.
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Old 05-19-2016, 04:30 PM   #5
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I'm surprised they are suggesting using lignum vitae. From what I've researched, it makes very good stern tube bearings due to the hardness and the natural wood oils provide lubrication. The only problem is cost and availability, as it is now a protected species with international trade restrictions. There is very little left growing in Central/South America.

Sometimes Verawood is used instead, and is called Argentine Lignum Vitae. Although it is almost as hard, it does not have as the same properties as the original. I would think this is what your supplier is suggesting.
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Old 05-19-2016, 10:14 PM   #6
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Why are they recommending this? It's wonderful wood and a very pretty slow growing tree.
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Old 05-19-2016, 10:19 PM   #7
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I used Vesconite, installed in 2006.
It has lasted so far 10 years.
At haulout in 2014, shaft was still tight to the bushing.

https://www.google.com/search?q=Vesc...hrome&ie=UTF-8

Came from South Africa by airmail.
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Old 05-19-2016, 10:31 PM   #8
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The use of wood for bearings went out with "hoop skirts" as my old dad used to say! Very surprised anyone would suggest its use today.
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Old 05-20-2016, 01:21 AM   #9
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It does seem like an odd suggestion in this day and age.

What kind of wood is your builder suggesting for your props?
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Old 05-20-2016, 06:34 AM   #10
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Vesconite people will customize you a bushing if needed, so maybe the wood bush is to accommodate an odd size. They are solid vesconite, so they can be machined to fit. Vesconite is also self lubricating, to a point of course. I doubt it would survive with no water flow in a fast high pressure shaft. But they do make that point.

If you use GFO packing, then you can be dripless with a standard packing gland housing, no need for anything fancy, just better packing. It also lasts a long long time.
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Old 05-20-2016, 06:43 AM   #11
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Use a std old style packing /stuffing box , but install DURAMAX packing or similar and you are done..

No cooling water required , adjust it once , then check every 3 years or so.

Yse it on the rudder packing too.
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Old 05-20-2016, 08:33 AM   #12
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I happen to have a big stick of lignum vitae in the workshop. I made a set of bandsaw blade guide/bearing blocks from it because I couldn't easily find replacements. Fascinating stuff, almost waxy feeling and very hard. Still, I wouldn't use it over modern materials either. I found it gets hot much faster than modern bearing materials and gets brittle.
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