Keel bolt bushing

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goldscoter14

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Hi,

I removed the swinging keel from my Snapdragon 23 to find that the bolt had corroded from 20mm to about 11mm. There was no bushing or bearing of any sort in place and I am assuming that it has been in place since the boat was built in '69. In repairing it I am changing the bolt to A4 stainless, but I am having trouble deciding on the appropriate bushing, a bearing being too much unnecessary complication and requiring maintenance.
My local bearing supplier suggested fabricating one out of polymite, but I am also considering vesconite or simply nylon. Another option I am looking at is to use a bushing used in water pumps, which seems reasonable, but I have never heard of anyone using it for a keel bolt bushing.
igus do one at:
http://www.igus.co.uk/iPro/iPro_02_0008_00_GBen.htm?ArtNr=&C=gb&L=en

I was wondering if anyone has experience of a similar problem?

There was an article in a recent PBO on the topic that warned against a brass bushing and recommended plastic with epoxy used to seal it in, but didn't specify what type of plastic. If it wasn't for that article I wouldn't have checked the bolt, and would probably find myself afloat and keel-less suddenly at some stage in the near future!!

thanks in advance,
Danny
 
For any bearings below the warerline the only material to go for is vesconite. Nylon expands in water and will jam.

My propshaft and rudder bearings are vesconite
 
[ QUOTE ]
For any bearings below the warerline the only material to go for is vesconite. Nylon expands in water and will jam.

My propshaft and rudder bearings are vesconite

[/ QUOTE ]
So are mine. www.vesconite.com, or ring the UK number 0800 731 97 45 - last time I wanted some they were able to supply an offcut, which I turned up on the lathe. Very easy to machine, and there's a handy calculator on the web site to work out all the dimensions, tolerances etc.
 
I don't think I would use stainless (a) under the water, and (b) mixing metals with the swinging keel. What's the keel made of? The previous one did very well considering this is a service item that needs periodic renewal.
 
The keel is galvanised steel plate. when it is primed and anti fouled and including the bushing I am hoping that will be enough of a barrier to stop the different metals interacting. What else can I use for the bolt that would last? The previous one was steel, and did well to last considering any protection that may have been on it was well corroded off for the last 20 years or more. I have the SS bar in the post to me now anyway, so will probably go with that. Will vesconite post out? I am living in Ireland, so it would be slightly un-economical to collect!

Thanks to all for your help!
Danny
 
[ QUOTE ]
Will vesconite post out? I am living in Ireland, so it would be slightly un-economical to collect!

[/ QUOTE ]
Yes - at least they did for me. I suppose if you want to be pedantic about this, you should use a hot-dipped galvanised bolt if your plate is also galvanised, but I would think an A4 stainless bolt with a Nyloc nut will be ok. After all, you can check it every year when you haul out. Stainless is only really a problem underwater if it's enclosed (eg covered up in grp). As long as it 'sees' a free flow of water it won't suffer from crevice corrosion, and this should be the case for a pivot bolt, as you can have quite large clearances.
 
Many years ago, had a similar problem on a Jaguar 22. It had a bronze pin through its iron keel, and the hole in the keel had enlarged and become oval.

Anyway, I simply used a length of reinforced plastic hose as a bush, so that the pin was held firmly in place in the keel. All movement was then between the pin and its (bronze) housing in the hull.

Worked very well.

Tony
 
Order direct from vesco on line here

Very hepfull people.

PM me with your email and I can forward you an email with some specials

No connection just happy customer

I dont see too mush of a problem with stainless steel in mild steel keel. Ensured stainless is grade 316 / 304 would do a a pinch but will not last as long as 316.

Also ypu could fit an anode on the keel near the pin to help
 
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