Replacing lifting keel bearing

[cawsandboy]

hi, current bearing on '83 Sun Fizz becomes stiff with lack of use and difficult to move.

Thinking of replacing with nylon/telfon/w.h.y.??   plus stainless core pin.

A good idea?  What's the best advice please.  Want to avoid situation of not being able to lower plate when it's needed most!

Thanks

Cawsandboy

[rene460]

Hi cawsandboy,

I am am not sure what the keel lifting arrangement is on a Sun Fizz, but I assume the usual pin and swinging centreboard. The main variations seem to be in the lifting tackle.

First I would suggest that if it has lasted 30 years, but is a bit worn, I would replace it with similar materials to the original.  Another 30 years would be a good result.

Second, I would think that it would be very difficult to detect a stiff bearing.  I am wondering if you mean the board seems to hang up, and not want to go down.  You might be having to use the push stick more regularly than you would like.  On my SO30i, this tends to happen after a time of inactivity, and it tends to be due to barnacles or muscles growing inside the centreboard case, and getting to the size where the board needs help to go down, despite our best efforts to apply antifouling on the whole board and inside the case.  When the boat is lifted out for maintenance, we use a a stick poked up beside the board to dislodge as many shells as possible.  We usually get quite a pile, and the board moves much more freely when the boat is relaunched.

rene460

[cawsandboy]

hi thanks for your useful tips.
I have since learnt that the original keel hole had become oval over time.  Thus the original materials were replaced with a (larger diameter) steel rod threaded both ends, held in place with an 'external steel' nuts and washers(tack welded) and epoxied over to fair.  There are anodes bolted into the rod ends.

I suspect rusting has occured (rod?) and caused the friction which apparently eases with working.

I want to make a good job so am looking for advice on use of nylon/telfon shims/bearings with a new stainless rod.

Any further suggestions very welcome

thanks

Cawsandboy

[rene460]

Hi cawsandboy,

That makes more sense.  I wonder what the keel is made of in the area of the pin.

The area is immersed, so I would be very cautious about different metals in contact.  My suggestion is that a stainless steel pin would probably be ok providing it is 316, not 304 which will rust in sea water, but Monel would be better and for one rod, well worth the cost in my estimation.  I would then suggest a hard nylon or other heavy duty plastic bearing material, which will also provide an insulating barrier between the pin and the keel/centreboard material, definitely not Teflon which is too soft.  Teflon would be ok for a large diameter washer each side of the plate to keep it centred without adding much friction.  Just check that you choose a bearing material which is suitable for continuous immersion, i.e. does not absorb water and swell when immersed.  Definitely worth some effort to research the right plastic, not just something that someone has spare.

I would then hope that others will buy in to what anode arrangement might be prudent.  But I would look to avoiding mixed metals in contact plus installing the appropriate anode as backup.  This applies to the pin bearing for the board and also to the pin mounting in the boat structure.  If this is also in metal, a further insulating sleeve may be worth while.

I hope that these suggestions are helpful, but appreciate that there may be as many questions as answers.

rene460