[Rhodes22-list] Loose centerboard

[BillyDoc]

Greg PA wrote:
> 
> Rummy
> By "metal on metal" I meant were the pin goes though the CB I want to
> epoxy a metal sleeve (ss tubing) into the  CB so the pin isn't in contact
> with the fiberglass of the CB. I guess I could just use PVC pipe instead
> of SS tubing, I thought the SS would be more durable, but I am looking for
> any and all suggestions. 
> 
> After some thought last night I think the larger SS tubing I took out was
> fiberglassed in to the CB originally. The boat is a 1979 and who knows how
> long it took for the tubing to destroy the CB around it. If you look at
> the pictures, the hole in the CB for the pin is enlarged.
> 
> Another factor was there wasn't any hose in the CB cavity (I will be
> adding it). I am on a mooring all Summer, and get a TON of side to side
> rocking from the power boats off the Upper Bay. I need to make the CB as
> stable as possible and keep the side to side to a minimum. I will use the
> CB a lot more sparingly this summer after reading about it here.
> 
> Has anyone come up with a way to add hose to the stern of the CB Cavity to
> really snug up the CB when it is not deployed?
> 

Hi Greg,

Rummy is right, you shouldn't try to install a metal to metal bearing in
your CB.  There are two reasons for this.  First, in all 'plain bearings'
which is what this is, one metal should be soft and the other hard.  This
will prevent galling as the two metals slide against each other.  An example
of this principle can be found in an internal combustion engine.  There, the
crankshaft (hard metal) is usually supported on very soft metal bearings,
and those bearings take a real beating.  The second reason is that two
different metals will invariably have two different galvanic potentials,
even two that are nominally the same alloy, so putting them in a wet
environment makes a battery.  The resulting current flow, ESPECIALLY in salt
water, will eat at least one of the metals in no time at all!  So I strongly
recommend you go with a plastic to re-sleeve your center board hole.  The
best plastic for this purpose is UHMWPE, which you can get in tube form
here: http://www.mcmaster.com/# (and other places).  Unfortunately, you
might have to do some machining to get the right dimensions.

The good news is that I think you will find that the rubber tubes used in
the 'usual' configuration will hold the CB in place very nicely.  Anyway
they seem to do so on mine.

Alas, today is great weather . . . and I need to get my CB trunk sealed back
up.  So, it's take some Motrin and get to work for me!

Bill
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