[Rhodes22-list] Loose centerboard

[John Shulick]

BillyDoc,

 When I rebuilt my centerboard and trunk I had a friend machine me a new pin
of 1/2" 306 stainless and a yellow brass bushing 1/2" ID and 1 1/2" OD.  I
used a hole saw (goes on the end of a drill used normally on doors and such)
on the centerboard and then epoxied the bushing in the centerboard. I have
been using this set up for 3 yrs with no problem. BUT I am in a fresh water
lake and not the ocean. Also my boat is in the water only half the year as
well. 

John S




BillyDoc wrote:
> 
> 
> 
> 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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