[Rhodes22-list] Pictures and details

[BillyDoc]

Hi Rick,

I think you're right about the movement, but I was also looking for
long-term elasticity and rubber is much better for that than plastics.  Most
of the hardware plastic hoses are vinyl in one form or another and they will
take a "set" over time.  That is, they will deform and stay that way. 
Rubber, on the other hand will usually not take a set and will remain
"springy" over long periods.  Rubber is also used in shaft bearings for
inboard motors.  The water makes a fine lubricant in this application. 
Anyway, that was my reasoning.

Bill



Blue Heron wrote:
> 
> Bill,
> 
> You may find the board moves easier if, instead of garden hose, you use
> the
> clear plastic HVAC hose available in any hardware store.
> 
> Rick
> 
> On Sun, Oct 24, 2010 at 11:53 AM, BillyDoc <cushman at cox.net> wrote:
> 
>>
>> I got the centerboard back in the boat yesterday, but still have the
>> furniture to install today.  I just wanted to get this post up ASAP with
>> some pictures, in case they may help someone.
>>
>> When I pulled the centerboard I discovered that the blocks on the
>> trailing
>> edge had pulled out at some previous time and been re-installed roughly
>> an
>> inch lower.  The blocks used were not of the best quality, and I didn't
>> like
>> the installation method very much either (number 8 SS bolt with locking
>> nut,
>> about 1/4" from edge) as it looked like it would eventually pull out as
>> well.  So I fabricated a set of strain plates and installed them on
>> either
>> side of the centerboard using eight 1/2" #6 stainless sheet-metal screws
>> each side.  The plates were fabricated from 316 Stainless, and are 0.030"
>> thick.  The plates were drilled with 1/4" holes to accept 1/4" x 1/2"
>> clevis
>> pins for the upgraded blocks shown in the picture:
>> http://PoiesisResearch.com/Plates.png.  The older damaged areas were then
>> filled in with epoxy putty and sanded smooth.
>>
>> I also wanted to reduce the vertical axis rotational slop at the
>> centerboard
>> pin, so I fabricated the pin shown in the picture (in Anne's hand, also
>> 316
>> stainless steel) with bearing sleeves made from UHMW-PE as shown.  These
>> bearings are set on shoulders machined into the pin and are 1/2" long
>> axially.  The shoulders were polished to make a hard bearing surface, and
>> the external diameter of the bearings forms a snug but not tight fit at
>> the
>> bottom of the centerboard trunk slot.  The centerboard is free to slide
>> laterally on the pin.
>>
>> After measuring my slots, etc., I thought a slightly larger than 5/8"
>> I.D.
>> hose could be used without binding anything and went shopping at my local
>> rubber goods supplier’s shop.  I found a Goodyear product (HORIZON tm
>> 3/4"
>> (19.1 mm) 200 PSI W.P) with an external diameter of about 1.125" that
>> looked
>> good and bought a couple of feet of it to try.  My slots are tapered both
>> fore and aft and laterally, so this hose is tighter near the pivot pin
>> than
>> higher up, which is a nice design feature as it will keep the board
>> centered
>> in the trunk while the resistance to lateral movement will increase as
>> the
>> lateral movement traveling arc increases the contact area in the tapered
>> area.
>>
>> Two pieces of hose were cut just long enough so the bottoms touched the
>> UHMW-PE bearings, and the tops become constrained when the centerboard
>> trunk
>> cap is put back in place.  Picture here:
>> http://PoiesisResearch.com/Hoses.png.  The hoses were simply jammed into
>> the
>> slots from above.
>>
>> We won't get a chance to try this system out this weekend, and since the
>> boat is on a trailer I can't check the play of the centerboard until we
>> get
>> it back in the water . . . hopefully next weekend.  If I didn't
>> inadvertently tangle up the pendant inside the trunk or leave areas
>> unsealed
>> on the trunk cap I expect the "new" system to work well!  I'll post
>> results
>> after we get some testing done, hopefully next weekend.
>>
>> Bill
>>
>>
>>
>>
>> --
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>>
>>
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