[Public-List] Cockpit deck core job

[Don Campbell]

A few very necessary basics to remember:

    Fixing a fix is more expensive and often much more difficult than 
doing it right the first time.

    If you start a job, finish it completely and do it well to avoid 
fixing a fix.
 
    A truss is only good if it is rigid, so anything that aids 
rigidity,  especially in areas designed to carry weight and not flex, 
like cockpit soles, is better with more not less, so tabbing should be 
considered. It is not expensive to do and is one of those things that 
one ought to question about the original. Did the system fail or 
partially fail because of a lack of strength or tabbing in the first place?

    Then bonding epoxy to polyester is always a concern and great care 
needs to be taken to make sure there is ample mechanical grooving to 
increase surface area between the  two. 50 grit or larger abrasives are 
necessary here. Any weakening here will compromise the truss rigidity 
factor that is intended from a rigid layer below and a rigid layer 
above. The rigidity is the result of the bonding. If the bonding fails, 
the truss has failed. Chopped mat scrims also play a role for added bonding.

    The next is that polyester is not waterproof and epoxy is much more 
so, so if there are weaknesses in the epoxy in the core, they will 
ultimately get wet when the cover is polyester. Therefore consideration 
of replacing the polyester cover should be undertaken if waterproofing 
is a concern.
 
     Epoxy is not UV stable so if you have left any exposed epoxy in 
joints or cracks, and UV does hit it, you will have a breakdown in the 
epoxy product. Any direct sunlight is all UV radiation, winter or summer 
or anywhere in between.  If UV  degradation weakens the joint, then the 
truss is weakened too.

    There are steps that do need to be followed and those includes 
covering all sun exposed epoxy asap. The easiest is to use a quality 
deck paint and for cockpit soles some grit is nice. I suggest that 
Sikkens deck paint is a good,  cheap product for this and can be 
obtained from any Nobel-Axel dealer. It gives you time to make a more 
expensive decision (if you want to) without compromising the strength of 
your epoxy work. However, recovering deck paint with the deck paint 
again is still cheap and easy. (Use of these products will mean that you 
cannot use bare feet as the best footwear and you will not want this on 
the benches. I have used it on Y-flyer decks and it wears the seat of a 
pair of pants threadbare every weekend regatta.)
Don
    

Rachel wrote:
>
> On Apr 8, 2010, at 8:29 AM, Gordon Laco wrote:
>
>> Hi there -
>>
>> No, I didn't tab the wound... Time will tell if I should have heeded
>> published advice.
>
> Hi Gordon and thanks for responding.  I thought I was inferring from 
> what you said but was still curious.
>
> I would definitely tab the "seam" because the top skin's continuity 
> really helps with the strength, along with keeping the crack from 
> making itself known. Granted, your cockpit sole is not likely to 
> collapse as-is, but just, after the work you've done I would want to 
> get the tabbing on too.  That said, one of the wonderful things about 
> boat ownership is that it's one of those areas in life where people 
> can still do as they see fit -- may that never change!
>
> Rachel
> ex-#221
>
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