[Public-List] Reinforcing the cockpit sole

[Glenn]

Hi all,  I replaced my cockpit also similar 
In method to what George did. Main difference was I cut my cockpit soul out completely and replaced it with a new prefab Foamcore and FG  piece that fit the dimensions of the cocpit less 1/4" each side. I built the sole in my warm garage with glassed 11/2" x 1" half round foam ribs bottom side of the sole and covered top and bottom with five layers mat and roving.  With 1/2" foam core this was more than strong enuf and turned out I really didn't need the reinforcing ribs as the primary strength of the glassed on sole is the thickness imparted by the foam core and layers of mat and roving. Also the foam core is Impervious to water absorption so no future worries about delamination.

I found It's impossible to properly glass upside down all around the underside of the sole so fiber glassed a 2" lip around the vertical sides of the cockpit to support the new prefab sole and then bedded the sole onto the lip with structural fiberglass putty and tabbed the bottom side where ever I could reach.  Top sides of the sole glassed in with four or five layers of mat and tape. Finished smooth and painted.  Also built a 20 x 18" hatch for rear engine access, and cut an 8" inspection hatch for rudder tube maintenance in the prefab piece.  Overall strong as can be- no stress cracks or movement.  Plus gained a lot of usable and easy access to rear of engine and exhaust system. 

I opted not to use epoxy because of all the glass work. high grade resin was more than strong enough given the FG tabbing and thickness of the deck core. 

Glenn
Dolce 
318

Sent from my iPhone

> On Feb 24, 2014, at 2:21 PM, Gordon Laco <mainstay at csolve.net> wrote:
> 
> Hello George and Stephen -
> 
> I did a cockpit core job in SURPRISE a few years ago.  It was a two day job,
> and not at all as difficult as I thought.
> 
> I cut the top skin off, scrapped out the rotten balsa and the good too....
> Laid in a paste of thickened epoxy then laid a new plywood core.  I drilled
> a 'ton' of 1" diameter holes in the plywood.  I put bricks on wax paper on
> top of the plywood, then started pouring epoxy in until no more would go
> down.  (the bricks are so the plywood couldn't float)
> 
> Next morning I epoxy into any visible dents or voids in what I'd done the
> day before, then covered the whole thing with more thickened epoxy.  Down
> onto that went the old tip skin, with the bricks on top so it wouldn't
> float.  I troweled thickened epoxy into the kerf.
> 
> Later, I sanded and painted the cockpit sole.  I expect I may get tiny
> stress cracks around the edges of the section I cut out and replaced... But
> it's a simple job to paint them again.
> 
> Gord #426 Surprise
> 
> 
>> On 24/02/14 5:12 PM, "George Dinwiddie" <gdinwiddie at alberg30.org> wrote:
>> 
>> Stephen
>> 
>>> On 2/24/14, 3:46 PM, Stephen Gwyn wrote:
>>> 
>>> Hi George,
>>> 
>>> Yes, the cardboard V (or U, or ideally some sort of square shape)
>>> glassed over is exactly what I had in mind. I've also heard of foam
>>> shapes used, instead of cardboard.
>>> 
>>> What I was looking from from the group is whether anybody has actually
>>> done this under and Alberg 30 cockpit sole, and if so, what special
>>> techniques they used to glass to the bottom of a surface in cramped
>>> quarters.
>> 
>> I've not done it, but I can tell you it will be hard to do. Perhaps if
>> you removed the plywood bulkhead to one of the side lockers and worked
>> from there you could reach OK. Be sure to put down plastic sheeting to
>> catch the drips and keep them off the engine and shaft.
>> 
>>> Alternatively, one could imagine a few solid oak beams under the
>>> sole. Or even aluminum angle stock, or an I beam extrusion. One could
>>> steal a section of toe rail off a C&C for example...
>> 
>> How would you fasten those? I wouldn't want to add holes. And the oak
>> would eventually rot.
>> 
>> I redid my cockpit sole, but that was because the core was rotting in
>> the aft area due to water intrusion around the rudder post. Whitby just
>> cut a jagged hole there, and left balsa sticking out to catch any water
>> that seeped under the rudder post fitting. ;-) If you've got that, I
>> suggest trimming the balsa and sealing the edge with epoxy.
>> 
>> I cut out the upper laminate, dug out the core (some of which was the
>> consistency of toothpaste), put in foam core, and laid up new glass on
>> top. The sole is pretty rigid now, but that doesn't mean there's no flex
>> around the edges. A box is not an inherently stable shape.
>> 
>>  - George
> 
> 
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