wood coring question

[Kracker Jack]

Originally Posted by wellcraftv20step

I noticed the 89x27 fuel tank hatch was a bit soft on a corner, so I lifted out the hatch and of course it was soaked and the glass mat was separated from the plywood ! what is the most common material to recore it with today. I was just looking at the Depot website and wondering if the dryply would work since if its laminated properly their should be no water intrusion. the caulking was poorly done and the 2 inspection covers were also not properly fastened.one other thing was that the plywood was not beveled at the edges ,it sat flat against the lip of the hatch which is why the mat on top never adhered to the one inch lip . please give me your thoughts

I used a material called aruaco pine. It passes the boil test,uses exterior grade glue,has minimal if no voids. And is kiln dried. Thats very very very close to marine ply specs for only 35 to 40 dollars a sheet. My ejole boat is built with it.

[tsubaki]

(if I done it right) With shipping charges an 89x27 piece of 3/4" Starboard would run you about $380.
Is this too cost prohibitive?

I'm considering the time and labor involved laminating and such when you might be able to just round the edges, countersink and drill screw holes.

[SkunkBoat]

I have starboard lids inside the cuddy and a starboard cap over the gunnels and I think if they were on deck, where the fuel tank is, they would be trashed.
Great stuff but IMHO not right for that spot.
Also, sealing the hatch would be troublesome since not much sticks(or stays stuck) to starboard. Warping might also be a factor.

Dryply is just sheathing treated for temporary exposure to rain during construction. Not useful for a boat.

PVC sheetboard won't bond with poly resin and probably won't hold epoxy well either.

I know I sound like a downer....

Here are some choices.

Marine grade AB douglas fir ply, $50 for a 1/2"x4x8 sheet at Lowes.(Do NOT use pressure treated pine)
Coosa, $300 for a 1/2"x4x8 sheet...PLUS Shipping.
Seacast or CarbonCore/Arjay/Nidacore pourable.
End grain balsa.
Hexcore or various foam cores.

[wellcraftv20step]

The starboard I know from experience is a no no over the fuel hatch or on the floor anywhere, my v came with a starboard as a replacement for the fuel tank cover .it flexed like crazy even with layers of angle iron on the underside.and I could not find any thing to bond to it as skunk said.i actually started a thread some years ago showing how I built a mold and fabricated a new hatch.i just can't remember what I used for coring , I have my epoxies and cloth material coming from us composites in Florida so I only have a couple of days to get the coring material ...I was thinking dry ply because I've used it quite a bit and generally it's a very good quality and very stable

[SkunkBoat]

Originally Posted by wellcraftv20step

..I was thinking dry ply because I've used it quite a bit and generally it's a very good quality and very stable

Whatever it is coated with will prevent the resin from soaking in and/or bonding. IMO, stick with Marine AB douglas fir.

Where the screw holes will be, use an inch or so of resin/filler and drill thru, so there is no exposed wood.

[wellcraftv20step]

Thanks guys!!

[fixit]

i just re cored my gas tank hatch on my 91 v20... it was 30x32" iirc

i used kiln dried 3/4" fir plywood, exterior grade.

a fair bit of work to cut the core out, grind it smooth, bond ply with Peanutbutter paste, clamped, then three layers of csm over the ply (chamfered the edge with more PB. worked out fantastic! very stiff!