Fish Box Lids / Hatch: Has Anyone Ever Opened one of these up. I'm shocked by the core material.

[chbrow10]

So I am the 3rd owner of a 1999 Islander 268. This past year I noticed that one of the fish box lids is soft when I step on it. I do some searching on here and I see that this has been discussed before, but no one every talked about re-coring one or opening it up. It seemed like folks just added another layer on to the bottom "skin". Or bought new ones.

I decided to do some exploratory surgery and used a hole saw without the centering drill bit. The core material appears to be some kind of fiberboard. It is wet, and now looks like cardboard. I am stunned that Grady would used something like fiber board witch absorbs water like crazy, and once wet, looses all structural integrity. And in my case, debonds to the top skin. It appears that the bottom skin is just formed putty.

Here is a picture. You can see the shredded material. Nasty.

Has anyone ever repaired these?

 

[Ozz043]

I would say that this would be common practice in the industry, it’s not supposed to get wet but ....
Ply is no different when it’s wet really ....

 

[SkunkBoat]

In fishbox/coolers in other brand boats I've seen foam sheet used as the core material for insulation.
In theory, the core doesn't need to be terribly strong, its the glass surrounding it and bonded to it that makes the strength.Of course, once the core gets wet and the bond is lost, there is no strength at all.

I have recored hatches. Its pretty easy and all the work is hidden on the bottom side. The visible side is untouched. Just cut thru the bottom skin, dig it all out, grind it clean and start fresh.

Epoxy will give you a better bond than polyester resin but its more expensive. Also, you can use epoxy over the pink insulating foam if you want to go that route. Polyester resin will melt pink foam board.
If you use plywood, don't use pressure treated. Get Douglas fir exterior grade AB plywood (aka Marine Grade)


Oh, just looking at the picture again. If you cut the bottom skin off in one piece you'll have a nice thick sheet of glass to use as part of the re-skin.

 

[chbrow10]

I would say "common practice" is end grain balsa core or plywood. Not fiber board. I understand that the core only needs to transfer shear forces to the skins, but when its wet, and fiber board is highly hydroscopic, you can forget that. And the bottom skin in this case is just a layer of 0.13" putty. Wet plywood performs way better (I know from recoring the main tank hatch on this boat).

Heck, even my 1973 Mako 20 center console had end grain balsa core. We're talking about a Grady, for pete's sake.

 

[chbrow10]

@ SkunkBoat: That bottom skin is NOT "a nice thick sheet of glass ", its 0.13" (one eighth of an inch!) of formed putty, with ZERO structural reinforcement.

 

[SkunkBoat]

@ SkunkBoat: That bottom skin is NOT "a nice thick sheet of glass ", its 0.13" (one eighth of an inch!) of formed putty, with ZERO structural reinforcement.

yeh, interesting material choice. Must have something to do with insulation for fishbox. So the thickness of the sidewalls is glass and that thickness follows around to the top?
My only thought is that the top glass was made thick for structure and they just sprayed gelcoat over the bottom.
That lid is a deck piece? or its the top of a seat?

 

[Privateer]

It looks like OSB which typically has a waterproof glue but the wood itself is not treated.

 

[chbrow10]

yeh, interesting material choice. Must have something to do with insulation for fishbox. So the thickness of the sidewalls is glass and that thickness follows around to the top?
My only thought is that the top glass was made thick for structure and they just sprayed gelcoat over the bottom.
That lid is a deck piece? or its the top of a seat?

This is the lid to the starboard fish box, which is also a walking surface/deck piece. Today I got the bottom skin off, removed the wet core, sanded the bottom of the top skin, and bonded in the new core (1/4 " plywood). Tomorrow, Son#2 works at West Marine and will bring home some more resin and I will finish the new bottom skin, which will be 4 plies of 1.5 oz CSM and a 10 oz square weave surface skin.

 

[Neckbone]

Resurrecting this thread as I just picked up a 1996 268 islander that has a few soft hatch lids (Bilge access/rear seat, port corner hatch, and port fish box/livewell lid. At first glance these lids don't appear to be cored.. How did you go about removing the bottom skin> The lids seem to be relatively thin without any obvious raised core area to start digging at..

 

[SkunkBoat]

Resurrecting this thread as I just picked up a 1996 268 islander that has a few soft hatch lids (Bilge access/rear seat, port corner hatch, and port fish box/livewell lid. At first glance these lids don't appear to be cored.. How did you go about removing the bottom skin> The lids seem to be relatively thin without any obvious raised core area to start digging at..

pix please

 

[Neckbone]

pix please

will do as soon as I get off of work (and if this rain ever stops)