Replacing mushy core from inside cabin

[dralex]

Hi;
I purchased Ariel 24 last fall and have been poking away at assessing small areas of mushy core, mostly around the stanchion and ranging from 6" wide to 1 foot. I started removing the inner (cabin side) skin around these areas until I reached intact core, and will soon be ready to install new core and repair the inner skin.
Does anyone have advice re glassing from the inside? I will need to use new materials as the old inner skin was damaged/destroyed during removal. I was thinking of doing two layers of fibreglass on a sheet of new core in the garage, then using the resulting material to cut pieces to fit the spaces near the stanchions. Then, using thickened epoxy, install these new pieces with braces to apply pressure. After that the gaps would be glassed over with two layers of strips of cloth and the cabin ceiling faired.
Also, since these areas seem prone to water infiltration, it seems wise to me to use foam instead of balsa. Comments?
THanks!
Alex
Ariel 24

[Rachel]

Here are a couple of threads that will give you some information:

http://plasticclassicforum.com/viewtopi ... deck+below

http://plasticclassicforum.com/viewtopi ... deck+below

I re-cored portions of my former boat's deck from below. It wasn't all that fun working against gravity, but the decks were perfect, and the interior had no liner or finish to speak of.

I used a combination of blue tape and plywood-and-sticks to hold up the new glass while it cured. Most of the core stayed up just with the thickened epoxy I used to bed it.

Rachel

[Quetzalsailor]

It would not hurt to use chunks of solid fiberglass for the core at the load points. Buy the stuff at McMaster Carr, or lay it up yourself. The rest of the panel can be the foam.

[bcooke]

Also, since these areas seem prone to water infiltration, it seems wise to me to use foam instead of balsa. Comments?

'These areas' are only prone to water intrusion because the fittings were installed incorrectly in the first place. Since you are going to do it the right way the core material is not going to be an issue.

Foam might not rot but water that gets inside will still get into the crevices, freeze, and bust apart anything in its way. Foam is a marginally better core material but certainly not a huge improvement in this application. Done right, balsa works just fine and will last forever. My 40+ year old balsa core in the deck is as bright and fresh as the day it went in; except where some bozo drilled holes through the deck and didn't properly seal the holes.

I was going to reinforce some of the deck core with solid fiberglass where I had some high load fittings but was dissuaded after a discusion on this board about a year ago. Unless you have signs of failure or stress I wouldn't worry about reinforcing an area that is already strong enough.

[catamount]

I did some re-coring working for the inside, working over head, on one of my projects, as documented here: http://sailing.thorpeallen.net/Quasar/

I found that spring poles or clamps weren't necessary for holding the new coring in place -- as long as the epoxy was thick enough the stuff would stay up by itself (the bonding might have been better with clamps, though).

For laminating the fiberglass skin working over head, I found it important to give the epoxy a couple of minutes to set up before trying to stick the glass up into it -- if it's too liquid, the glass will just fall down under the influence of gravity, but just before the epoxy starts to kick, the glass will stay up.