wood core thickness?

[marionette]

Getting ready initiate some of the core repairs but have not opened up the sealed sardine can of rotten wood. Does anyone know the core thickness around the chain plates? I found prices on closed cell foam and balsa - balsa being only slightly less expensive, so will probably go with the closed cell material. 2 ft X 4 ft section 1/2 inch thick is just under $30.


Runaway
1982 Hull 23

[Jeffrey]

I removed as much balsa as possible with a bent nail and then filled in the void with fibre glass resin and pieces of fibre glass. This makes sure the water intrusion will just go into the cabin and not the core. So unless you have a huge problem you shouldn't have to replace any core around the chain plate. Jeff, Skyhawk #250

[BarryE]

Do like Jeff says; use the bent nail method and route out the core between the glass layers first, check for moisture as you go, with a good drill,a and a selection of different bent nails you should be able to clear out a least an inch or so beyond the hole. Then pack the opening with epoxy,mixed with chopped fiber. Re-drill the chainplate hole through the now solid deck. Unless you've got serious water intrusion through the deck, you shouldn't need to recore. If you do, and really need to, do your cutting from the inside, leave the outer deck, with the non-skid in place.

[dave]

1/2". If you haven't done it already, you would be very wise to go back to the March 21 post "Water in core questions". As with many things that aren't fun to do, it's better to do core repair once, correctly and completely. If you don't it WILL come back to get you with an even bigger more exspensive job! I'm not trying to scare anyone or be a "chicken little", I've just seen it too many times.

Good luck,
Dave

[grandillusion]

another good "hand" tool is a cotter pin tool available in different sizes one from Sears and many from Snap On it looks like an awl with a bent to 90 degrees tip, i have one the has almose a 2 inch reach, if the area is a little larger to repair

[marionette]

Thanks for the tips on the bent nail type solutions for protecting the core when thru-bolting deck hardware. The section I need to perform surgery on is about 10 inches wide and at least two feet long - foreward and aft of the port chain plate. I'd need a pretty wild looking bent nail to do the trick here, so the plan is to peel back the headliner and layer(s) of glass cloth from the inside and relaminate.

As I see it, there are really two options: re-core it - using closed cell foam instead of balsa; or just lay it up with solid glass cloth. Since the area straddles the chain plate hole, it would be best to remove the hardware first and then rebore to the correct dimensions.

The discussion I was hoping to inspire was which route to take - in other words "to core or not to core?"

Runaway
1982 #23

[Tim Bosma]

T
.....
The discussion I was hoping to inspire was which route to take - in other words "to core or not to core?"

Runaway
1982 #23

To core or not to core,
Think of the weight change.
Will the boat naturally list to port when you are done?

[dave]

It's really pointless to consider NOT going back with core, and weight is not the big issue with an area this size, although it of course matters, and I would bet that when you get in there the repair size will grow! If you have to cut out the bottom skin to get to the damaged core, then going back with more core is the QUICKEST and least expensive way to get back to the original thickness and stiffness. Working over your head with resin and glass is no fun. Going with solid glass would mean layer after layer upside down and the cost of way more resin than the original construction would take, plus even soild glass is not as stiff as the sandwich. Also remember, endgrain balsa is the stiffest, strongest and cheapest core that you can buy. Do it right and overdrill and fill [do I hear an echo?] any hardware holes in the new repair and at least THAT section of the deck won't ever get wet again

[marionette]

Well, we have finally put the boat under the knife, cutting away a portion of headliner to get at the wet core from inside the cabin. The area that needs cutting away becomes obvious with the fabric removed since the rotted wood appears to be very dark colored through the translucent fiberglass cloth. Sound (dry) core appears to be much lighter, making the decision as to where and how much to cut away easier.

The core thickness in this section is 1/2 inch. The best tool I found to open up a 10 X 16 inch section is my Ryobi 18V portable circular saw. Just be careful to set the thickness plate to cut through cloth on the lower layer only. The wet core can be cleaned off with a 1 in putty knife.

I'll let it dry out for a week or two, clean the underside of the no-skid, do a little sanding and prep with MEK or acetone, grind the surrounding cloth down to fair / tab in the new. Replacement core is $27.00 for a 2 X 4 ft panel, wood or closed cell foam. I'll stay away from wood to avoid future repairs here. The water came from a small upright deck block with 4 screw holes and not enough caulk. The good news is that once opened, the exposed area seems to be drying quickly.

One more section surrounding the port chain plate and we're off to the races!

"It won't be long now" the Rabbi said as he snipped the little bugger off!

Runaway
Hull # 23