A question on the exisitng holes:
Water has been coming through the holes (hence to need to re-bed). What is the prefered method of preping the holes?
If they are wet TRY and let them dry out over a winter or more then measure them with a Moisture meter. Epoxy, penetrating epoxy and all the other snake oils out there do NOTHING to stick to wet balsa. You are better off to leave it damp and re-bed properly than to try and pot the hole with the balsa wet.
I've seen other threads about wetting them down with epoxy, then removing and filling with thickened expoxy and re-drilling. Others have suggested brilling them out wider first.
The filling with un-thickened then thickened is to allow some fine penetration and a better bond to the surrounding balsa rather than just dumping in thickened epoxy. Think of it as a bonding primer. You then thicken it and have a good base for the thickened epoxy to bond to. Dentists do a similar thing with the polymer fillings. They first bore out the tooth then apply an unthickend priming resin which penetrates into all the small pores. The thickened polymer is then added over the top of the primer/penetrating resin and the filling is then complete after some finishing.
Others mention that acetone will absorb water.
Wishful thinking that in theory sounds good. Acetone poured in between a deck only serves to melt and damage the bond between the balsa and deck skin. Acetone becomes non-fast evaporating between deck skins and actually can become resin eating & softenting. Removing water takes either excavation or many, many, many holes drilled and months of drying. Do the acetone trick on some foam cores and your really screwed.
Keep in mind that with decks that were hand laid, not infused or vacuum bagged, that there will almost ALWAYS be channeling of the moisture meaning that the water is usually more wide spread than just near the fitting as it rides the kerfs in the contour cut balsa or foam.
What do y'all think? (The deck around the track seems sound, so ripping out and replacing all the balsa is not under consideration)
Bed it properly, beveling the holes etc., to stop any more water ingress, and go sailing...
1. Drill out the holes (how larges?)
Personally, I really dislike the over-sized hole method as it breaks the continuity of the top, bottom or both skins. A captured plug is and will be a stronger deck and an over-sized hole. The over-sized hole method to me is a shortcut. I have seen them fail.
These were completely over-drilled and two of the stanchions on this boat broke the "plugs" right out of the deck. I snapped this shot of one of the chunks but this was not even one of the bad ones. There were multiple bad things done in this installation but the reality is that if it was "bored", leaving both skins intact, rather than over drilled, the deck would not have required a massively $$ repair to correct the DIY hack job. This one boat had multiple plug failures and not all were stanchions.
2. Dry with Acetone?
If it makes you feel good you can try it but you may find you have created more trouble than good.
3. Fill with epoxy, then clear; Then re-fill with thinkened epoxy and re-drill?
If the deck is wet just re-bed and stop any further ingress. Potting wet balsa is an exercise "feelings" mostly. If it makes you feel good do it. The bond just will not be there and you will have little epoxy towers between the deck skins that are not adhered. You will see this when you finally have to excavate it.
If the soundings are good and the deck is not dripping brown goo then you'd be surprised how long a boat with wet decks can remain structurally bonded.
If you need a supply of butyl feel free to PM me.