Well, most of them are out/dead after a heavy dose of Raid, but I'm concerned about the internals of the deck areas. I'm not sure if the original construction included foam or other material in these areas, or if they're just hollow. If there is foam, should I be concerned that the ants did any damage? I just bought the canoe a couple of weeks ago and it's in great shape (built in 1987), but the ant surprise has put a damper on things. I'll rest easier if anyone here has more in-depth knowledge of the construction in these areas and can comment on whether I need to worry about any kind of damage from the ants. Thanks in advance!

Ive rebuilt a canadienne. The bow and stern have foam as flotation. Nothing carpenter ants would interested in. However the duck plate may be rotting, also the inwalls. Probably not an issue however I would be very careful transporting this canoe, the eye bolt has a very small washer supporting it. If the wood is compromised this bolt could cause the deck plate to break.

I have had ants get into foam insulation in my Alumicraft canoe. If there is access to the chamber that is where they are likely to be. Carpenter ants need a larger piece of wood then a deck plate to live in. If ants can get in there then water can, too. I would check carefully for an opening into the flotation chamber. You can take it to a lake and submerge it. Air bubbles coming out of the edges of the chamber would be diagnostic.

Thanks sedges and jwartman59!
I appreciate the info. Ants are eradicated, and when I knock over the surfaces, it sounds pretty solid. Might do a flotation test later this summer to make sure all good.