Float tanks/keel tanks

HI all, Im new to the forums but not to canoes. I picked up my late grandfather’s canoe recently. It cleaned up well, and I already knew the keel and stem had significant wear. Looks like it will be a simple fix. I know that anything structural should be done inside, so I may end up needing to remove the tanks.

One question, are the tanks supposed to be airtight? It made sense to me they should be, but a couple armchair folks said they shouldn’t be. Their reasoning was there is foam in them for floating so don’t need to be sealed.

The canoe seems to be a 78 model Yankee Rebel by Sawyer. My great grandmother had a cabin in Oscoda. Great times. I spent a bunch of time in this canoe when young. Its in really good shape. I’m amazed by how well it has held up being stored outside its whole life. It just about got burned up via a grass fire a couple years ago.

Some float tanks have foam inside. This is usually the case for aluminum canoes. IME composite canoe float tanks with foam are usually open topped but you don’t see the foam or the opening because it is beneath a deck plate.

Most of the composite boats I have owned or paddled have closed tanks that do not contain foam. But they usually have something like a vinyl plug with a tiny hole or even just a stainless steel screw that screws into the wall of the tank. Again, you may not see a stopper or screw if it is under a deck plate. The stopper or screw acts as a safety valve to equalize air pressures as ambient barometric pressure changes with altitude and weather, or the temperature and air pressure within the tank changes on exposure to cold water, hot sun when cartopping, etc. Without this the tank would bulge out or suck in the sides of the closed tank as pressure inside varied.

The plug or screw will not admit any significant amount of water into the tank.

My Sawyer Cruiser’s flotation is foam in the ends that has a light fiberglass covering. That covering does not need to be air tight.

I have repaired two Sawyers with foam in the flotation chambers, an Old Town Canadienne and several others. If the chambers are not air tight, then they are not water tight. Water will get in the chambers and have a hard time getting out. Then you get rotted and mildewed foam. It can be a mess.

On a Sawyer Charger, and recently the Canadienne, there was structural damage to the bow stem of both canoes. I cut out the damaged kevlar and foam. Then I sprayed some new foam in the cavity and shaped it. It was easy to perfectly replicate the original shape of the hull with new fiberglass cloth and epoxy. I paid $250 for the Canadienne, after a new wood seat and thwarts, and fresh paint I wouldn’t sell it for less than about $900.

Yeah leaky tanks (all of them eventually) are really the pits. You get water, silt etc trapped in there. Bad for the canoe and foam, not to mention adding weight and giving harbor to invasive species.

Those were my thoughts as well. After long term storage upside down in a sandy area I spent a lot of time blowing out the gunwales and hosing them out trying to get as much sand and other organics out.

It looks like the tanks were sealed, but the way they have “opened” at the seam between it and the hull looked like it could have been intentional. I’m really leaning towards sealing them up when I do the fiberglass repair on the stern keel/stem.