The current flotation means are falling out in little white beads in both the stern and bow. These sections are covered by an aluminum plate. Any advice on how to replace this?
You have mice …
I imagine you have figured this out by now, but since no one is offering any advice, here’s some.
You’ll have to drill out the rivets that hold the floatation cover plate in place (some top connections might even be sheet-metal screws). I don’t know where you can buy large blocks of Styrofoam, but you can stack sheets of Styrofoam instead. Cut each layer that makes up the stack to the right shape and you will end up completely filling the floatation chamber with new foam. If it were me, I’d pay more and get closed-cel foam sheets, not sheets of compressed beads, because it will be much easier to accurately cut the shape. A single 4’ x 8’ sheet of Styrofoam, two inches thick, might be enough material to fill both ends but maybe you’d need two sheets.
When you re-instal the floatation cover plate, if any of the drilled-out rivets are below the waterline, Make sure you seal the holes when installing the new fasteners. I’d use stainless steel bolts instead of pop-rivets, but if you’d rather use pop rivets, still use bolts below the waterline for a tighter connection (pop rivets don’t have a lot of clamping pressure, so the only reason to use them when both sides of a connection are accessible is for speedy installation or laziness. Bolts clamp much more tightly so there is less chance of water leaking through).
What brand canoe?
If it is a Grumman, replacement billets of floatation should be available.
Also, try removing the deck plate rather than the bulkhead - no need to seal holes below the waterline.
Good Idea (top plate removal)
Here’s another idea. If it turns out that removal of the cover plate is all that will work (I can imagine that re-attaching the deck might be difficult, due to access problems on the back side), and if some of the existing rivets attaching the cover plate are below the waterline, you could cut the cover plate so that the lower part remains in place while the float chamber is open so no rivets below the waterline are removed. After the removed part of the cover plate is re-attached, splice an aluminum or stainless steel patch across the cut using either sheet-metal screws or pop-rivets. It’ll be as good as new, even if not quite as pretty, and there’ll be no worries about leaks.
2 part floatation foam
I’ve used this before. mix it, pour it into the cavity and let it expand.
You can also use spray, household insulation foam such as Great Stuff. It floats great.