So, we bought an old Alumacraft QT17 from neighbor for a song. I love that boat as that is what I grew up in. One problem: the styrofoam that is enclosed in the bow and stern is rotten and the little beads wash out of there and make a mess. The worst part, though, is that they get water-logged and are heavy when wet. Anybody ever cut their way in, remove the old styrofoam flotation and replace it with blown in foam or anything like that?

I am not an expert but I wonder if you could use air from a compressor to blow out the loose stuff ???? Then what about that insulating spray foam that folk use for windows and doors? I looked at mine just now....4 rivets hold that plate in but I sure would not want to remove them...A guy could consider bending that plate back a bit to see that you are dealing with and blow out the loose stuff..............

I don't have an Alumacraft but if yours are riveted on it's pretty easy. I have removed both the bow and stern cover plates on my Osagian several times. No big deal at all, drill the old rivets out and replace with aluminum rivets. One possibility on replacing the flotation is to get a block of Styrofoam or glue some together into a block.

Thanks guys. Replace with aluminum rivets...I have never used a riveter thingy; is it pretty simple? Can a person rent one?

A rivet tool is very easy to use. You first drill out the old rivet. If you used a 1/8" drill bit to drill the old one out, you would use a 1/8" new rivet to reinstall. The new rivet should just fit the hole diameter.
You can buy a rivet tool pretty cheaply. Here is a link to a rivet tool with rivets.

Like others, I wouldn't hesitate to drill out the end panels and re-rivet them in place... You'll want a solid rivet as pop-rivets will likely leak

as for the foam debris.. the only time I've personally seen this is when the canoe had previous mouse damage... they get in there and setup a nest in the foam.. so, don't be surprised by what you find... if you spray foam in there, get the low/no expanding variety and think about how/when to install the end plate.

As others have said, it's not hard to remove the rivets and panel and then re-attach. Osagian Canoes even has a helpful how-to video: https://www.youtube.com/watch?v=QU0oRLR1qHs

As for the foam, you could try contacting a local Alumacraft dealer to see if they could order the foam part for you. I had good luck looking for canoe parts with Dan's Southside Marine in Bloomington.

I had the same issue with one of my Grumman Sport boats. Believe it or not, ants took a liking to the foam floatation. I kept seeing ants on the boat after I bought it. The bow plate is bolted in on these boats, so I removed the plate and the two part Styrofoam floatation. The ants had it all honeycombed out with a hole the size of a basketball in the center.

The fix? I bought this: Two part marine foam

You mix the two parts then pour it in and it foams up. I did both the bow and under the rear seat. It's specifically made for boats. For the bow floatation, I mixed it and filled all the voids that the ants created. For the rear seat, I removed the old floatation, lined it with a plastic bag and filled the whole chamber.

Where are you located? I bought a gallon of each of the two parts and still have about a quart of each left.

Thanks all. Thanks for the offer Gold; we'll be moving to Grand Marais in a few weeks. Can't wait. I think I'll try replacement parts first.
I'm gonna rivet up a storm!

quote lundojam: "Thanks all. Thanks for the offer Gold; we'll be moving to Grand Marais in a few weeks. Can't wait. I think I'll try replacement parts first.
I'm gonna rivet up a storm!"

I looked at my alumacraft last night... if it were me, I'd leave the vertical panel that rivets on the sides alone and drill out only the top panel rivets, which are pop rivets and replace the foam from the top only. This will keep you away from water issues and allow you to use commonly available aluminum pop rivets.

5-
you got it. I'm not drilling through the hull; not that confident. Going in from the top.