Quack Addict

GM has not "fixed" the problem because it isn't a big warranty issue - so it is not a problem - to them anyway. Genuinely "fixing" the problem would require expenditures on their end: engineering & design, validation costs, material changes (say they upgraded some carbon steel components to more expensive stainless), etc. Then, by fixing the issue, customers that own the old parts would bitch saying GM knew there was an issue and changed something to fix it, so they'd want no cost replacement after their warranty expired. That's one reason why many new parts are designed to not directly interchange with the old parts they replace. GM's warranty liability becomes your financial responsibility when the warranty expires. MANY components are engineered & designed to outlast the warranty, not to withstand true vehicle life in the field.

Thanks, I've been on here for a while just haven't posted anything. I've caught some flack for this on other forums but I have never used marine plywood for any transom or floor I've done. So far as I know, every boat I've ever worked on is still going strong and some of the boats have 15 years on them now. YMMV. 5/8" should be plenty. It probably doesn't make a difference as I doubt anyone would ever notice but the governing USCG Reg for foam (# 33 CFR 183.114) is 2 lbs/ft^3. My experience with A-B foam is you never get the advertised yield, i.e. if the kit says you should get 18 ft^3 when expanded, you end up with a less than that even when pouring it in 90*F summer heat. Yield is somewhat dependent on ambient temperature, yield is higher when it is warm outside. An unheated garage in winter isn't a good idea for doing glass work or pouring A-B foam. I have salvaged good chunks of the old foam in boat hulls (foam that isn't discolored or showing evidence of moisture) and thrown those chunks into the cavities to be filled before pouring fresh foam in. Those foam blocks get encapsulated with new foam and save a little bit of $. Not sure how you plan to look for leaking rivets but the method I've always used is to take the round end of a 12oz ball peen hammer and tap ALL the rivets with it. Pay attention to the sound. This method will show you all the leakers plus the ones that are getting ready to let go. Use the right rivets for the repair. Regular hardware store rivets are not proper to use on an alumium boat hull. Personally, I would rip out the old floor, transom and flotation foam first, then inspect & replace all questionable rivets. That way you can get at most of the rivets from both sides if needed. A-B foam kicks (starts to expand) pretty fast and you want to make sure you have it mixed well before it starts to go. If you plan to mix it with a paint stick or whatever, you won't get it mixed in time. As a mixer, I took a 12" long x 3/8" carriage bolt i had laying around and drilled a couple holes through the rounded end about 2 or 3" apart. Then I poked a chunk of wire from a coat hanger through the holes and bent it into a square shape and brazed the wire in place so it won't come out. I chuck that up in my drill and use that as a mixing head. It works better than most commercial mixers I have seen because you can clean it off with a utility knife after the foam hardens - most of the mixers you buy have plastic parts on them that aren't so knife friendly. When I know I have a floor job coming up, I have all my friends and family start saving empty gallon milk and water jugs for me. Ask them rinse the milk jugs out first and tell them you don't need the cap (this lets them dry out inside and not ferment). Take a utility knife and cut the top off the jugs at about a 45* angle and you have a perfect & free disposable mixing container. I also use these for mixing resin when doing glass work. Foam and floor jobs I have done, I have needed >20 jugs... If you go the route of using polyester resin, avoid getting the peroxide hardener on your bare skin or clothing... chances are you will only do it once, then you'll understand what I'm talking about Make sure you get the FRESHEST poly resin you can find. The crap that's been sitting on the shelf at West Marine or Home Depot with an 1/8" of dust on the lid isn't any good. Poly resin has a shelf life. The fresher the better. Old resin will still react but it doesn't flow as well as fresh resin, you could also end up with issues bonding to the wood substrate (it won't soak into the wood as well), might not cure 100%, may not cross-link properly with bottom layers or top coats, etc.

I've done a bunch of boat floors and hull restorations for customers when I worked for a marina and more recently my personal boats. Never did a floor in a boat with an aluminum hull though. 99% of the work I've done was using polyester resin, different types of fiberglass (depending on the application) and gelcoat. Working with epoxy has its +'s and -'s. Given the option, I'll use poly resin most of the time. My current boat (8' beam) has several layers of 24oz woven roving laid at different angles lock it together. I buy it in 50" widths. The top layer of roving has 1 seam right down the middle of the floor but the visible seam is minimal due to the 7' long fuel tank access panel I put in that stretches most of the span between the engine hatch and steps down to the cabin. I also filled the seam with a fiberglass reinforced automotive body filler so it's not readily apparent. To top coat it all, I used thickened gelcoat and applied it with a 3/8" nap paint roller like you'd paint your living room with. That left a rough finish that would draw blood if you rubbed bare skin against it but after a couple days of walking on it, the texture wore down to a nice non-skid surface. 3 years in and it's still in great shape. The only complaint I have about the gelcoat surface in my boat is that it's a PIA to keep clean. It gunks up and turns dark toward the end of the season but cleans up fairly easily with a bristle brush and some soapy water. At some point I may prep the floor and paint over the gelcoat with a durable finish that won't discolor as easily but that's not a priority. You need to be careful with the A-B flotation foam. I fill compartments before the floor plywood goes on, then shave off the high spots if needed and top off any low spots with a subsequent pour. If you drill holes in hollow cavities and over-fill the compartment by pouring the A-B through the hole, it will expand and blow out the seams in your floor or even cause the floor to bow upward. I have seen some boats come from the factory like this. Guys on another site ripped me up over shaving off the top of the foam like this because it opens the cells up to water intrusion. If the open cells bother you that much, brush, spray or roll on a layer of poly resin before you put the plywood down. I have a bunch of in-process pictures of different floor jobs I've done but I'm not going to post them here. I can email you a pdf if you want along with the sources I purchase my glass, resin and A-B foam through. Regardless of whether you use poly resin or epoxy, you will need to purchase some fiberglass rollers to wet out the glass. A proper glass job uses as little resin as possible - the strength comes from the glass not the 'glue' used to hold it together. For sealing the floor to the aluminum hull, I don't think you want to wrap the glass up the sides of your hull. I'd be willing to bet the glass will peel away from the aluminum in a year or two due to a variety of reasons. I would recommend leaving a gap between the floor plywood and hull, then wrap the glass down around the end of the wood. Fill the void between the edge of the floor and boat hull with an elastic filler material. I'd use a polyurethane adhesive similar to 3M-5200 to fill the gap. The stuff I use has pretty much the same specs and performance as 3M-5200 but about 1/4 the cost.