So I now have a few different areas of the floor that have been re-attached to the underlaying foam by using 3M 5200 or Gorilla Glue. Please understand the Hunter 170 is a plastic shell construction for those who do not know. So between some very detailed and wonderful converstations with Dave, some comments from others, and my previous experience from car restoration I came up with ways to do the repairs to the Hunter plastic (Luran S) shelled boats. First off you have to always bare in mind that the Luran S just will not adhere well to anything except that special epoxy. That being said some really sticky stuff over a large area and you have a lot more holding power. The problem that needs to be fixed is getting the plastic shell to be stuck to the foam underneath. The glue can not have any real solvents or cure at a high temp as that will melt the foam. I believe that foam comes apart from the plastic because nothing wants to stick to the plastic well. It is just too smooth so there is nothing for the glue to grab. So you have to take a moment to imagine the complex shape of the deck side. Then think about if you get some heating and cooling expanding and contracting the plastic. Plus you have to think the plastic may shink a bit over time (my guess). The results are the cracks and the plastic separating from the foam. This separated stuff is annoying. It can make an area spongy and likely weaker (it is a pretty strong boat). My 170 most of the floor had separated from the foam. It was like a bounce house. Some areas closer to the center bump felt like there was wide separation and the foam seemed lower. I need to add my location. I am in southern NJ near Atlantic City. It is getting colder and the temps are (as of writing) kind of at the bottom edge of the of safe for the 2 glues I am using. I am kind of trying to rush a bit as I want to get the hardware back on so I can move the boat off the trailer to work on the trailer while it is cold. So let me start with Gorilla Glue. Dave recommended that as a way to glue the plastic to the foam. I did not get more details so my idea was to inject the Gorilla Glue using new empty caulking tubes. I drilled the holes like 3-4" apart and made sure I got plenty of glue in there. Do not do it that way!!! I put a board and some weights on top and the glue came out and made a mess. Luckly the glue really is easy to peel off the plastic. You just get a razor blade under it and it comes up. Of course this makes me curious if long term it holds well. Dave assures me they hold up long term. So I learned to use duct tape on my drill holes to keep the stuff in. The area was also not perfectly down. I did not do a very good job. Next I tried the 5200. You need a good quality caulking gun and you will need to duct tape it in the gun. This worked well but took over a week to cure. I changed my weights to a couple of 1" thick iron and a bunch of dumbells I have. I squished a bunch of 5200 out of the one uncovered hole. It did a great job and made a very solid area. I retried Dave's method with the Gorilla Glue. I used air to move the glue around. Put weights on it. The temp was in the low 60's and to be honest I did not feel I got good flow out. I went back to using the 5200 (I had another tube why let it go to waste). So my second attempt with the 5200 I put some water in (very small amount) and blew it in with air. 5200 needs moisture to cure. It has gotten dry here with the winter approaching. I widened the hole distance to like 5" and worked the 5200 in some holding the hole closed with my finger while I pressed and let the 5200 flow. Put duct tape over the hole then weighted it down with my pile of plates and weight. This time it cured faster in just under a week. The area is very very solid. EDIT- I forgot to put an important detail in with 5200. I drill a 1/4" hole thru the plastic. The tip of the 5200 has to be cut such that it does not stick past the Luran on the other side. If it sticks too far thru the foam will block the 5200. I also recommend a good quality ratchet caulk gun. I found that you need to keep the tube in the hole and allow time for the glue to spread. I also work the area by pressing with my hands. The key is to find the edge where you do not here the cracking noise from the plastic pulling away from the foam. The duct tape limits the 5200 from coming back out the hole. Weight on the area should continue spreading the glue. I thought about the Gorilla glue and felt it was too cold to flow easy. So I tried an experiment. I got my hot plate and special garage pot with some water in it. I got the glue up to 80 degrees and found it flowed MUCH better. I also had a long wonderful talk with Dave. There I learned he would put the glue in a hole and blow it to the other hole about a foot away. So I brought my pot out to the back garage and got the glue toasty warm (around 80) and tried it. This worked very well. I put in a bunch of glue using a small container then blew it around. I dumped a bunch of glue in and 3 days later when I had time I took the plates and weights off and a nice solid area. So today the temps were in the 50's. I am out of Gorilla glue and have a tube of 5200. I refined my 5200 techniques. You can get close to 5" of movement of the 5200. When you start the loose areas will make the ripping noise when you press and release. So I would inject the 5200. Keeping my finger over the hole I would work the area listening for when that ripping noise would go away and I knew where the glue had moved. Plus I figure the plate and weights would move it even farther over time. So my summary. I am partial to the 5200 glue. I feel it is likely a better glue because as best I can figure it has a better stick value to the Luran. It does not expand and it can move some as it is rubbery. It is slow and relatively expensive. In reality either solution will work so long as you are aware of temp issues. The Gorilla glue worked nice once I got it up to temps. I recommend getting a smaller bottle for injecting and a really large bottle to refil. I believe in very warm weather the Gorilla glue will flow better for areas that are tight. For areas where better adhesion might be required you are better off with the 5200. Keep in mind my 170 seems to be on lighter end of problems. Some seem to have more problems. If you need to do a full floor area then at least 2 large bottles of Gorilla glue or 5 tubes of 5200. Home Depot has the best price on 5200 at $17 or so.