Welcome to the board
Regarding the boat...Oh my!
First I would like some questions answered to determine what the next step should be:
Was the tube deflated and filled with water? That strip is just added protection on top of a lap joint, and shouldn't have anything to do with the tubes attachment to the boat.
How is the top of the tube material? Pictures? Looking for any missing material, fading, paint, patches etc.
Can you retake the bottom photo now that the water is drained? Including from the stern. It's hard to tell what that grey thing hanging down is.
Rip that patch off and take a photo to show what is under it. Weird place for a patch, and they used what looks like 3M 5200 which has no place on the tubes.
That is a Hypalon aka Orca material boat, but those scratches on the port side stern are somewhat deep. Is there more similar damage on the tubes, or worse?
Are there other patches on the boat? If so are they put on properly with rounded edges and using a two part glue?
How is the rest of the boats condition?
When you did the repair to the drain plug did you probe the inside of the transom with a sharp object? That is a common leak and most often the transom is soft. This will either require transom replacement, or removing and filling in any damaged areas. The top deck drain and any penetrations like for the outboard should be checked too. A small pointed but not sharp hammer can be used to listen for soft spots, like a ball peen. I use a very hard tipped plastic faced hammer. Transom repairs can be very major, requiring cutting the back of the fiberglass off. (Mine was heavily damaged but I was able to get it dug out, dried out using a hair dryer and heat gun for days. Then it got filled in with biaxial fiberglass and epoxy, starting at the bottom and eventually pouring it from the top. My damage was pretty much down the center around the penetrations, and I am confident in my repair. It took a ton of hours to get it repaired though, but far less than removing the tubes, and cutting the back of the transom off. There is a point the boat should be considered scrap.)
How are the seats, cushions etc on the boat? This kinda tells a story of how much sun it has seen.
Thoughts:
My boat is a 2000 model year, and the Hypalon tubes were in horrible shape topside, with threads showing all over and the rubber completely sun dried, to the point I sanded parts of the top rubber off. I had considered making new tubes, but the cost of material was high. Now I wished I would have used the "old" tubes and patterned new tubes, which is NOT a job for most folks, and even I would have had a challenge setting up an almost 20ft work bench. We covered the tops of the tubes in quality PVC material, and I have no doubt it will hold up, but I am worried about the bottom material failing as yours did. The time needed do such repairs is prohibitive to most folks and I had a friends help. Cost was high too for what I will call a temporary repair, but I expect my boat to last another 7-10 years. Point being you need to decide if repairing the boat at all is worth it, and if it is possible to just fix what's broke, or spend $8K on new tubes.
The seam peeling as yours has done is fairly common from the force of water.
The repair will require new Orca material and a two part glue. My preference is Stabond which can be purchased direct or from NRS.com. NRS is a good go to supplier for raft parts in the USA. They also have great videos and helpful information on their website. They are geared towards white water, but there is no difference from white water tubes and RIB tubes. If anything white water tends to hit more rocks!
The rub rail looks like it was put back on higher than it was originally. That is a sign things have failed already, although rub rail glue failure glue is not uncommon.
To perform the repair it will require removing the back part of the rub rail. A heat gun will be mandatory for such repairs and can be purchased for a reasonable price from Amazon, or Harbor Freight. Get a decent one though with adjustable heat. You will need a quit a few other tools too, but nothing too major.
I can share more tips and tricks as I am sure others can once determined what route to go. Would be good if we did a conglomerate "How To" article on repairing and patching rubber boats that we could point people too in the future. Along with fiberglass repairs and gel coat in another. Sometimes out of 10 videos, only 1 offers decent information, and the rest can mislead people. My wife keeps saying I should start a Youtube channel, but who wants people trying to chase you down, and posting your address online, as theft is always of concern for me. Plus the time needed to video and edit is often more than the job itself.
