Hi Landon, I’m sorry to hear you’re having such a frustrating experience! It sounds like your iron might not be hot enough to fully weld the TPU layers together – after they’re welded it should be impossible for the seams to peel apart in the way you described.
After spending so much time on it already, it would be totally understandable if you just wanted to get rid of it, and I’m sure someone would want to buy your nearly complete packraft.
If you decide you want to give it another try though, first I would revisit the “Finding the Right Temperature” section of the Heat Sealing Technique page (and re-watch the video on that page) to make sure your iron is hot enough. Also remember you need to keep pressure on the welds as they cool so the fabric doesn’t wrinkle and lift up. Then I’d do several test welds on scrap fabric, let them cool fully, and pull them apart to make sure the TPU on the two layers of fabric is actually welding into a single layer that can’t be separated without tearing it away from the woven fabric.
When you’re sure that the iron is actually welding the fabric together, I’d go back to the packraft and give all of the tube-to-tube seams and reinforcing strips a once-over with the iron (and as much of the tube-to floor seams as possible through the zipper). If necessary, tube-to-floor seams can be reinforced from the outside with a strip of fabric. You can iron over Aquaseal without causing any issues – just place a piece of parchment paper between it and your iron (thanks to Stefan for this tip).
The above will likely take several hours, so if you decide you want to sell it I’ll try to help facilitate a sale. Cheers!