um, don't do that - unless you want to gain a ton of weight on the boat - put the boat on a driveway or deck and fill it with water to start and see where it comes out.
Then put it straight up and do the same thing, and do it to the other end.
After it dries completely out, sand and repair your cracks. Also, go get the West System pumps for that resin/hardner to ensure you have the proper ratio. Heat and humidity will effect the cure time and hardness. The longer the mixed resin is in your mixing pot, the quicker it will set up.
I still have my squirt boats from the 1980's - they're irreplaceable. But the more they've sat in the sun, the more brittle they've become, especially those with Kevlar in the layup.
I bet you have either cracked seams, cracked cockpit combing, leaky grab loops, etc. The old Slalom boats were meant to be light, and some folks never put end pours in, or even did inside seams - anything to save weight.