I'm making a boat out of an old aspen tree trunk. Any tips or something. For example I'm not really sure if or how to waterproof it. I already tried it in water and it kinda worked, but the water line was too high (I will fix it by doing more hollowing). I'm set for sail in four days and I need it to work only for a week

>>2933667 (OP)
You water proof it by painting acrylic on it. Plenty of youtube videos doing these dumb things. Just buy a boat.

It's called a dugout canoe, OP, and you can find plenty of info under that name. Usually they're sealed with tar, pitch or pine sap.

>>2933667 (OP)
Lots of videos online, but this one is one of the best.
https://www.youtube.com/watch?v=ueFiy-uxI4Y
Personally I think this sort of thing is usually not worth building because the tree you have to use has to be large to get a large sized dugout. This works for the native Yurok of California because they use something like a quarter of a redwood tree trunk to make a single canoe that can hold a lot of people. A tree like yours is lucky if it can support yourself. Also your wood is cracking at the front so a water bending technique might not be an option. Also looking at wood dictionary it seems aspen isn't normally used for canoes.
https://www.wood-database.com/