Dam man,

Theres only one good way to tint the windshields and thats to take them off the boat and take them out of the frame. I assume he treated it like a car window and cut the tape from the outside of the window and tried to lay it inside, but realizing the seals on the windows arnt the exact same size from outside to inside.

They used a black marker on the couple edges it wasnt exactly even on. Not the best idea but you cant see it unless you know where to look.

Glad hes standing up and wants to fix it.

best way to get window tint off is spray it with water, tape a plastic bag over it and let it sit outside where its warm, the humidity will release the glue and you you can peel it right off.