truck bed liner on canoe

Anyone ever paint a canoe or kayak with truck bed liner.  I have a buddy that is going to pain his 15 ft canoe with it on the inside. and down to the water line on the outside.

What's the purpose for applying the bedliner? I don't see any good in putting it on the outside of the canoe, and if he's looking to quiet the inside or help for traction of some sort on the inside look into getting hydroturf.

Won't the texture grab weeds and make it harder to paddle? 

Sounds like the perfect application for the almighty flex seal

Why???????

Just going to make it that much heavier.