So you are saying get a riveted boat and just get it rhino lined?

Which Jon boat is fully welded besides an alweld?

Don't listen to him. Rhino lining a jon boat is a bad idea. For every person who tells you to do it, 10 more will tell you not to.

It weighs down the boat a lot and makes it handle differently. Don't do it.

Do NOT paint or coat anything aluminum that will see salt water. Aluminum when exposed to salt water and air forms an oxide skin that makes it stronger and protects it from the elements. Without oxygen, such as water getting under a coating or through a scratch in the paint, it doesn't form the oxide but eats at the aluminum the same way it does regular steel. In older in board boats they would encase the aluminum tank in foam. It worked great for a while but the deck would start to leak, the foam would get wet, and bad stuff would happen to the tank in a short amount of time.
Joe

The problem isn't painting the aluminum. It's the quality of paint and prep that is done on the aluminum. Any aluminum that is painted for a consumer is usually allowed to oxidize then properly cleaned and etched before it's primed and painted. The proper painting or coating of a boat is usually more expensive than buying a new boat especially with rivets which will move and allow the sheets to expand and contract. Like the article said, aluminum forms an oxide when exposed to free oxygen. Water trapped under a coating or paint will not provide this. I believe that the green boats you see being sold are electro painted much like powder coating where it's actually bonded to the metal at a molecular level. Most scuba tanks that are painted are steel tanks. The colored ones in aluminum are usually anodized. I have a close friend in Oregon that has a metal finishing company and also builds his own aluminum boats. Not the tiny little john boats but 30'+ pilot houses. He likes his boats to be black. Doing the work himself and getting materials at shop prices it was almost $15k to paint the outside of his last one. It takes the same process as painting planes to do it right though. Paint and plane with different charges so that it bonds and not sticks to the object. Some guy in his back yard with a bucket or spray on of brand X is not the way to do it right. If a boat leaks and you coat just the outside then any water that gets inside the boat will "leak" between the coating and the outside.
Joe