My 58-year-old aluminum boat has welded seams, and has never had any cracked welds. The seats and bottom ribs are riveted, and a few of the rib rivets have leaked. I just fill it with water on a dry concrete driveway and see where the leaks drop, mark them with a Sharpie and flip it over and dab some JB Weld over the leaky rivets, and it's good to go for another year. I would prefer a welded seam hull.
But, my boat is probably built of aluminum twice as thick as a current production boat. Pics in this section under My Dad's 1959 12-Foot Boat. IslandJim
I'm an Eighth Day Adventist. On the Eighth Day, God went fishing!