Mark all leaks after filling boat half full of water off ground. With one person holding flat side of ax on one side of rivet, another person can tap rounded side slightly with hammer or mallet. If still leaks use aluminum melting rods, jb weld, or epoxy. Mark any other leaks with a red marker on next outing on water. If rivets are in bad shape find someone to aluminum weld all leaking rivets or replace all leaking now before repairing. Next, add removeable carpet covered plywood after repairs. Always step on braces on entry/ exit until slats or plywood is added to prevent further leaks. Some boats are made of thin aluminum making leaks occur more often. A good all welded boat is worth its money if a boat launch is nearby.