I intend to build pontoons for a houseboat,the design i have chosen are hexagenal 3mm steel, baffled every 1200mm and fabricated in 1200mm sections. To achieve the hex shape i will have steel sheets 1200mm x 1800mm folded with two folds per sheet @ 60 degrees then will weld two sheets together to make the hex making 600mm sided hex, i will then weld these sections together to make 12mt pontoons.My question is this when welding these sections togther what is the best sequence to weld them together. I assume i tack each corner first, then do i weld one side then the opposite side and so on.