The double hull yachts sized of 520cm,600cm,650cm,700cm, we call Tuna boat. Tuna boats are made of 4mm thick powder coated marine grade aluminum for boat hull and 1100 Dtex pvc fabric or 1.0mm hypalon fabric for inflatable tube. Aluminum hull inflatable boat and Inflatable dinghy for sale TB520 is one kind of yacht tender.