There is a lot of misunderstanding here about “glued” PVC. In fact, “glued” PVC is actually solvent-welded, whereas “welded” PVC is heat-welded, and both methods result in a similar fusing of the membrane. That is probably why Saturn does not use the term “glued” and uses the more accurate term “bonded.” Also, “welded” PVC may be more susceptible to damage from folding than “glued” PVC. Furthermore, the four layer bonding construction used by Saturn actually provides more overlay and reinforcement of the seam than the simple overlap of welded construction of welding. This is probably why Aire does not depend on their welded seams to provide an air tight tube and chooses to add an internal air bladder.
For the record, I have an Aire Force XL kayak with welded construction and am considering purchasing a four layer bonded-seam Saturn raft.
The following is from the Vanguard web site:
There are currently two major methods constructing an inflatable boat: welded and glued seams. Glued seams on a PVC boat are fundamentally different than glued seams on a rubber (Hypalon/Neoprene) boat.
Glued (PVC)
Strength/Bond type: Strong -- Chemical/Molecular bond
Cost: Affordable -- Little to no fabric preparation is necessary at the factory.
Durability: Good -- Problems with old PVC boats falling apart have been resolved for over 10 years.
Welded (PVC/Polyurethane)
Strength/Bond type: Strong -- Molecular bond
Cost: Affordable -- Requires well trained workers.
Durability: If temperature, feed rate, and other factors are ideal: Good. -- Welding combined with folding a boat can cause microscopic fracturing of the coating resulting in the boat loosing air over time. Welded seams are not advisable with polyester base fabrics.