I think the main reason for this setup are costs and weight. In case of the Tornado I suspect that Marstroms techniek of making the hulls in one go (not in halves) makes integral trampoline tracks by laminating in a carbon tube rather difficult if not impossible.

Personally I have the laminated in carbon tube integral track and due to a summer storm this year my boat was covered by 10 inches of wet sand with a gap below my trampoline. I calculated this to equal a 1000 to 1400 kg laying on my trampoline. My trampoline was fully stretched out and hung between the bulls in a big downward ard. Middle of tramp came some 8 inches below its normal level. It looked awfull and I was sure that I had to buy a new trampoline. More so because the trampoline wouldn't move back to its orginal state after I removed all the sand. It was like it had been 3D molded to this inversed dome shape. Luckily after a week of heat from the sun the trampoline black mesh polymner molecules remember their original stated when they were cast in the factory and the trampoline slowly moved back to its orginal size and flexibility.

Point of the story is however that the side tracks held the loads that were linked to holding some 1000 kg's or more of the ground. The loads on the tracks must have been much higher as a result of the amplifying effect of a tight trampoline. This together with the fact that tracked trampoline systems on the Taipan have withstood the loads of centre sheeting and jib sheeting for 15 years now convinces me that tracked systems can not be regarded weak or less strong by any standard.

This leaves weigth, cost and ease of production as the only possible reasons for one over the other. That and maybe the reason to let air out. However I see trapped air as a benefit as well. High pressure under the trampoline will lift the boat out of the water right ? Something we are all trying to do with canted boards and stuff. Must be a benefit then.

Wouter