Mark Meadows cleans the brush holders in preparation for the final assembly of the scooters and their new hybrid motors. Thanks go to Mark, Paul Blanchette, Nigel Jones, and Bill Stone who've all put a great deal of work into creating more robust scooter motors. These should make possible much longer missions into O-Tunnel in the coming weeks [photo ©1999 Barbara Anne am Ende].

Jason Mallinson, with the help of Brian Kakuk and others, finished assembling the second dual MK5 rig today. Here Jason prepares to enter Wakulla Spring on a test dive with his partner Rick Stanton. They successfully conducted a 2 hour dive down to the Grand Canyon (finning) and around the basin, practicing rig switches at depth [photo ©1999 Barbara Anne am Ende].

The dual MK5 rebreather rig, shown here with Rick Stanton attached for scale, is fairly large. However, the rig does not stand up higher on their back than a single rig (and indeed is not larger in profile than a standard set of Florida cave diving double tanks), and thus the drag is not increased over the single rigs we have been using. A form fit rear shell is scheduled to arrive on Tuesday which will cover the two vertical (grey) carbon dioxide removal stacks and the central green oxygen cylinder. The maze of black and green cables, brass fittings and connectons are part of the digital gas management system. These will all go under the shell during an actual in-cave mission [photo ©1999 Barbara Anne am Ende].

This photo, taken from the decompression platform shows Rick Stanton underwater as he joins Jason (just out of view) to practice making gas switches in the spring pool in preparation for their upcoming dive down O Tunnel. The dual MK5 has a minimum range of 18 hours at depth and allows for switches between completely independent closed-cycle life support systems in the event of a failure in the primary system. The large yellow cylinders, as with previous missions, carry 90% helium / 10% oxygen bottom mix. Although a very small amount is used for the descent into the cave, its use is negligible on a normal mission. The large size is strictly for use in an emergency to bide time while switching between rebreathers and sorting out a potential problem. The thin pink cylinder carries air for inwater decompression prior to reaching the PTC. The rebreather mixes this in real-time to form a varying Nitrox mix with a typical PPO2 of 1.4 bar [photo ©1999 Barbara Anne am Ende].