For those of you who think the Dacor Nautilus CVS would not work with a full wetsuit, I'd like you to consider something. The wet suit looses almost all its buoyancy at about 33 feet in fresh water. In salt water there may still be a bit of buoyancy, but not much. I learned this lesson by taking my weight belt off and tying it to a butterfly knot loop in the boat's anchor line in the 1980s in Clear Lake, Oregon. I was using about 20 pounds of weight at that time, and when I took the weight belt off, I was completely weightless. I could swim down further, to about 65 feet, without any change in my buoyancy. I swam back up to the weight belt at 33 feet, put it back on and went to the surface. I regained that buoyancy as I ascended. I made a series of dives for the University of Oregon's Department of Exercise Physiology in Clear Lake in the 1960s while home on leave from the military, and did not use a weight belt or a BC at a depth of 66 feet (BCs weren't available then):
Now, if instead I went down with that 20 pounds, and added air to a BC, I again would be weightless with about 1/3 of a cubic foot of air in my BC at 33 feet. If I went down to 66 feet, that buoyancy would decrease with the increasing pressure. If at 33 feet that 1/3 cubic foot of air represented 1/2 of the volume at the surface, it would have been 2/3 of a cubic foot at the surface (twice the volume as at 33 feet). So that would be about 0.66 cubic feet of air at the surface. At 66 feet it is 1/3 of its original volume, or 0.33 x 0.66 cubic foot, or 0.22 cubic foot of air. If one cubic foot of air is 62.4 pounds of buoyancy (64 pounds per cubic foot in sea water), then 62.4 pounds x 0.22 = 13.6 pounds of buoyancy. I have to add about six pounds of buoyancy to my BC. I'd still have to add if I went down to 99 feet too, not because of the loss of wet suit buoyancy, but because I was using air to compensate in a soft BC.
The Dacor Nautilus CVS doesn't have that problem, and once the trim is set at 33 feet, it can be ignored with further depth changes. I have two of these units and have dived them. They are very nice BCs. They do not leak from the regulator (it takes about 12 inches to activate the regulator, a pressure differential of 0.445 pisg). The regulator does not free flow because it is feeding the air into the CVS, and not open to the water outside. This is the same principal Cousteau used to pressurize his camera housings in the 1950s (see
The Silent World, the first photo after page 114, a black and white photo of Cousteau with his camera housing). The Dacor Nautilus is listed in the Dive Dacor 1977 Retail Price List as $199. The four pound lead weight was $8, a weight tract filler at $2, and a carrying bag at $32. I have a copy of the Nautilus Constant Volume System Instructor Manual, and it contains parts diagrams which I'll copy in the next few days. The system was well thought out, and does work. In my opinion, they did themselves a disfavor by picturing it with a shorty wet suit; it is best with the full Farmer John wet suit.
SeaRat