Re: [PSUBS-MAILIST] Diver lockout VBT

[vbra676539@aol.com]

Let's think about anchors, here. You'd be carrying the thing with you, correct? So, you winch it to the bottom. The anchor is still attached. Yes? Then you are still neutral. An anchor, by definition, must have either weight or grip. How would that work on a neutral vehicle? And then, of course, your diver leaves. Yes, his volume must be compensated for. And his weight accounted for. But the poor sap inside (the tender) is not going to be wanting to sit in waist deep water waiting for the job to be done. Therefore, he will blow down slightly to expel the extra water. Yes? Otherwise, how would we get to look at the pretty moon pool and the curious fish nosing up into the hatchway looking for tidbits. Unfortunately, this does little to solve your situation. The sub itself is NOT secure at neutral buoyancy. The only boat I know of that was designed this way was the old Roughneck (Beaver IV) and the anchor system was a pain in the behind. And it was NEVER considered for commercial work. Beaver was a developmental product from the 60s which failed to impress anyone who ever laid a hand on it, as even the batteries were custom built. HYCO bought a sister hull and built Pisces IV out of it, and the only thing they used that even LOOKED like the Beaver were the hulls themselves. The rest of it was modernized. Mid-water diving was accomplished in the oil fields by Intersub PC-18s using a big clamp arrangement on the sub's back to hook onto lateral supports on the rigs--then the aft VBT was flooded as per normal (as if on the bottom). The boat was still about 600 pounds negative for lockout ops, even hanging in mid-water. Otherwise, how could you control ascent issues if anything went wrong. Trust me, dragging a friend toward the deadly daylight by his air hose is not the way to spend a happy Sunday afternoon. Vance


-----Original Message-----
From: Sean T. Stevenson

To: personal_submersibles@psubs.org
Sent: Fri, 25 May 2007 7:35 pm
Subject: Re: [PSUBS-MAILIST] Diver lockout VBT

With regard to Vance's comment about insurance for commercial lockout ops
prohibiting live boating a locked out diver, is it sufficient to anchor a
neutral trimmed boat over the bottom, or is it necessary to have a skid
arrangement to touchdown and flood negative?






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