A wee bit of 47 y.o. advice here.
This is different. Why, because what works...works, and what doesn't....simply doesn't, and it's all been tried.
Forget safety for a moment. What a hobbyist builds has to be functional or you don't get the opportunity to risk your life just yet. We have seen a number of examples of just this scenario.
The real value of the information available here is in "time, money and effort". Pay close attention, and discount that nagging little voice in your head that is not liking what it heard because it doesn't fit into your plans.
And that, is the biggest mistake I have seen people make.
Joe
>From: Ken F
>Reply-To: personal_submersibles@psubs.org
>To: personal_submersibles@psubs.org
>Subject: Re: [PSUBS-MAILIST] VBT's & The Apology
>Date: Sat, 26 May 2007 01:23:36 -0700 (PDT)
>
>Vance,
>
> Wow, I really had no idea that what I was suggesting was so taboo. You make it sound as though I violated some oceanic statute just by bringing it up. I had tried to stress early on that at 23 I'm a bit young, and I realize that, but maybe if you can calmly inform me of any really horrible no no noooo's then possibly you can just drop me a note or something? Scolding me publicly is hardly a conducive way to promote the free flow of information and subject matter in a board which is not governed by insurance policies nor commercial institutions.
>
> Furthermore... I think that your view of the future of submersible use, especially by private contractors, is archaic. Actually, I might leave the dinosaurs out of it and just leave it at "outdated". I realize that the older crowed here spent alot of time either on the surface, or on the bottom, but never in a capacity where a diver might need to exit the sub at a spot somwehere BETWEEN the surface and the bottom. I'd imagine that I'm a whole new species of human who can find extremely usefull ideas for establishing a protocol of correct procedure and safety for exiting and reentering a sub while in a column of water, and not grounded at the bottom.
> I'm sure there are several possible scenarios for the situation. I like to think "outside the bun". It's a nasty habit that tends to get me promotions. The more informed I am about several ways I can do something, the more contingencies I can come up with when I need to make decisions. I'm not sure that limiting myself with conventional taboos is necessary.
>
>I also like to be safe though.
>
>Ken
>
>
>vbra676539@aol.com wrote:
> We've been through this. no, No, No, NOOOOOOO!!!!! The boat WILL NOT be neutral, or even close to it while a diver is outside. Live boating, as moving the sub while the diver is outside is called, is strictly forbidden by insurance companies, commerical dive procedures and common sense. You build the boat to flood negative in excess of the BOTH diver's weights, as your tender may in fact have to get out to serve as rescue or back-up diver. Mid-water diving??? Sheesh! Come on, guys. Vance
>
>
>-----Original Message-----
>From: ShellyDalg@aol.com
>To: personal_submersibles@psubs.org
>Sent: Fri, 25 May 2007 12:51 am
>Subject: Re: [PSUBS-MAILIST] VBT's
>
> Hi. This is in response to the diver weight compensation question.
> Every dive trip in your sub requires careful measurement of what you bring on-board.
> If the dive plan calls for a diver to exit the sub while at depth, I would think that it would be better to add buoyancy to cover the divers extra weight while on-board, and then dump that buoyancy ( air bubble ) when the diver exits the sub, there-by maintaining neutral buoyancy while the diver is outside.
> When the diver is back on-board, blow the required amount of air back into the trim tank ( a measured amount of water to compensate for exactly how much the diver weighs ) and again maintaining neutral buoyancy.
> A sub with a diver lock-out function would need a bigger trim tank than a sub without that capability.
> Don't forget to calculate how much air the diver displaces with his body, as this will figure into the required additional buoyancy too.
> You don't need a separate pump system, nor would that be desirable, to let a diver exit and re-enter the sub. The lock-out chamber is controlled by air pressure, and any small amount of water that remained within would be easily compensated for by the additional trim tank volume.
> You WILL need some means of dumping the air from the lock-out chamber once the water is blown out and the hatch is closed so the diver is once again at one atmosphere. This needs to be monitored closely so a diver has time to dump the excess nitrogen absorbed by his body tissues and blood. A diver lock-out chamber is really much like a de-compression chamber, but is located inside another chamber ( the sub's pressure hull ) so a compressor to drive out the additional air is required.
> Frank D.
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