"Abaft the tower in the S1 01 is a 550 litre (121 gallon) internal ballast tank,"
Regards,
Brent Hartwig
From: "Brent Hartwig" <brenthartwig@hotmail.com>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] VBT's
Date: Fri, 25 May 2007 18:47:40 -0700
************************************************************************ ************************************************************************ ************************************************************************ The personal submersibles mailing list complies with the US Federal CAN-SPAM Act of 2003. Your email address appears in our database because either you, or someone you know, requested you receive messages from our organization. If you want to be removed from this mailing list simply click on the link below or send a blank email message to: removeme-personal_submersibles@psubs.org Removal of your email address from this mailing list occurs by an automated process and should be complete within five minutes of our server receiving your request. PSUBS.ORG PO Box 53 Weare, NH 03281 603-529-1100 ************************************************************************ ************************************************************************ ************************************************************************Paul Moorhouses first sub the S1 01 has a fairly large VBT inside the sub, just behind the pilots seat. I would guess that it is the MBT for the sub, and that it is mostly controled with a high pressure pump and solinoid valves. I havn't seen much in the way of detailed design data on this sub so I can only guess for the moment. This tank is made partly out of flat sides, so I don't know if you could call it a hard ballest tank even thought it is inside the main pressure hull. So if water is added to the tank, I would expect the air in the tank that the water is displacing to not compress, but rather vent into the main compartment incressing it's pressure some what.
There might be soft ballest tanks in the bow and stern of the S1 01 as well. This design is quite stream lined, opting for length rather then girth by not adding saddle tanks.
http://www.frappr.com/?a=viewphoto&id=2384531&pid=4157781
Regards,
Brent Hartwig
From: Rob Bryan <Sundiver2000@earthlink.net>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] VBT's
Date: Fri, 25 May 2007 16:36:44 -0600
>I'd certainly agree. A surge could roll the boat and burp air
>midwater or come back down on the diver on the bottom. It needs to
>be very stable and heavy. Put bubblers in the feet if you're worried
>about getting stuck. Frank's point about it being a decompression
>chamber is a good one. Decompression needs to be managed from
>outside the lock chamber or at least over ridable. A small
>compressor would be necessary to depressurize the lock (or a trip to
>the surface along the decompression schedule). If the sub is so
>small (displacement wise) that this is an issue, I'd say locking out
>would be a very high risk operation.
>Interesting topic.
>Rob B
>
>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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>
>
>
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