[PSUBS-MAILIST] Deep Worker 2000 Ballast system
Phil Nuytten
phil at philnuytten.com
Mon Jan 6 23:29:51 EST 2014
Hi, Guys!
Happy New Year y’all
Re: Seat VBT: The system was one we (Nuytco) used in the earliest DeepWorker model subs – starting around ‘97. The seats were black, roto-cast plastic designed for use on/in snowmobiles, home-built race cars, dune buggies and the like – and they were hollow. We came up with the idea of using them as a VBT that could be very precisely trimmed immediately pre-dive and could be easily changed (made heavier or lighter) during the dive. The seat was drilled and tapped for an inlet and outlet line. The water inlet line/hose had a needle valve on the inside of the hull at a convenient spot for the pilot to reach. The outlet line/hose led to a simple, manually-operated hydraulic hand pump and from there to a second on/off valve in front of a non-return valve plumbed through a hull penetrator. To use, the DW was trimmed to be buoyant with the seat empty. while the pilot was floating on the surface and the load line cast off, he opened the inlet valve to allow water into the seat until the dome went under and then the inlet valve was then shut off. This made the hull slightly negative and it would sink slowly, or faster with additional down thrusting. This, for pilots who like to dive a bit heavy. To lighten up, the outlet valve is opened and the water pumped out until the sub became buoyant – just a few strokes, usually. We did try using a heavy duty plastic bag full of fresh water attached to the inlet side to avoid the plankton and assorted little critters when diving in sea water – but we wound up just flushing the seat tank with fresh, soapy water after an ocean dive and that worked fine. All and all, a pretty neat systems except for a few downsides: Ambient water is pretty cold at depth and chills the butt and back – and, you have to studiously remember to shut the inlet valve, particularly at any appreciable depth, because even with a needle valve the water comes in fast. We had a hole in the top of the seat as an over-flow and sometimes got sprayed by the overflow if something distracted you while allowing water in, and a few other minor things. At the time we had this system in place, we were training a bunch ( (40 – 50) scientists as DW pilots over a two year period – the experienced pilots had no problem with the seat VBT but we figured it was just too many things going on for new trainees, and so reverted to a conventional nylon box with holes in the bottom as the VBT, and that’s what we use today. Speaking of which, we brought a couple of DW’s back from a series of science dives in California, a month or so ago – after a few days in the shop one the DWs developed an extreme case of ‘body odor’ - turned out to be a squid decomposing in the VBT!
Finally, colored water ?? We don’t have any colored water in any of our sub models . . well, that’s not quite true, I guess. We do have our handy-dandy, always reliable MRE’s! Yup, yet another acronym – in this case, short for ‘MISSION RANGE EXTENDERS’ – a wide mouth, screw-top plastic bottle that holds about a quart or a little more. We sometimes use two, one full of, say, apple juice and the other one empty. The idea is to pass the full one through you to the empty MRE – and make sure you don’t get mixed up!
Phil
From: Alan James
Sent: Sunday, January 12, 2014 5:41 PM
To: Personal Submersibles General Discussion
Subject: Re: [PSUBS-MAILIST] Deep Worker 2000 Ballast system
Thanks Vance,
I found this description of their system, but not sure if its correct or what
the "colored water" is all about.
DeepWorker uses soft ballast together with another ballast
system known as “hard” ballast. In the hard ballast system,
colored water is contained within an enclosed small
bladder outside the sub. After the pilot dumps all the air
from the soft ballast tank in order to lower the sub below
the surface, the sub remains slightly buoyant. To sink, the
pilot opens a valve to allow a small amount of the colored
water into the sub, which adds weight. The water begins
to fill a tank in the pilot’s seat, and the sub descends.
When the sub is neutrally buoyant (neither sinking nor
rising), the pilot shuts off the valve.
Alan
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From: "vbra676539 at aol.com" <vbra676539 at aol.com>
To: personal_submersibles at psubs.org
Sent: Monday, January 13, 2014 1:32 PM
Subject: Re: [PSUBS-MAILIST] G.L. rules Arrangement for Diving/Ballasting, Control/Compensating & Trimming
They did at one time use a snowmobile seat/gas tank combo to serve both purposes. I think that has gone by the wayside in favor of a small tank under the hull to get the acrylic dome high enough for the pilot to see and maneuver when on the surface. Perhaps it's an optional thing. I'm not sure. They've built a couple of dozen subs by now with the Russian DW-3000s, and there are probably some evolutionary differences between the early models and the later ones. I do think the seat deal was ingenious, and could well serve along with a hand pump as an upgrade for a new build or even a re-build K-sub in lieu of George's heavy trim tank. Having said that, maybe the hand pump is too slow or something. I have no direct experience with them. We'll just have to ask Phil for clarification when he gets time.
Vance
-----Original Message-----
From: Alan James <alanlindsayjames at yahoo.com>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Sent: Sun, Jan 12, 2014 6:17 pm
Subject: Re: [PSUBS-MAILIST] G.L. rules Arrangement for Diving/Ballasting, Control/Compensating & Trimming
Vance,
I thought I'd heard that the Deep Workers had a plastic compensating tank under the
seat.
Alan
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From: "vbra676539 at aol.com" <vbra676539 at aol.com>
To: personal_submersibles at psubs.org
Sent: Monday, January 13, 2014 4:11 AM
Subject: Re: [PSUBS-MAILIST] G.L. rules Arrangement for Diving/Ballasting, Control/Compensating & Trimming
Hank and all,
VBTs are nice if you have the room and the need. All those dives with the Nektons prove you can get along without. And in shallow water, we usually ran the Perry boats a little heavy and then hung on a small bubble in the MBTs. Aquarius has a third MBT (soft tank), a small one up forward, that they use to tweak for neutral after diving negative. Not hard tanks. It definitely works okay. The K-boats have VBTs, but George Kittredge came from the twenty-five hundred tons displacement school of thought.
For us, it's pretty easy just to adjust a little as we go along. Mind you, my 350 has a VBT and I'm keeping it. We did a lot of mid-water work with the JSLs, and the pilots could trim 14-tons dead nuts neutral and then just forget about it. Just so you know, the JSL variable tanks and control systems, et al, probably weigh a thousand pounds in air. Fiberglas tanks and pumps and all the rest in a Perry--probably three-hundred or thereabouts.
On the little-bitty side, the Deepworkers have a simple external tank for surface work, which could certainly be used for variable ballast, but mostly aren't. Keep in mind, that is their ONLY ballast system aside from pre-dive adjustments with lead. Regardless, and aside from the general complexity, VBT systems impose a pretty hefty weight penalty on (in our case) very lightweight boats. Just something to think about.
Vance
-----Original Message-----
From: hank pronk <hanker_20032000 at yahoo.ca>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Sent: Sun, Jan 12, 2014 9:39 am
Subject: Re: [PSUBS-MAILIST] G.L. rules Arrangement for Diving/Ballasting, Control/Compensating & Trimming
Jim, Joe,
When I test Gamma next month or when the weather improves, I intend to use a ballast bag that holds 350 lbs of water. I will place it where the passenger is normally. There is the benefit of less draft on launch and less weight to haul for 12 hr of driving. I will not need to screw with weights in and out. I bought the ballast bags for other reasons and think they might be the answer. Gamma was built with a trim tank that was removed, so I want to put some dives on it before I decide if I need it. Like Vance says firmly, you don't need a vbt. In an effort to keep it simple, I will try it without.
Hank
On Sunday, January 12, 2014 7:27:35 AM, "jimtoddpsub at aol.com" <jimtoddpsub at aol.com> wrote:
Hi Joe,
I tried hard to come up with a VBT system to greatly reduce the need to load or unload lead to adjust or compensate for passenger/no-passenger and the variability in the weight of the pilot or passenger. That would have meant adding 25-30 gallons of VBT capacity to whatever VBT capacity was already planned. It also meant that VBT would have to be located at the same position fore/aft as the passenger. Picture in your mind the size of a 30-gallon drum. Whether the VBT was internal or external it was very apparent that it just wasn't workable.
Adding/subtracting lead externally isn't so hard when the sub is on the trailer, but it's difficult when the sub is in the water. In the end the simplest, most convenient system came right back to +/- lead directly under the pilot's and passenger's seats. The only practical alternative I've seen so far for a very small sub is Alec's arrangement for adding or subtracting trawler floats to adjust buoyancy.
I have two external VBTs - one fore, one aft, so they can be used for trim as well as overall buoyancy. The capacity of each is not yet determined. The forward one can be used to compensate for the addition of equipment up to a point.
Best regards,
Jim
-----Original Message-----
From: Joe Perkel <josephperkel at yahoo.com>
To: personal_submersibles <personal_submersibles at psubs.org>
Sent: Sun, Jan 12, 2014 6:18 am
Subject: Re: [PSUBS-MAILIST] G.L. rules Arrangement for Diving/Ballasting, Control/Compensating & Trimming
Alan,
I've been giving this issue of fine buoyancy control some thought lately. In the literature is there any mention of a rule of thumb volume to vehicle ratio for the capacity?
On a K-350, the difference between diving solo or with a passenger could be as much as 200 lbs (100 kg). I would think that it would be convenient and useful to be able to compensate for this without having to manually transfer solid ballast (lead). The standard VBT volume is too small to be able to do so.
Joe
Sent from Yahoo Mail for iPad
From: Alan <alanlindsayjames at yahoo.com>;
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>;
Subject: Re: [PSUBS-MAILIST] G.L. rules Arrangement for Diving/Ballasting, Control/Compensating & Trimming
Sent: Sun, Jan 12, 2014 9:20:37 AM
Hi jim,
here's a G.L. quote. "Normally compensating tanks are to be provided for a fine
adjustment of the wanted depth and for balancing of changes of buoyancy
because of consumption of provisions & supplies during the underwater voyage,
changes of the density of seawater, taking on or taking off of payloads as well
as effects of buoyancy/loss of buoyancy."
This section covers hard & soft tanks, internal & external, & calls them all
compensating tanks.
Alan
Sent from my iPad
On 12/01/2014, at 9:59 am, jimtoddpsub at aol.com wrote:
Hi Alan,
Thanks for posting that. What all does "compensating tanks" refer to?
Best regards,
Jim
-----Original Message-----
From: Alan James <alanlindsayjames at yahoo.com>
To: psubs.org <personal_submersibles at psubs.org>
Sent: Fri, Jan 10, 2014 5:37 pm
Subject: [PSUBS-MAILIST] G.L. rules Arrangement for Diving/Ballasting, Control/Compensating & Trimming
Hi all,
This is my G.L. summary of Diving/Ballasting, Control/Compensating & Trimming.
It builds a little on a previous section "Stability & buoyancy".
All the ballasting controls & systems have to work under previously specified heel & trim requirements. Including when one main ballast tank is damaged.
It has to be possible to check these systems prior to diving.
The sub must be able to surface after the failure of a compensating tank.
Flooding & bilge openings are to be protected with grids, filters or strum boxes to stop the entrance of foreign matter.
All the operating units for controlling positive & negative buoyancy are to be grouped together & clearly marked on the control consul. This control consul is to have indicating instruments showing depth & trim.
Separate shut off valves are required for each ballast tank.
The vent valves are to be designed in such a way as to prevent unintentional opening.
Where diving tanks have flooding holes without means of closure, double shut-off
valves "May" be stipulated for the vent pipe.
The blowing line for each tank has to have a separate shut off.
Blowing the tanks cannot cause an excessive over-pressure.
Where the diving tanks are pumped out there needs to be a closure valve & back up bilge pump. No excess under-pressure can be caused.
Compensating tanks are to be designed big enough for all the changes in
buoyancy plus 10%
Compensating tanks need contents gauges to give continuous readings.
The compensating tank vent pipes need to be wide enough for maximum
inflow / outflow and designed so that water can't flow from them unnoticed in to the hull.
The volume of the trimming tanks is designed in such a way that all planned trimming situations can be adjusted by combined filling & emptying of the various tanks.
Alan
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