Re: variable ballast

[shawl@torchlake.com (Jonathan Shawl)]

Hi,
Again I used the KISS (Keep It Simple Stupid) method on my "homemade" trim
system. It is almost just like your K-boat system but there is no check valve
anywhere and it has a valve you don't have.
It has 3 valves total and a internal steel tank, it hold about 40 lbs of water
total. One valve is used to pressurize the tank, one 1/2" ball valve to vent the
air, and one 1.5" ball valve to admit or vent the water. It works as fast or as
slow as you want it to. I use 2 gauges to compare internal and external water
pressure so I can tell if water will go in or out, and how fast when I open the
water valve. I like my system and wouldn't change it at all.
I can even have fun with it if I want to shake up the passenger. Like this, at
the end of the dive and near the surface I just fill the tank to 125 psi with air
and open the 1.25" valve all the way as fast as I can. This blows a hole in the
water on the left side of the sub. It displaces a lot of water in a hurry! This
has about the same affect as something exploding right next to the sub. I will
include a built in warning now. DON'T TRY THIS STUNT, IT IS DANGEROUS. Ok ok, so
I have a weird sense of humor sometimes. :-)
Jon


VBra676539@aol.com wrote:

> Ray,
>         I had an interesting observation from Dom Liberatore the other day.
> We were talking about the PC-1204 Clelia that HBOI operates.  Dom has 50-60
> dives in it, and hundreds in the JSLs.  I asked how he liked the 12-boat,
> feeling kind of sly because it does a number of things much better than the
> Sea-Links.  He fooled me and immediately responded by complaining about the
> 12's deathly slow trim system.  I hadn't thought about it in years, but it
> made me wonder what the psubbers were using.
>         My K-boat uses a single hard tank, valved top and bottom with a
> compensated low pressure air source Teed in behind a check valve.  Open both
> valves to flood, close when trimmed and then pressurize the tank to 125 psi
> over ambient pressure by opening the VBT air supply valve.  If you need to
> trim, you valve the air off and open the top (vent) valve to relieve air
> pressure and bubble a little water in for additional weight--or merely crack
> the flood (lower) valve and allow the overpressure to expel some water (or
> blow dry if you've a mind).
>         The JSLs use a similar system, only they use air operated valves of
> HBOI design and manufacture.  The adjustable-over-ambient pressure is handled
> via an externally mounted regulator.  The tanks are vertically mounted,
> tubular units, flat ended, and are integral to those enormous main ballast
> tanks.  Vent and fill is very quick.
>         Dom's complaint about the 12-boat was the Perry-style variable trim
> system which is composed of a valve manifold, 2 fiberglas tanks and an
> electrically driven positive displacement pump, all mounted internally.  It
> is pretty quick to take on water, but the vent/fill lines are only1/2"
> stainless, not the 1" aperture air operated valves the JSLs use, and to pump
> out, well, it takes awhile, to be kind about it.  And in 1000 feet of water,
> it takes a LONG while.
>         The beauty to George Kittredge's dirt-simple VBT and the only
> slightly more ornate Johnson Sea-Link variant, is their speed and lack of
> moving (or electrical) parts.  I am wondering what the rest of you
> mad-hatters have used, or are planning to use.
>         And besides, I'm tired of talking about batteries .... for now.
> Regards,
> Vance