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Hi Jim,
You got the basics covered.
I have a battery voltage meter but it's not really
that helpful as I have it. First off, I have only one and have to select
between battery banks. If you have room install a monitor for each
bank. Mine is placed far from view. Not good. Put it where you
can see is all the time.
I bought a cheep digital multi meter from
Harbor Freight. It was about three dollars and works well. It reads
to two decimal places. I installed the entire meter as it was bought in a
box with cutouts to power it up. That way if I need a multi meter while in
the sub, I simply open the box remove the two leads and remove the
meter and use it.
Better would be to purchase some kind of battery
monitor where it displays with LED's of something, your remaining battery life.
The voltage reading are all over the map depending on current draw and on and
off time. The actual battery voltage is always fluxuating unless it sits
for a whole and settles down. I'm guessing those battery monitors take
averages over time to give a more reliable reading of power levels.
What kind of breathing air are you talking
about? You don't want to be releasing breathing air in the hull as your
diving.
As Emile said, maybe O2 and CO2
monitor. As far as internal air pressure, that changes depending on
the surface air temp before you closed the hatch and the water temp your
diving in. When diving in cold water on a hot summer day I
always have a negative pressure when I resurface. Sometimes I have to open
the breathing tube to increase the internal pressure to make it easier
to open the hatch. Maybe on long dives the internal pressure
would help with air analysis.
A clock is nice and a I find a timer a
must. I plan my dives for a set time and want to return to the surface as
planned. Wives can get panicky fast when your late for a rendezvous on the
surface. (Maybe because I'm not heavily insured)
The inclinometer Emile mentioned is helpful
also. I have one for fore and aft pitch but see no need for one to monitor
role.
Maybe a gauge to monitor your HP air for blowing
ballast. I don't have one because I have a regulator directly on the SCUBA
tank I use. I do carry two tanks and always have one full to switch to
when I'm low.
If your using a fish finder for monitoring the
bottom or what ever, maybe you could incorporate it in your panel. I find
it really helpful to see the bottom coming as I'm descending. Especially
in murky water. It also has water temp on it's readout.
That's about all I got Jim.
Dan H.
----- Original Message -----
Sent: Sunday, March 23, 2008 9:02
AM
Subject: Re: [PSUBS-MAILIST] MBT air
lock
Hi Dan,
I have some experience with gyrocompass and plan
on having one in my sub. If they are in good shape there is VERY little noise.
Even with engine off in my plane, you could just barely hear it. If there is
significant noise the bearings are getting loose and the unit needs
rebuilding. When the bearings get loose and or worn the unit will tend to
precess more quickly and neet to be reset more frequently.
I have a question for you and/or anyone else with
experience in subs. I am trying to keep my sub as simple and basic as possible
and am working on the design of an instrument panel. I have listed below what
I feel is the minimum necessary requirements in my situation.
1. High quality voltmeter with toggle to check
both banks
2. External pressure gauge
3. VBT pressure gauge
4. GyroCompass
5. Air Pressure Gauge for breathing air - one for
each bank
If anyone has suggestions for things that are
needed or should be considered please let me know.
Thanks in advance.
Best Regards,
Jim K
----- Original Message -----
Sent: Saturday, March 22, 2008 6:39
PM
Subject: Re: [PSUBS-MAILIST] MBT air
lock
Yep, Vance, Still plenty of ice.
In some part of the lakes when there is
current, there's the start of open water.
I had so many things I wanted to do on my sub
this winter but didn't have time for many of them. I've been pretty
busy in my shop. The only thing I did was, I added a gauge to read the
VBT pressure. Also a friend is giving me a aviation gyro compass
that I'll be installing soon, but that's about all I'll get to this
year. The arm will have to wait for next winter. I'm thinking
the noise of the gyro compass will be a nuisance but at least I should be
able to tell direction.
How's your boat coming? Will she get wet
this summer?
Regards,
Dan H.
----- Original Message -----
Sent: Friday, March 21, 2008 8:42
PM
Subject: Re: [PSUBS-MAILIST] MBT air
lock
Dan, Of course, you'll have to break some ice to dive
either way, or has spring sprung up your way?
Vance
-----Original Message-----
From: Dan. H. <jumachine@comcast.net>
To:
personal_submersibles@psubs.org
Sent:
Thu, 20 Mar 2008 8:26 am
Subject: Re: [PSUBS-MAILIST] MBT air
lock
Vance,
Ok I stand corrected. MOST times the
MBT are totally flooded when diving.
On a K sub, I don't see the advantage of a
MBT bubble over a bit less water in the VBT. Actually I think my VBT
vents faster then my MBT. If I want to get heavy It's easier to let
a little water in the MBT.
With the slow venting of the K-subs MBT I
think you could get into trouble diving with a bubble in them. If
you started to ascend, I'm not sure if you could release air quick enough
to over come the expansion before you popped up on top.
I don't know if it's the accepted way or not,
but I usually totally vent the MBT's, flood the VBT to neutral, dive with
the thrusters, then fine tune the MBT near the bottom if I want to be
heavier or lighter. Neutral is easier to control but I try to keep
it a slight bit positive in case I "fall a sleep." I'd rather be
found skimming the surface rather then be searched for on the
bottom.
I agree, the K sub VBT's are to slow to
vent. Even in calm water it's tricky to vent equally between the
forward and aft tank to keep an even keel and it takes a long
time.
Still diving without a MBT bubble,
;-)
Dan H.
----- Original Message -----
Sent: Wednesday, March 19, 2008
7:52 PM
Subject: Re: [PSUBS-MAILIST] MBT
air lock
Hey guys,
Not to rain on anyone's parade, but it
was, in fact, perfectly normal in the oilfield subs to trim a little
heavy and "ride the bubble" meaning a shot of air in the MBTs to
maneuver with. It's handy if you are operating near the bottom, and very
quick, assuming a fairly stable depth. That way, you can goof around
down there to your heart's content, and vent quick to settle onto the
bottom if and/or when you need to. Neutral buoyancy via small trim
systems is a fine thing, but slow and finicky to do (except in the JSLs
which have almost as much VBT as most boats have MBT).
Don't sell
yourself short by saying that there's only one way to do things, as
there are, in fact, a whole pile of variations out there, and they're
like spare ammunition for your personal defense firearm--mighty handy to
have when you need them. The Navy guys cringe at the idea of that
bubble, but it worked a treat, and was even included in the beginning
pilot's training classes, right alongside VBT-101 and all the
rest.
As to the fairwater vent valve size, bigger is better.
George's were (are) too small. When I vent, I want to GO!, and I mean
right now. Three-quarter inch valves are, in my opinion, about the
minimum. One inch and up would be even better!!! That's for ball
valves, of course.
The Aquarius used pneumatic mushroom valves
designed pretty much after a dry suit vent valve, only bigger. The vent
area itself was an inch and a half in diameter (or thereabouts)
with a ring of half inch holes in the body. Pop the valve and out came
the air, and I don't mean maybe. You could vent a half ton of fairwater
ballast air in no time flat, and it was really nice to be able to get
underwater without all that waiting around.
Remember, anything
you can do to keep from spilling your coffee is worth a try. Wallowing
around in three or four meter waves is something you don't want to do
any more of than you have to. Taking that lesson forward, it stands to
reason that the more flexible you can make your sub, the more capable it
will be, and that translates to a better tool for you. It's a sort of
belt and suspenders approach, which I heartily approve
of.
Vance
-----Original Message-----
From: Dan. H.
<jumachine@comcast.net>
To:
personal_submersibles@psubs.org
Sent:
Mon, 17 Mar 2008 10:57 pm
Subject: Re: [PSUBS-MAILIST] MBT air
lock
Frank and Brian,
The MBT's are only used at the surface. When diving they
should be totally full of water and not used for depth control.
When the tanks are being flooded, all air gets expelled, even the air in
the line. That's how the water gets in the line. Once my
tanks are full of water I leave the vent valves open and never feel a
difference in buoyancy while diving..
The Variable Ballast Tank (VBT or hard ballast tank) is
what is use to adjust buoyancy. That's designed with all
ports closable so once it's set, the bubble can't shrink or expand while
your diving.
Frank,
It looks to me like your system will work since your lines is
sloped back. Any water caught in them should eventually
settle back in the tank, but you can't have any dips.. A three
eights line may be a little small though. It will take a long
time to vent and it's harder for air to travel up as the water runs
back. Half inch would be better. Water will be caught in the
pipe above the closed vent valve though. If it's low to the water
line, it may be blown out by the pressure in the MBT but if it's not, a
quick burst of fill air through your T will surely clear the line.
Still, I feel the better way to deal with the vents is to place the
valve right at the top of the tank and run linkage rather then
tubing. But it's not the only way. As long as you can
prevent water from getting trapped in the line or have a method to blow
it out it will work.
Dan H.
----- Original Message -----
Sent: Monday, March 17, 2008 2:04
PM
Subject: Re: [PSUBS-MAILIST] MBT
air lock
Hi guys. Is the air lock problem on the ballast tanks
due to the line from tank to valve being too long? Or is it that
the valve has a length of line above it that holds water ?
I know that the line can't have any low spots in it, or even just
run level, but must have a continuous up-slope. I remember Gary saying
his original installation had a low/level spot that trapped a little
water and effectively plugged the line, but he fixed it by moving the
valve higher. His valves are located outside the tower, with the
valve handles inside and a seal on the valve handle shaft.
It's a nice clean installation.
I am planning on running the lines into the sub, and using
a ''T'' with air line to blow the tanks, and the line exiting the sub
near the top of the hull. This method has the same number of
thru-hulls, but has more valves. One on each thru-hull, and one on the
''T'' for the air line. ( three valves for each tank.)
I think Gary's has a separate air line going to the tank
for blowing dry so basically one thru-hull for the air line and one
for the valve handle shaft.
My ballast tanks are several inches higher at the connection, and
I'm hoping that with the short length of the plumbing, I should be
able to avoid any blockage.
The hole in the bottom of the tanks is low and 3 inch diameter. I
was planning on using a 1/2 inch thru-hull for releasing the air. Does
anyone think that's too small ?
I'll try to put a sketch of the system up so you guys can comment
on it.
Frank D.
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