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Hi Dan,
Thanks for the great input.
Best Regards,
Jim K
----- Original Message -----
Sent: Sunday, March 23, 2008 12:31
PM
Subject: Re: [PSUBS-MAILIST]
Instruments
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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