[PSUBS-MAILIST] Trim weight
via Personal_Submersibles
personal_submersibles at psubs.org
Fri Jun 13 11:07:45 EDT 2014
Scott,
The biggest hassle seems to be when you go from diving with a 230 lb
passenger to diving solo. I hope to come up with a method of
shipping/unshipping lead as conveniently as possible in such circumstances.
The formula for three people in a K-350 is the sum of their ages cannot
exceed 120.
Jim
In a message dated 6/13/2014 9:09:55 A.M. Central Daylight Time,
personal_submersibles at psubs.org writes:
Jim,
I have my passengers go from back to front and honestly it doesn't make a
huge difference. The egg carton idea is awesome if you make major changes to
equipment or passengers. For example if I am going to put another person
in. I have had 3 people in the sub and it is tight, but do able.
Thanks,
Scott Waters
Sent from my U.S. Cellular© Smartphone
via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
James and Scott,
I had planned to have the weight tray inside the hull with a screw drive
such as on a garage door opener driven by an electric motor in order to
adjust the trim. I think Cliff has something similar on the R300.
However I've almost abandoned the movable tray idea in favor of something
more like Scott's egg carton. Once the initial test dives establish the
proper trim, there shouldn't be a lot of need to reposition the weight unless
I add equipment. I have tandem seating so [Human+Lead] in each seat
should remain constant no matter the weight of the pilot or passenger. In the
K-350 where they could swap positions while underway, there might be more
need to move the trim weights. When you change passengers and/or pilots
you might have to add or subtract weights, so it's more convenient to have
the tray inside the hull.
Cheers,
Jim
In a message dated 6/13/2014 3:59:02 A.M. Central Daylight Time,
personal_submersibles at psubs.org writes:
One thing i did think about being a possible idea is a moveable weight
that can be cranked back and forth to adjust trim, a bit like you have on a
plane. Would be quite easy to do and would be handy for fine tuning trim.
Would need another through hull though. Another winter modification maybe.
Regards
James
On 13 June 2014 03:15, swaters via Personal_Submersibles
<_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) > wrote:
That is one way of fixing it. A bigger line would help prevent it some
times, but not 100%. Dan's solution works well. It isn't a major problem with
the K-350 design, just more a pain in the butt.
Thanks,
Scott Waters
Sent from my U.S. Cellular© Smartphone
Alan James via Personal_Submersibles <_personal_submersibles at psubs.org_
(mailto:personal_submersibles at psubs.org) > wrote:
OK thanks I see now.
So if the ballast tank air fill was on a T in the ballast vent line,
just below the
ballast valve, that would blow the water out when surfacing & solve the
problem?
Alan
____________________________________
From: swaters via Personal_Submersibles
<_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) >
To: Personal Submersibles General Discussion
<_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) >
Sent: Friday, June 13, 2014 1:41 PM
Subject: Re: [PSUBS-MAILIST] Bouyancy
Alan,
It normally happens after the first dive and water gets trapped in the
line. The gravity pulling the water is counteracted on by the pressure in the
MBT pussing the water up therefore the water is trapped not letting the air
out of the MBT.
Thanks,
Scott Waters
Sent from my U.S. Cellular© Smartphone
Alan James via Personal_Submersibles <_personal_submersibles at psubs.org_
(mailto:personal_submersibles at psubs.org) > wrote:
Dan / Scott,
I'm a bit puzzled by this.
There wouldn't be water in the line initially unless the valve exit was
facing upward & rain
or wave splash entered it. Does water enter in as the sub bobbles about &
the ballast
air exit dips below the water? I guess then the water in the line would be
held in place
by the small air pressure in the ballast tank, which wouldn't be enough
to force the water up & out,
but is enough to hold it in position.
Alan
____________________________________
From: Dan H. via Personal_Submersibles <_personal_submersibles at psubs.org_
(mailto:personal_submersibles at psubs.org) >
To: Personal Submersibles General Discussion
<_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) >
Sent: Friday, June 13, 2014 3:03 AM
Subject: Re: [PSUBS-MAILIST] Bouyancy
Scott,
To clear the lines, I screwed a T onto each of the through hulls that feed
air to the MBTs. (on the open end under the MBTs) Then I fashioned a
piece of copper tubing that directs a stream of air right into the MBT vent
line but not actually connected to it. I put a restriction in the other end
of the T to create enough back pressure so the tubing emits a pretty good
blast of air directed at the vent port.
To vent the MBTs, I open the conning tower vent valves then give the tank
blow valve a turn till I see the water blow up and out the vents. That
seems to clear the lines and then it vents properly.
It's not a great fix but it works.
----- Original Message -----
From: _swaters via Personal_Submersibles_
(mailto:personal_submersibles at psubs.org)
To: _Personal Submersibles General Discussion_
(mailto:personal_submersibles at psubs.org)
Sent: Wednesday, June 11, 2014 10:37 PM
Subject: Re: [PSUBS-MAILIST] Bouyancy
Dan,
I have the exact same problem with hydrolocking in the vents. I have to
open the hatch and blow the water out with my mouth. Pain in the butt.
Thanks,
Scott Waters
Sent from my U.S. Cellular© Smartphone
"Dan H. via Personal_Submersibles" <_personal_submersibles at psubs.org_
(mailto:personal_submersibles at psubs.org) > wrote:
If I were to do mine over again, I wouldn't vent it as it is in the plans.
Instead of running piping from the MBTs to the conning tower, I would run
linkage, and have the actual valves mounted on the MBT.
Besides slow venting, my biggest problem is getting water in the piping
that won't escape to let the air come through when venting. A homemade
mushroom valves made from bathroom sink drains controlled by linkage going to
the conning tower, or anywhere easy to reach in the hull, would solve all the
problems.
My thought, Dan H.
----- Original Message -----
From: _via Personal_Submersibles_ (mailto:personal_submersibles at psubs.org)
To: _personal_submersibles at psubs.org_
(mailto:personal_submersibles at psubs.org)
Sent: Wednesday, June 11, 2014 9:53 PM
Subject: Re: [PSUBS-MAILIST] Bouyancy
Scott, Alec, Vance, and all,
A 3/4" vent is going to be about 2.25 times as big in cross section as the
1/2" vent. A 1" vent would be about 4 times as big as the 1/2". What are
your thoughts/comments on 3/4", 1" or any other size vent vs another?
Thanks,
Jim
In a message dated 6/11/2014 5:45:10 P.M. Central Daylight Time,
_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) writes:
James,
I totally agree with you on the 1/2 inch vents being way to small.
Eventually I am going to switch mine out to 3/4"
Thanks,
Scott Waters
Sent from my U.S. Cellular© Smartphone
James Frankland via Personal_Submersibles
<_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) > wrote:
Hi All,
A member has asked me to post a description of what was going on with
bouyancy on my dive. Which was as follows:
I'd asked the crane driver to be prepared for the first dive to hold me
just below the surface as i was expecting to be a little out of control.
At first, i got a bubble stuck in the forward tank. Ive put quite a large
lip on the inside of the tanks in an attempt to cope with Guernsey seas.
I could see the bubble stuck through the forward dome and i squished myself
right up into the front to try and force it a bit more level so it could
escape out of the vent. It didnt make any difference and then all the lead
i had inside, slid along the deck right to the back, making the entire
situation worse. Closed vents, blew mains and re-surfaced.
Next attempt, i got the bubble stuck in the aft tank. This wasnt as bad
because the motor cut away allows air to escape so i got under a little
further, but not enough. I flooded the variable in an attempt to get under.
Still no good, so i asked the divers to shove on the back. This got the
boat under, but then because of the total lack of air in any tanks, i sank to
the bottom like a stone. Depth was 6m (20ft). I expected to stop on the
crane ropes, but the driver must have misunderstood me and before i knew
it, the bottom was in sight and then i was down with a gentle bump.
I sat for a bit talking to my brother on the radio and then shut the
variable vent and pumped a little air into the tank. I slowely started to rise.
Flooded it again and started to sink. Really quite straight forward.
Blowing the VBT completely brought me up fairly quickly until i seemed to
be just awash with the surface. Filling the mains then brought me right
out.
I did several more test dives after that and as long as i evened out the
venting of the main tanks to avoid the bubbles, i could dive without the
divers assistance.
I next got the boat neutral just off the bottom and then used the motors
to drive up and down. I was not aware at the time that one motor was not
working but it still seemed quite responsive and i could drive all the way up
to the top or down to the bottom, stopping anywhere in between.
I need to add some extra vents to the main tanks to prevent the air pocket
from occuring again, and also those half inch vents are far too small. It
takes forever to vent the main tanks. Thats one for a winter modification.
I think that was it.
Regards
James
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