|
Dean,
It was a windy day when we did the unmanned deep water test on my
sub. First off, the wind kept us drifting down the lake. Second, the
water was choppy from the wind and the sub was on a nylon line. At 540 ft
it had some stretch to it. These factors made us need to keep an even pull
upward, no matter if the sub was moving or not. One person could pull
on the line but it took two to make progress because of the elastic nature of
the pull. We would both pull, then one hold and the other get a grip
farther down then repeat. With the elastic line we couldn't even tell if
we were actually hauling sub or just stretching line. When we got fifty
feet or so pulled up we figured we must be moving the sub. It's difficult
to estimate resistance. We were fighting so many forces that also includes
inertia of the moving sub with out tugs on the line, the weight we had to over
come and the water flowing around the hull.
The original plan was, the sub was to be weighted 30 pounds heavy with
expendable drop weights that were to be released by puling on a second smaller
line. That was attached to a release pin on top of the sub. I
figured, even if the lines wrapped around a bit, one would still slide by the
other. That didn't happen!
We had to hand haul up to about half way, then unwrap three twists in the
line. After that we pulled the pin and waited till the sub surfaced.
Let me tell you.... It was a great sight to see that yellow hatch break
the surface!
If I was to do it again, I'd use a electric weight release and send down
two wires with the nylon hauling line. That way wrapped wires and line
wouldn't be a problem. Or have a winch on the surface boat capable of 600
feet of line.
Dan H
----- Original Message -----
Sent: Saturday, February 07, 2009 9:28
AM
Subject: Re: [PSUBS-MAILIST] safety
chain
Dan good thought on a com wire. It sure would be
better.
Do you have an estimate of how much water resistance you
encountered.
I guess not a lot if you were able to hand haul it
up.
Was that the plan to begin with or a SNAFU?
This spring I will be installing a winch on my surface
boat.
Dean
In a message dated 2/6/2009 8:57:27 P.M. Central Standard Time,
Jumachine@comcast.net writes:
Dean, Frank
I don't have a float system on my sub but have given one some
thought. It would be pretty difficult to have a cable on the sub
capable of lifting the subs weight flooded. Mine was just about 30
pounds negative when we tested it on a line and had to hand pull it up
from 540 feet. Al Secore probably still is walking bent over.
Thirty pounds heavy, in rough water, with the resistance of the water
flowing around the sub as it rises is a lot more then thirty pounds hanging
on a hook in the shop. Any cable would have to have a reasonable
safety factor for rough conditions.
Also, having a way to communicate with the trapped sub would be nice
for the folks on both ends. I was thinking of making my float
pull up a wire pair from a spool on the sub. It could be used with
equipment you surface crew can carry for emergency communications and also
serve as a guide to send help down to you.
Your surface support crew can carry a latch mechanism that is designed
to mate with a mushroom shaped pin on top of your sub. If the
emergency alert line emanates from the top of the mushroom, your latch
mechanism can be threaded on the wire at the surface and slide down till it
hits the top of the sub and latches. Of course you first need to
attach a strong cable to the latch before you let it down. The big
question is, will there be a winch heavy enough and a cable long enough
available but you need the winch no matter how you do it.
We used to use a similar system to retrieve rock core samples from a
drill tube instead of pulling up the entire drill string. The latch
was sent down the drill pipe till it hit a mushroom pin on top of the core
barrel. It would catch and you started hauling it up.
I like the idea of wires to communicate through.
Dan H.
----- Original Message -----
Sent: Thursday, February 05, 2009
2:36 PM
Subject: Re: [PSUBS-MAILIST] safety
chain
Hi Dean. I think an 1/8 inch is way too small. We discussed this last
year and it's a good idea to have the ability to pull the sub up, but
carrying a spool/cable assembly on board will require a pretty heavy
set-up.
One idea tossed around back then was a float
and cable like you had planned, but the cable is used as
a guide for lowering a "clamp" that would be capable of
attaching to the sub to pull it up. That way the heavy "clamp" is carried
on board the surface craft where it's not exposed to sea water, doesn't
add any weight to the top of the sub, and can have a thick cable strong
enough to pull the sub free from mud or minor entanglement. Just lifting
the sub alone may not be enough if it's in the mud or hung up on
something.
It should be pretty easy to fabricate some type of
"hook and latch " device that the clamp can drop onto ( guided by the
float/cable ) and then be able to pull really hard if the sub got stuck.
An 1/8th inch cable would then be enough if used as a guide. Frank
D.
Great
Deals on Dell Laptops. Starting at $499.
Who's never won? Biggest
Grammy Award surprises of all time on AOL Music.
|