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.&n! bsp;
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
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.
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