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Re: [PSUBS-MAILIST] safety chain



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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