Sunday, July 3, 2011

MOB Drills, Lifesling, and Climbing Equipment

rev. 9-22-2016

What to do at the end of a hot summer's cruising day, when there is nothing that really needs doing? Not practice MOB procedures, that's certain.

I cued a movie to watch while dinner was simmering, "Morning Light", about a Disney Transpac team, and it had a bit on MOB procedures. With a full crew, of course, you simply muscle the bloke back on deck. With a family boat, you need something that will work for the smallest person recovering the largest, and given the crap tasks Dear Dad often draws on rough days, he seems most likely to go for a swim. It also has to be simple enough to remember. And so we found ourselves beginning a long over-due MOB practice.

We've practiced picking up objects from the water, so getting along side, or at least within Lifesling range is a known challenge. Actually testing the Lifesling is another matter.

On the PDQ 32, using the spinnaker sheet seems obvious; it wouldn't be in service at the time of pick-up, there are two dedicated 2-speed winches on each side, and it's long. The boom can swing over much of the stern of the boat, is easily positioned with the traveler and if needed, a line forward to the midships cleat. All that is needed is a boom end carabiner and a climber's rescue pulley. A rescue pulley is a sort of simple high strength snatch block, optimized for quick deployment and simplicity, and rated for lifting man-size loads. We keep these clipped to a pocket by the helm seat at all times; you never know when a snatch block and biner will serve some work-around or as a genoa lead. The working end of the spinnaker sheet simply goes up to the block and down to the victim and can be set-up in seconds. DON'T use the spinnaker shackle to attach the victim; the damn things open too easily when dragged across a surface; tie a figure-8 on a bight at the end and use a carabiner to clip either harness or life sling.

There are 2 gate locations on each side of this boat: the sugar scoops and the aft outside of the hull. We tested both with the kayak, just to see the run of the lines. Very smooth either way and only two fingers were required to turn the winch.

So, what happens with real weight on the line? We tested it with a human, the lightest crew lifting the heaviest.

  • Dad moaned when Jessica paused to take pictures. Hanging by your armpits is less than comfortable, but not injurious or bruising. Aggravating, though, when your daughter talks of just leaving you there.
  • Jessica did not need to use the lower winch gear; she could easily have lifted a much heavier person.
  • It's difficult to get the person's body high above the deck, but simple to use the mainsheet and traveler to move the boom and drag them onto the deck once their fanny reaches deck height.
  • Maintain a good 1/2-inch topping lift or make sure you back it up with the spinnaker halyard. The load on the boom end can reach about 1,000 pounds (500 pounds dynamic load plus the doubling by the tackle plus other rigging loads); you want a good safety factor.
  • Raising the boom by shortening the topping lift would be a good idea. I think the optimum is to hoist the swimmer until their knees reach the rail, and then pull then onto the boat--higher would swing too much in rough conditions, while keeping contact with the side of the boat prevents this.
  • Is it better to haul a person up the sugar scoops or the side? The best choice depends on the swimmer's condition: if uninjured, the sugar scoops would be simpler and safer in most conditions; if injured or unconscious, hoisting over the side is very straight forward.
  • Hoisting by Lifesling is far more comfortable than hoisting by harness; I would use the Lifesling to hoist an injured person (not chest injury), though I might clip the harness for added security, particularly if I thought they might have difficulty holding on. The Lifesling would be attached with figure-8 and biner and the harness would be clipped, with slack, to the shackle in the spinnaker sheet.
  • People have fallen out of slings before, generally because they are panicking and trying to hold on to
    the sling, rather than simply keeping their upper arms down. In the first picture, my arms are down and my hands are merely resting on the sling. Later I grabbed the sling so that I could more easily lean my head back and see where I was going, and to swing my feet up on deck. However, always instruct a tired or injured person to keep their arms down.
  • Though clipping the webbing of the Lifesling directly might be more secure, it seemed impractical. We clipped the lowest point that could be reached from deck if the line was hauled by hand first.
  • Want to winch using the Lifesling line, rather than clipping a sheet? We tried that but weren't happy with the way the floating line worked on the drum and the Lifesling line would not function in the self-tailer. Additionally, you would need to use a second rescue pulley and biner clipped to the spinnaker block to create a fair winch lead; easily done. Certainly this could work if clipping the sheet is not practical on your boat. But I would test it and consider upgrading the Lifesling line to a more winch-friendly floating line. Yellow is good and it must float very well, as getting the line tangled in the prop or under the rudder would be life-threatening to the swimmer.
  • Want to winch using the harness instead? We wouldn't, though we would clip the harness to a tether as a back-up. The lifesling is more body-friendly than most harnesses, as it is well padded.
  • Locking vs. non-locking biners. Non-climbers and beginners always assume a locking biner is safer. Well, sort of. On the boom end a locking biner would certainly work, but there is virtually no chance of un-clipping and the fall is not serious. Perhaps a locking biner is better practice, butt he difference is trivial. On the swimmer end, a non-locking biner is probably safer because of speed. Even if the locking mechanism is not used, it can tend to catch on the rope, and speed an ease of hooking will be important while you are leaning over the rail. Speed is the reason climbers use non-locking biners for most purposes; faster is often safer when you're struggling, and non-locking climbing biners clip in a flash, much more easily that their marine counterparts.


Better yet, wear harness and tether, stay on deck, and avoid the whole business.

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