Friday, February 25, 2011

Soft Shackles, Stropes, and Square Riggers

Amsteel and other high-tech lines have made crazy things practical...
  • All-fiber standing rigging
  • Fiber lifelines
  • Safer jacklines
  • Fiber shackles
 ... except now that I think about it, none of this is completely new. It's where we started, when the first sailor decided to raise a few sticks and a woven mat above his raft to save paddling home. Clearly, we've improved on those early efforts. First, we used tarred steel, and then stainless steel. Heavier and more expensive, but durable and non-stretch with great abrasion resistance. But we couldn't leave it alone. I'm glad.

Traditional spliced strope with wall knot stopper
One of the biggest trends we've seen in the past 50 years is away from things that can be made to things that must be purchased. Given the steady decline in the basic shop skills of the average sailor and the increase in the complexity of our world, this trend is unstopable. But I try. Many of us try, and that is one of the great attractions of Amsteel; that a DIY sailor can replace purchased rigging services and create something better. I like that too.

Soft Shackles. A cool little invention: the only thing is the idea is about 200 years old on boats, and as old as ropes in general. Every pre-teen girl learned to tie these when braiding friendship bracelets. Every old salt learned to tie a strop with a splice and a turkshead; They are strong, cheap, and won't jam if loaded sharply. I've seen them used to arrest cannon. Rather similar, I think.

Still a good idea today. When made from Amsteel...
  • As strong as steel
  • Won't scratch the gel coat
  • Light
  • Cheap
  • Quiet
  • No tools required to install of remove

Colligo Marine style soft shackle above.
Kolohov style shackle, below.

Not Difficult to make, just a diamond knot and a 12-strand splice, which has the nifty trait of sliding open and closed. 

I learned of the old style strop from The New Glenans Sailing Manual over 20 years ago. There they were recommended as a means of attaching jib sheets on a dingy that was releasable and not likely to draw blood when changing a flogging sail. However, their method was simpler, taking only seconds to make, a minute if you're meticulous. The instructions, below, are for 1/8" line, but it will work in any size; I've made them up to 1/2" line, which will hold over 8,000 pounds  (the line is doubled).
  • Cut and seal a 12-inch length of 1/8-inch line. This can be longer, much longer, if a longer strop is needed.
  • Double the line and tie an overhand loop near the bend, with the loop just large enough to pass a double overhand loop on doubled line without having to force it. Tighten by hand and with a fid in the loop.
  • Tie a double overhand loop near the end of the loop. Leave enough tail to help pull the knot through.
For frequent use the eye is easier to thread if the loop is spliced and thus the tail is only a single strand. Often I use only the cover or core of a line (single braid), as it is soft, super easy to splice, and generally free (throw-aways, from core or cover stripping). For example, my mainsail gaskets are spliced cover-only.

Notes: A double overhand works as well as on double braid as a diamond knot; it simpler and though smaller, presents a very sharp edge and thus is perhaps just as opening resistant as the latter which is more rounded. A turkshead works in 3-strand, where a tight double overhand is impossible. A single line works fine for longer stropes. Webbing is a mistake; depending on how the webbing lies, there may be no sharp edge on the knot. The loop can be spliced or seize, but that is just more complex; I use the bulk of the knot to advantage on tarps and awnings by tying the knots on either side of the grommet, keeping the strop captive and safe from loss. Strength loss in the knots is largely irrelevant, as the strope fails where the loop cuts the stopper knot.
    Done. I've used them for 20 years to secure tarps and awnings on my boat. I've never had one shake loose. Larger per unit strength than Colloigo Marine-style soft shackles and considerably more bulky, they still come in handy due to shear ease and simplicity.

    I've tested a number of these, in different materials, to failure; they never slip and always fail by the loop cutting the tail knot off, at about 160% of the single line strength... unless made of Spectra, whereupon the the stopper knot becomes undependable diamond knot more reliable. On single braid Amsteel a tuck splice is faster than a knot and thus we have the Kohlhoff type, which is easier to remove after loading.

     To the right, a different style loop sewn from old 5/16 polyester.
    Broke at line strength.

     Some applications, some for Amsteel shackles, some for polyester stropes:

    • Attaching tarps and awnings. No knots to jam and no chance of scratching the gelcoat. Any length you want.
    • Securing the horseshoe life ring; strong and fine in UV (unlike Velcro or bungees), yet can't jam.
    • Sail gaskets. Unlike Fastek fasteners they won't shatter when you step on them, are easier to manage than knots with gloves on, and never jam. This is my every-day use.
    • Non-jamming reef knots (multiple knots accommodate 1st and 2nd reefs).
    • Securing halyards and preventing slap. Less noise and no scratching of the mast.
    • Towing a tube full of kids; a metal shackle would make the floating tow line sink and a knot will jam. 
    • Chain-to-snubber attachment.
    • Securing rope coils
    There are more modern solutions, but this remains a useful trick to keep in your toolbox. A gift from the golden age of sail.

    and this from a 1976 Sail Magazine article on tall ships (that was the year of the Bicentenical and the big get-together; Rememmber?


    Tuesday, February 22, 2011

    Messing About in Boats

    At some point we become so accustomed to winter it loses its bite and 45 degrees seems warm. Too warm for snow and ice sport, at least, if not warm enough for lawn chairs. We've spent too much time in the house, whatever task were assigned are either finished or won't be. Sunday was such a day. The wind had blown 30-50 knots from the northwest for days and there wasn't likely to be much water in the Bay. Never mind. It was time to get out of the house.

    It was still cold mid-morning and the water was very low, but I was unconcerned; the sun would warm the deck, the heater would warm the cabin and the water would come back by noon since the wind had stopped. I had a few lazy things to do.
    • Fit a new chain hook design, fabricated while bored in mid winter. I didn't like it so well as this one: Chain Hook For Catamarans
    • Measure the holding tank vent and ruminated on changes. I'm doing a new bit for Practical Sailor on the subject and one's own boat is always the primary test bed, the experience best understood.
    • Bum some Phifertex and Sta-Glas scraps from the local canvas shop. They often have mercy on those with tiny repair needs.
    • Uncover the tender. Heavy snow seems unlikely (we got a few inches 2 days later, of course)
    Those things didn't take so long. I started the engines, allowed them the the long warm-up winter requires, threw off the lines... and went 3 feet before the mud grabbed the keel. Well, no surprise, really; I brought a book and lunch and would make use of them. No hurry.

    I decided to poke around in the tender, having fabricated a few reasons: it needed air, which can only be added when floating; I like to run some gas through it on a regular basis; I'd seen a sailboat aground in the harbor entrance which I might visit.

    The boat was still there, aground for at least 5 hours, much of that with sails up. I don't know why he left the sails up, as they were only driving him further on. His first question to me, after a greeting, was about the location of the channel and when had it moved. The neat double row of red and green day marks 20 feet to his north didn't register, for some reason. He was well and completely stuck, though not leaning. His boat was also in such repair that calling Seatow seemed unlikely.

    Having nothing to do, it seemed only proper to give what help I could. I've never had a serious grounding of my own nor any opportunity for real practice, and learning is always worthwhile. After many years of paying for towing insurance I let it go this year; I've never used it and likely never will. With 2 engines, sails, anchors, and a tender, I can't foresee many situations I can't work out that would be still be considered simple tows. I would also, right or wrong, consider a tow embarrassing.

    I ran out an anchor for him (note: a 25-pound CQR is a heavy kedge; a Fortress is MUCH better) without any difficulty. Good practice. But it didn't help. I took his jib halyard, tied an additional 75 feet of line to it, and hauled that to one side to heel the boat. She leaned nearly to the rail did turn in the direction of the anchor, toward the channel, but didn't move far. We didn't break anything, but neither did we free the boat. Still, the tide was rising quickly and within an hour she lifted just enough to winch herself free, just as the tide reversed. A few hours later, my new friend was over the horizon.

    Shoal Survivor too, had floated free. There's not much to tell about a quiet afternoon on the Bay. I shared my bit of the horizon with only 3 boats. I read a few chapters of fiction, walked the deck listening to the whisper of the water, and enjoyed a cold beer. There would be no crowd at the marina to nod approvingly if I docked well in the cross tide, or to empathize if I didn't.

    I tucked her back into bed for a few more weeks of rest. Summer's coming.