Thursday, June 30, 2016

Is the Stainless Swivel Eating the Zinc off the Anchor?

Look like it to me. (not my boat)

This is also a good argument for a galvanized shackles. Stainless chain hooks may slide on and off a little easier, but over times I suppose there is some effect, if you are on the hook a lot. I just go all-galvanized.

Personally, I can't see much use for a swivel. The original SS swivel on Shoal Survivor (15 years) revealed an incipient crack when I took it apart to install a new anchor. No thanks.

(not my swivel, but it shows what side leverage can do)

  • Align the chain between the anchor and the gypsy. The chain can't spin in the gypsy, can it?
  • Motor/draft backwards if need be; most anchor will alight due to water flow.

Monday, June 27, 2016

How Long Should a Tether Be?

The 3' / 6' split has become a defacto standard, since these are the lengths in the ISAF standard. Well, sort of. What it actually says is that:

  • 30% of the crew (or everyone if you single hand) must have a tether leg of no more than 3'.
  • Every tether must be less than 6'6".

First off that means you can, and perhaps should have tethers less than 3'.

This tether is only 30 inches, is attached well in-board, and I'm well outboard. Of course, I had to climb over the high lifeline.

 At the mast in lump weather I sometimes go even shorter. How about a vertical jackline. Every boat should have these available in the form of halyards, though mine are fixed (they serve an unrelated tangle-avoidance function).

Additionally, I see no reason they cannot be longer in certain cases. My other leg is 8', bout right for the broad bow of a cat. I can imagine much longer on bigger boats. You just have to use the length intelligently.

What about smaller boats? I was fooling around on this 27' mono, using Amsteel jacklines, and concluded that the longest leg should be 3' and the shorter perhaps less than 2'. A 6' tether has no place on a smaller boat. If you would like a longer tether for the cockpit, then have a separate dedicated tether there.

I like custom sizes. I fabricate mine from 8mm climbing rope using sewn splices, but climbing webbing and knots will do nicely.

Saturday, June 18, 2016

Renovating a LifeSling

A reader wrote into Practical Sailor that his LifeSling had basically fallen apart, the result of UV exposure. The blue webbing straps tore under hand pressure (a write up in PS will certainly be forthcoming). The age was uncertain (probably more than 20 years) and I believe it may have been stored upside down, since the straps should be on the bottom, completely protected from UV.

But the other issue is that the LifeSling cases are notoriously UV sensitive, or rather parts of them are. I bet the failed LifeSling was in a failed cover. The coated polyester itself is pretty durable, but the stitching goes and all of the Velcro fastenings go at about year 5-10, depending on the latitude and whether it sits on the rail year-round, like mine does.

Packing. Packed according to the instructions, all of the critical parts are well protected. The line (VERY vulnerable is in a tube in the center, with the sling over it; triple protection. After 19 years, mine is still pritine. The tail of the rope that attached to the stanchion base is covered with webbing. Although the webbing is sunburned, the rope is fine.

I cut a section open to look. Note that there are a few failed strands on the lower left, where sun must have peaked in. Polypropylene is touchy stuff.

Velcro Top Closure. I dislike the UV vulnerability of Velcro, so I replaced it with a tubular webbing and pin system, something like a door hinge. Just pull the red flag. This endured for 10 years without damage, so I left it alone this time. Durable, secure, and fast.

Velcro Ties. Really, a stupid application, when a knot will do better and last forever. Again, the Velcro fails in 5-10 years, I cut the remaining stitches, attached a 2" x 4" webbing strip on the inside with Sikaflex, a 4" circle of Sunbrella on the outside with Sikaflex, and punched a pair of holes. I was going to install grometts, but the laminate was too thick, about 1/8", so I simply threaded webbing.

Stitiching. Some of the seams had gone at 10 years, where they rubbed on the rail. I hemstitched them 10 years ago using whipping twine, and they are still fine.

Paint. I had some white vinyl inflatable paint left over, so after a good TSP scrubbing I painted the whole thing to provide some sunscreen (I masted off the instructions--that section seemed OK and has no seams or stress points). I have used Kilz primer plus house paint on projects like this before, through, so don't run out and by special paint.

I will 20 minutes work I should get another 10 years from the cover. Since the initial cover needed repairs at 10 years, I'm OK with that.

Sunday, June 5, 2016

Mooring Between Pilings

With the approach of hurricane season, I look forward to another season of watching people add lines without a plan. They double lines to cleats that are too small,  underestimate slack requirements, and put lines the wrong places. I've got a long article on dock lines and forces coming out next month in Practical Sailor. I

got a lot of funny looks, sitting on the dock edge during gales and squalls, taking reading on on line tension on both my boat and others using a block and tackle and load cell. Just two thoughts here:

Instead of adding a spider's web of lines that take loads in unpredictable ways, try a simple pattern of full spring lines. If you squint, notice how they form 4 over lapping Vs, with redundancy in every direction. Additionally, no cleat has 2 lines on it. (the double green/orange lines refer to data in the article--they are single lines.) This is how I tie my boat every day, and it really minimizes motion. Because the springs are actually continuous from piling to piling, they only take seconds.

Which brings us to the mind-ships cleat hitch. Because it is only one line but must be secure in both dirrection it is just a little different. Basically a standard cleat hitch, with a crossing turn after the locking hitch to reverse the rotation, and one more round turn. Very easy and clean.

The end result is that I can break any combination of 2 lines and still stay in my slip. The other result is that I don't wear lines, because they are always sharing.Easy and robust.

I have another article on  bulkheads in progress. More load cell testing. The interesting take-away from that one is that I use polyester spring lines (on bulkheads only--nylon between pilings) to reduce fender movement.

For storms I would add a few more, but that is another story.