Mooring pendant twist

[Andy Denmark]

In another fruitless attempt to get a good picture of my resident heron with a pretty Cape Dory 30 in the background (Farmerchase's Anne Freeman), I was again reminded to tap the wisdom of those who keep their boats on moorings regarding twisted pendants. Attached is the heron pix and another closeup of the pendants.

Here in God's country we have no lunar tide. Broad Creek, where I live, is not truly a flowing creek but more of an elongated tributary so there is no tidal influence. The twist in the pendants seen here is a result of the rotational pattern of the summer wind.

There are swivels in the mooring attachment to the anchor but they are galvanized with correspondingly high friction and don't swivel if there's any load at all on them. This is a logical idea at the concept level that doesn't work in reality (sounds sorta' like our economy ).

Does anyone have a solution to this problem? My concern is with the pressures on the bobstay should the twisting get too severe, both inline and side-load. With hurricane season upon us it would be nice to have a viable answer. It is no problem to dinghy out and untwist things from time to time but when the hurricanes are nearby and it's blowing 90 kts with big swells coming up the creek things get a little testy. Any suggestions are appreciated.

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[SurryMark]

Looks like she has been practicing secret rolls in the night. Are there broken eggs on the overhead? Do you have a "tall boy" pickup? Are you careful not to add a twist when you haul it on board?

[Ron M.]

I have a swivel below and above the mooring ball. The upper swivel is shackled to the mooring chain above the ball and rides on a tire rubber donut.
I have 2 3/4" pennents that are seized with 1" foam pipe insulation covered with a multilayered, stretched, vinal tape, tight !. The seizing stops 3' from the eyes,(2 bow cleats) to form a bridal. The other ends have eyes with stainless thimbles that are attached to a 3/4" oblong ring,(I forget it's nomenclature) that is shackeled to the upper swivel. The pennents are Yale Cordage multibraid,(yellow). I discussed my needs with the head rigger at Hamilton Marine, and this is what he suggested.It has worked flawlessly for 3 years now.Occasionally I will get a twist or 2 but it's much better than the 3 strand system I'd used for years. They figured with seasonal use it should last 8 -10 years. It wasn't cheap, 300.00, but for peace of mind, well worth it. One can't leave the boat unattended, on a mooring for weeks on end no matter what you use.
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[Bob Owens]

Andy,
I am not sure I have any advice to give you, but here is my situation. I am in western Long Island Sound where we have daily tidal falls of around 7 feet, in addition to the wind shifts. Our mooring company will having nothing to do with swivels; says they (a) don't work, and (b) create a weakness in the rig. Therefore, I just build into my routine a check on the twist issue every 4-5 days. My mooring tackle, starting from the anchor, is a length of very large, heavy chain which lays on the bottom mostly, joined to a length of lighter chain, which ends in a ring, to which the mooring pennants are attached. The float-ball is also attached to this ring separately with smaller chain. I notice that in heavier winds, stong enough to lift some of the chain, the chain gets twisted a bit and then lies back on the bottom. That twist will convey itself to the pennants unpredictably--nothing during some calm days, then a hard wrap once the wind pipes up again sometime enough to lift the chain. My routine, at least once a week, even if the pennants are not twisted is to lift the whole rig up enough to get much of the chain off the bottom. That will enable me to get out any twist that may be lurking in the chain. It is a bit of a heave to get that chain off the bottom, but this has proved important for my set up. FWIW
Bob

[tartansailor]

My mooring buoy is the type that has a cylinder as it's axis.
From the bottom swivel, a chain runs up, through the cylinder inside the buoy, to a flange, thence to a big wide D shackle which holds the chain up.
From the shackle, another swivel, then to the pennants.
At the time the boat was moored in a river with a substantial tidal flow,
and to my recollection there was only one time we experienced a twist, and that was after a frightening blow.
I remember that vividly because lazy me did not have chafe protection, and the pennants melted to about half diameter.

Dick

[Oswego John]

Our mooring company will having nothing to do with swivels; says they (a) don't work, and (b) create a weakness in the rig.
Bob

Hi Bob,

I guess that when you are in Rome, you have to do as the Romans do, or at least do what they tell you what you have to do. My guess is that you are moored in a private or a commercial mooring field. No swivels, huh? I suppose that if you go against the mooring company's specs, you void their guarantee and you'll find yourself looking for another mooring spot next season.

For every company that forbids the use of a swivel(s) on a mooring setup, I'll bet the farm that there are a dozen or so harbour masters and fleet captains whi insist that a swivel musr be used.

Swivels do work. Well, maybe not the made in China super whiz-bang cut rate swivels that use aluminum paint instead of galvanizing. Swivels create a weak spot in the rig? I'm not buying what they tell the customers. So go up a size or two. If you use 5/16" chain, then use a 3/8 or a 1/2" swivel. Same thing goes for shackles.

I used to be in the business of setting and pulling moorings. The vast majority of mooring troubles were caused by unbelievable DIY homemade moorings, moorings that weren't protected by a swivel(s) and hot spots in the area that caused electrolysis that ate away at the upper portions of the mooring chain.

While I'm on my rant, I'll add one more thing. I think that it is a good thing for the mooring's catenary curve to have the lighter, upper chain lift the lower, heavier chain during a heavy blow. This action works as a shock absorber to prevent excessive shock from the lower mooring to the bit or bow cleat.

Andy:
Some people who use a double pennant permanently attach a spreader between the pennants, about half way between the ball float and the bobstay.

Let's see, now.

Tiller or wheel
Lock prop or not
Morey's red or Morey's green
Swivel or no swivel

I believe it is time for a Dark and Stormey or three.

Yeah, that's it. Probably three. Wooo Hooo

O J

[Jim Sullivan]

Andy:

From your picture, it looks like you have a double mooring pendant but it is unclear if both pendants attach to the top of the float. Looks like something (line) is going to some point below the float. Is this correct? For the type of float that you have, both pendants should attach at the top. The setup I have always used is a double nylon pendant the connects directly to a swivel that is in turn attached to the upper chain. The mooring float I use is the type with the connection point on the bottom. Either type of float should work for you. What I have found to correct the twisting problem is to join the two pendants to one another at approx. 1-foot intervals beginning where they attach to the mooring chain (float, in your case). I do this using 1/8" nylon and whip the two pendants together. I have a 10-foot double nylon pendant with the first 6-feet joined as previously described. I have never had a problem with twisting since I have been doing this and I have not had a problem with the pendants becoming unconnected. Good luck.

Jim

[Bob Owens]

John,
You are correct: our club contracts with a firm to see to all our moorings. He (VERY independent-minded on a lot of fronts) outlaws swivels, so we all have to abide. He does a great job looking after things generally so we don't kick about the one or two quirky issues.
Bob

[Andy Denmark]

Cap'n Ron and I rowed the dinghy over between thundershowers to check this out. What we found is surprising and nearly inexplicable but I'll try.

First, the pendants are shackled to the ball, one to the top and one to the bottom. The swivel under the ball freely rotates and is in good shape (except all of the galvanizing is gone on everything due to use of stainless seizing wire on the shackle pins). The chain to the anchor was not torgued at all.

The two pendants are 3-strand 5/8" nylon and are secured thru good chafing gear to the bow cleats. Both are the same length ostensibly to share the tensile load equally. As strange as it may seem this may be a big source of the problem.

Here's why: a lot of the time the pendants are lying next to one another, usually with first one and then the other under tensile loading as the boat twists in the wind (or current). A small percentage of the time they share the loading equally and at other times they are slack and droop into the water. This soaking softens the line. Being two lengths of the same line they are dimensionally identical. This means that a strand of one line can rest in the groove between two strands of the other line when they're touching. This "mating" occurs along some length, not just in one spot. This "nestling" and wetting with a cyclical load where the lay of the line probably opens and closes some with the variable tension results in a "melding" of the two lines -- one strand works its way into a corresponding groove on it's counterpart. This process is a continuous thing as the two lines hook together in this way. This sort of "connection" occurs simultaneouslywith the other two strands. Because the "lay" of the line twists in one direction the "melded" line tends to follow this twist along its length, further bringing the lines together into a nearly-solid piece of 6-strand "line." The two lines literally weave themselves together.

This sounds really weird, I know, but what we saw seems to bear out this finding. The two lines were firmly wound together and were difficult to pull apart because they were intermeshed. When they did come apart they wanted to "kink" like a piece of 3-strand that had been untwisted. There was a definite torquing component here. The only way I can resolve this in my head is to see this "melding" action occurring close to the ball and working its way up the pendants, joining the two lines together into one as this "melding" action travelled upward until hitting the bobstay. This would mean that the twisted-together pendants actually rotated around themselves and rotated the mooring ball. This twisting phenomenon could not have happened unless the boat rotated along its axis (barrel rolling if you will). That ain't gonna' happen!

Soooooo --- how do you stop this? First, never make the pendants the same length or the same diameter. This should alleviate the tendency to do the "melding" thing as nothing fits together anymore. Second, for safety I'd make the shorter pendant the smaller diameter one, the reasoning being that if it were to chafe thru or break then the larger, longer pendant would be more secure.

Before everyone jumps on me for having too many Dark & Stormies, I'm interested if others have seen this phenomenon and/or derived the same explanation. It's certainly a curious thing that i've never seen and I might be totally incorrect with my analysis. Oh, I took the camera on this outing only to discover that I left the memory chip in the computer! So, no pictures.
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[Ron M.]

I have not seen the melding, as you describe it, of 2 lines of 3 strand polyester.......but I can imagine it possible. I used to moor my CD 25 on a tidal river with a strong current and open to the SW. It had 1 pendant of 5/8 3 strand polyester. Swivels above and below the ball. Many times the mooring pendant line had completely unlaid. It never abraded or chafed, but it was a pain in the ass. I didn't ever solve the problem and it didn't occur all the time, but it was unsettling when it did.
When you have a bridal pendant it is recommended that one be a bit shorter. As I mentioned previously, nylon/polyester mooring pendants, with the multibraid cover remedy a lot of problems, are very strong, and last a long time. I think they are worth the money and recommend them.
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[Bob Owens]

Andy,
I have to say that I have never seen the two pennants divided to attach, respectively, above and below the mooring ball, as you describe. My seat-of-the-pants guess would be that this would increase their tendency to wrap. But I have absolutely no expertise on the subject, or experience with that type mooring ball.
Bob

[Ron M.]

I missed where you mentioned one line below and one above the ball. That would certainly contribute to your wrapping probem, if not be the direct cause. I see no benefit to that arrangement.......at all. I have seen both below, on a swivel. Nantucket's transient mooring field is set up this way and seems to work well.
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[chase]

Thanks all for the input and particularly Captain's Ron and Andy for looking out for Anne Freeman.

I installed one line below the mooring ball to try to prevent the twist that happened when both were connected above the ball, or both below the ball. Several times over the winter I arrived to find no twist at all, just chance I presume. It makes perfect sense that they would....

Never have they melded in the way that Andy described but when I tied back up this time, the lines were wet and a little slimy so this must have contributed.

Anyway, this is all new to me so I'm looking forward to resolving it.

Chase

[Maine Sail]

The top/bottom connections are exacerbating the twist. Follow me for a moment:

In light winds/no winds the boat circles the ball. Because there is so little wind the top pendant flips and circles around the ball while the lower line wraps the chain due to insufficient pressure to spin the swivel. You now have a twist because the two pendants went around the ball at different times.

Perhaps when I get some time I will post a how to on pendants/balls/connection points. There are some tricks but I am on the boat and don't have the time right now to get into it in depth.

[Andy Denmark]

Attached picture taken at 1330 today, 7-18-09. At 0630 both pendants were separated. Wind has been relatively steady today, W to WSW at 0-6, no current. At 1330 there appear to be four twists. Swivel under ball is free to rotate. Boat has not (to my knowledge) changed its relative position to the ball. Something is rotating here and it's not the boat.

Maine Sail -- I'm interested in your take on this. We are "mooring illiterate" down here.

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