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post #11 of 22 Old 11-04-2012
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Re: Polyester sling for chafe control

I think you will find that climbing ropes and caving ropes are just about impossible to splice. The covers are too tight (to reduce snagging on rocks).

Why not just use external chafe protection in the form of a hollow webbing sleeve? Easy.
Sail Delmarva: Anti-Chafe Gear

I would think aramid would be a poor choice because of it's poor flex life over a sharp edge (chock). Spectra would be better, and I believe there are Spectra pendants on the market.

(when asked how he reached the starting holds on a difficult rock climbing problem that clearly favored taller climbers - he was perhaps 5'5")

"Well, I just climb up to them."

by Joe Brown, English rock climber




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post #12 of 22 Old 11-04-2012
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Re: Polyester sling for chafe control

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I would think aramid would be a poor choice because of it's poor flex life over a sharp edge (chock). Spectra would be better, and I believe there are Spectra pendants on the market.
While I realize that the lack of stretch would reduce friction, I would still be worried about the relatively low melting point of HMDPE. Guess I'll stick with the stuff I understand.
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post #13 of 22 Old 11-04-2012 Thread Starter
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Re: Polyester sling for chafe control

What about sizing a bridle or pennant? Should it be slightly bigger that the size of line used in the rode? I'm not even sure about choosing the correct size of the rode. Rope inc. has a chart for this but it lists rope diameter based on the length of the boat. Wouldn't it be better to select the diameter needed according to the boat's displacement?
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post #14 of 22 Old 11-04-2012
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Re: Polyester sling for chafe control

The tables I have seen all have a star somewhere that say to adjust your line size also based on displacement - you also need to take windage into account as the more the wind can push on a boat the higher the load - - the higher the wind speed and current the larger the rode required also - - so it all goes back to the "guidelines" disclaimer


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post #15 of 22 Old 11-04-2012
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Re: Polyester sling for chafe control

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I didn't know that Dacron and polyester were one and the same thing. Huh. Learn something new every day.
Not a problem; we should all be learning something all the time.

In my line of work (like the pun?), I handle all sorts of exotic cordages, as well as cheap floating polypropylene, everyday nylon 3-strand, and run-of-the-mill dacron (polyester) double-braid. Smaller lines stretch more for a given load. So does 3-strand over double-braid, over parallel-strand.

So... the approach I've taken for my own boat is to use a good dacron (or you could use single-braid spectra, such as Samson AmSteel) pennant from the cleat through the chock, and then go with 2 lines out of that -- one very stretchy (for the "rubber band" effect), and one a little longer and more stout to overcome larger loading. Works well. Minimal chafe, easy motion, and secure tie-up at the dock.

For anchoring a bigger boat, I like chain, with a nylon snubber line at the boat end. For a small boat, in smooth/soft bottom conditions, the rode could be over 50% nylon spliced to a generous amount of chain at the anchor. A catamaran would call for a bridle to "connect" both bows together, distributing the load, and helping to keep the bows to weather. For permanent moorings for monohulls, we also use a bridle. In any of the scenarios, you get the same effect -- stretchy initially, and yet very stout when severely loaded.

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post #16 of 22 Old 11-04-2012
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Re: Polyester sling for chafe control

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While I realize that the lack of stretch would reduce friction, I would still be worried about the relatively low melting point of HMDPE. Guess I'll stick with the stuff I understand.
Not a problem. Tugs use HMDPE. Heat will only build if the fiber is absorbing energy and doing work, in the physics/engineering sense. No stretch no heating.

Samson-The Strongest Name in Rope, High Performance Tug Lines

The heating problem is confined to fibers that stretch a lot, absorbing energy. Cover the Spectra with a polyester webbing jacket and you have something VERY durable.

(when asked how he reached the starting holds on a difficult rock climbing problem that clearly favored taller climbers - he was perhaps 5'5")

"Well, I just climb up to them."

by Joe Brown, English rock climber




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Re: Polyester sling for chafe control

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The tables I have seen all have a star somewhere that say to adjust your line size also based on displacement - you also need to take windage into account as the more the wind can push on a boat the higher the load - - the higher the wind speed and current the larger the rode required also - - so it all goes back to the "guidelines" disclaimer
That makes much more sense to me. I recall a piece of advice that suggested going up one size over the recommended anchor weight and rode diameter. It seemed like reasonable advice, especially with the anchor. I would think that one could get out of hand with the rode though. It seems to me that using way too large of a line for rode would reduce the amount of stretch it could give and so reduce the shock absorbing effect of the nylon. I could be wrong about that though.



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Not a problem; we should all be learning something all the time.

In my line of work (like the pun?), I handle all sorts of exotic cordages, as well as cheap floating polypropylene, everyday nylon 3-strand, and run-of-the-mill dacron (polyester) double-braid. Smaller lines stretch more for a given load. So does 3-strand over double-braid, over parallel-strand.

So... the approach I've taken for my own boat is to use a good dacron (or you could use single-braid spectra, such as Samson AmSteel) pennant from the cleat through the chock, and then go with 2 lines out of that -- one very stretchy (for the "rubber band" effect), and one a little longer and more stout to overcome larger loading. Works well. Minimal chafe, easy motion, and secure tie-up at the dock.

For anchoring a bigger boat, I like chain, with a nylon snubber line at the boat end. For a small boat, in smooth/soft bottom conditions, the rode could be over 50% nylon spliced to a generous amount of chain at the anchor. A catamaran would call for a bridle to "connect" both bows together, distributing the load, and helping to keep the bows to weather. For permanent moorings for monohulls, we also use a bridle. In any of the scenarios, you get the same effect -- stretchy initially, and yet very stout when severely loaded.
Good pun! Thanks for sharing your approach. That was a nice summary. What you're using sounds like a good sensible set-up. I have never tied up to a mooring, only dock and anchoring situations and that was all limited to an inland lake environment. I have never had to equip a boat for the conditions found in the coastal environment. On my Endeavour 32 I used 30' of chain attached to the anchor and 200' of 5/8" 3-strand nylon to complete the rode. This worked for all conditions I was likely to encounter while anchoring. When tied to the dock I used 5/8" 3-strand nylon for bow and stern lines and 1/2" 3-strand for 2 spring lines with 3 8" fenders. It seemed to work well even though some of the powerboaters said the spring lines were overkill since the hills around the area blocked the wind pretty well. I used them anyway because it got a little gusty there a few times and I could feel the boat surge against the stern line on several occasions.
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Re: Polyester sling for chafe control

Rule of thumb, don't ever anchor from the stern.
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Re: Polyester sling for chafe control

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Rule of thumb, don't ever anchor from the stern.
I've never done that but I'll remember the advice. Is your comment in reference to setting 2 anchors and not tying one of them off at the stern but rather securing both at the bow? I think it was in the Pardey's book Storm Tactics" that I read about several anchoring methods in which they used 2 anchors. In one method they set 2 anchors off the bow at angles, 45* I think. In another they set 2 anchors in a line and tied off in the middle. I don't recall ever reading about anchoring from the stern except when using another anchor from the bow in a situation where you want to keep the boat oriented in a certain direction regardless of wind and current.
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Re: Polyester sling for chafe control

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I've never done that but I'll remember the advice. Is your comment in reference to setting 2 anchors and not tying one of them off at the stern but rather securing both at the bow? I think it was in the Pardey's book Storm Tactics" that I read about several anchoring methods in which they used 2 anchors. In one method they set 2 anchors off the bow at angles, 45* I think. In another they set 2 anchors in a line and tied off in the middle. I don't recall ever reading about anchoring from the stern except when using another anchor from the bow in a situation where you want to keep the boat oriented in a certain direction regardless of wind and current.
Only meant to let the boat swing allowing the bow to take the wind and waves. More important on some boats than others, but I don't think there are any weather situations warranting an anchor off the stern. That's all. Some debate two anchors off the bow, but I think there are times that will be an improvement. For example when you have to anchor in close quarters to limit swing movement.
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