Seasense Polypro anchor line. Am I Nuts?

[Knighthorse]

I realize this is anchor line. However, being round braid polypro had me thinking.

1/4" X 50' HOLLOW BRAID ANCHOR LINE
Economy anchor line for smaller boats. Made from 100% polypropylene fibers. Line floats and is rot proof. Plated steel snap-hook with large mouth to accommodate any anchor design.
Safe Working Load.....90 LBS.
Breaking Strength......850 LBS.
Probably not hammock do-able.

Then there's this one:

3/8" X 75' HOLLOW BRAID ANCHOR LINE

Economy anchor line for smaller boats. Made from 100% polypropylene fibers. Line floats and is rot proof. Plated steel snap-hook with large mouth to accommodate any anchor design.
Safe Working Load.....150 LBS.
Breaking Strength......1420 LBS.

Bigger diameter, yeah I know. But could this be usable for suspension lines? I see the Safe working load is 150, BUT break strength is 1420. How do they figure SWL being so far below breaking strength? Could I consider that as "lawyer speak"? Your thoughts please.

I've been using unrated braid "clothesline" on my diy at home and it is holding. Not sure if its nylon or what as the bag was tossed out a while ago.

Oh yeah www.seasense.com its under "Cordage" in the left column. Their dock lines are apparently nylon so probably wouldn't be a good choice.

[PuckerFactor]

I'm an arborist, and we generally use a 10:1 safety margin. Looks like they use a 9:1 or something. It's just to account for dynamic loading and knots and stuff.

Acer

[hangnout]

Clark hammocks use the polypro rope. The 1/4 is rated at about 1200 breaking strength and the 5/16 at 1710 breaking. The rope you are looking at is the economy version. It is easy to find the better polypro and it is still really cheap. Ace Hardware carries Wellington Brand Un-Manilla polypro. Clark used this in the past. It holds a knot better than the standard polypro and has the bonus of coming in a nice natural brown color.

[gargoyle]

I was just at walmart and saw the seasense rope, so I grab a 20' for $1.56. 3/8" hollow braid poly. I'll put my big butt on it tomorrow and let ya know. It was back by the boating stuff.

[Knighthorse]

Yup. Thats the stuff. Saw the "dock line" break strength and thought it might be do-able, but the "Double braid dock line" is listed as nylon. Sort of axed that idea.
Their dock line: 3/8" X 20' DOUBLE BRAID NYLON DOCKLINE BLACK
Give your boat a sharp well-kept look with premium pre-spliced double braid nylon dock lines. Both the cover and the core are manufactured from the highest quality marine grade nylon giving you the strongest and easiest to handle line. Whipped on the splice & bitter end.
Safe Working Load.....410 LBS.
Breaking Strength......3900 LBS.

Too bad its nylon. Pretty sure they use that for dock lines due to the stretch needed. Would this even be usable due to the stretch? (probably a dumb question since I think I know the answer already)

Hangnout: That Wellington Brand Un-Manilla polypro is the twisted type. I had the impression braided was a better choice. Was thinking about ease of splicing to the hammock, or rings possibly in place of larkshead knots. Maybe I'm nuts again. Their other poly braid looks good, but safety yellow, ick. Might have to drive to the ACE here and see what they have in stock. I'll put the un-manilla on the short list. Going to look around for green/brown poly braid. Might just give that up and go to webbing. That comes in most colors.

[Knighthorse]

Double posted whoopsie!!

[hangnout]

[QUOTE]Hangnout: That Wellington Brand Un-Manilla polypro is the twisted type./QUOTE]

Clark hammocks use the polypro twisted type. I think the polypro twisted has a higher breaking strength also.

[nacra533]

You can really use any sort of line, but each line type has different properties. "Stretchiness" is not a good one in this case.

Nylon in general is stretchy and easy on the hands. Dock lines and anchor lines are made to absorb shock, so they have to stretch some.

Polypro has stretch characteristics all over the map depending on weave. It can be much less stretchy than nylon, doesn't absorb much water, but does not tolerate the sun very well. UV is a factor for heavy outdoor use, but not really for hammocks. It's cheap. Ski rope is most often hollowbraid polypro. If you have seen someone wipe out on skis and watch the skirope come flying at the boat, you know it stretches a lot as well.

Lots of inexpensive, but decent general use lines have a polypro core, and sometimes polypro cover. It's fairly strong for its weight.

then there is MFP, multi filament polypro. I see it in lots of inexpensive outdoor lines, or at least they are camoflaged, but I have seen lots of stretch with it.

"Stretchiness" is a function of % loading and line length. Even with short line lengths, nylon and MFP stretch considerably.

If you want to go real inexpensive, you could use good ole fashion yellow 3 strand polypro rope and just know that you will have to account for the stretch when you hang it. It doesn't handle quick shock loading well at all.

[Rain Man]

I agree that 10-to-1 is a safe rule of thumb when human safety is involved.

You will notice on lots of web sites and packaging labels for ropes and lines a warning such as this:

"No For Use To Support Humans" or some such.

That's not lawyer talk (I am a lawyer), that is science talk by people who know some middle-school geometry and a bit of physics and are out to let the chips (and people?) fall where they may.

Rain Man

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