Dyneema Lifelines

[brian.webb]

Hello PDQ'ers.

My lifelines were rusty and old. The vinyl coating was deteriorating, and I cut myself a few times on some wires that were sticking out. I replaced them all with Dyneema and they look great. Thought I'd share what I did. Before and after pics attached.

Dyneema is super strong, approaching the tensile strength of steel. Creating an eye in the line reduces the strength by about 10-20%, so these are likely the strongest component of my lifeline system.

I wanted white Dyneema. White is the original no-color version of Dyneema. Everything non-white is dyed. I used red Dyneema for my dinghy and the color has rubbed off on parts of the dinghy where it touches. 1/4" fits through our stanchion post hole. Fisheries Supply sells 1/4" white Dyneema: https://www.fisheriessupply.com/samson- ... 16-006-030

Eyes can be spliced in 12 strand Dyneema in two different ways. Locking (requires both ends of the line) and non-locking (only need one end of the line). I was able to use a locking splice on all ends except the long lifelines port and starboard that run through the hole in the stanchion. For these two I used a locking splice aft and a non-locking splice forward.

How to splice can be found here on Splicing Guru's YouTube channel.
Locking eye splice
https://www.youtube.com/watch?v=sp85pjb2BtU
Non-locking eye splice
https://www.youtube.com/watch?v=co1nqFfb7Ps

Some notes on his video:

• Note that he calls both eye splices "locking", where as I like to differentiate because non-locking requires sewing up the tapered end to lock it.
• I recommend you get the fid that he uses.
• Since the lifeline has very small tight eyes I didn't mark both ends, just the midpoint/end.
• He doesn't mention it, but the second pass through on the line is much cleaner if you pass through about 1/4" away from the first pass through. I have a few ends where I passed through about 1/2" away and you can see the separate line a tiny bit (just me being picky).
• I didn't make dark marks with the marker pen like he does. Just a tiny dot.
• Because some of the removable lifelines are very short, for these I couldn't use the full 12" (50 diameters) for the taper. I found about 6" worked fine. This does reduce the strength but I figured lifelines only need about 200-300lbs of force so it's likely still 10x stronger than what it needs.

REMOVABLE LIFELINES
There are 11 locations on my boat that have removable lifelines for access. 4 on the bow, 6 aft, and one on the flybridge at the top of the stairs. For one end I used D shackles so that the end of the line won't float around on the shackle and stay on one end.
https://www.amazon.com/gp/product/B071Y57Y8H

For the other end I used a threaded stud with a splice eye that screws into the pelican hooks. This threaded stud was difficult to feed through the line for the locking splice, but it does work. All of my pelican hooks, with the exception of one, have a left hand thread. Your boat might have different hardware than mine.
https://www.fisheriessupply.com/johnson ... stud/20-63

For the spring-loaded pull out on the pelican hook I also bought these nifty little lanyards (the 2" one)
https://www.fisheriessupply.com/ronstan ... rd/rf6093s

PERMANENT LIFELINES
There are 6 permanent lifelines (no pelican hook) on my boat. For these I used a jaw toggle with splice eye on one end and a turnbuckle with a splice eye on the other end. NOTE: Extend the turnbuckles out as far as practical and make the line as taught as you can. When the splice is done and installed, tighten the turnbuckle and grab each line towards each end and shake it with a lot of force. This will pull the slack out of the tapered end, allowing you to tighten the turnbuckle further (not too much tension though).
https://www.fisheriessupply.com/johnson ... al/ls-3600
https://www.fisheriessupply.com/johnson ... le/ls-2900

Credits: This was in large part inspired by Russ on Twin Sisters (https://esc-pod.com/) but I've added a few twists (pun intended) to his method.

BEFORE AND AFTER PICS

[PDQfan]

Nice work Brian! Thanks for the detail.

[deising]

Nice work, Brian. When you stated " I figured lifelines only need about 200-300lbs of force," that is not correct.

If a rope (or wire, etc,) is taut between two rigid attachment points and you exert a perpendicular force, say at the middle, the tension in the rope will be many times higher than the applied load. A 200 pound person falling against a lifeline will exert a dynamic load, which is higher than static, and you could easily see 1,000 pounds or more of tensile force in the rope.

3/16 inch coated lifeline wire is typically rated at 3,700 pounds of breaking strength. Dyneema is incredibly strong, too, so a proper size rope and splice works fine. Good luck.

[brian.webb]

Thanks Duane. Yes, you're correct. The 200 lbs is a design load that I borrowed from OSHA requirements for construction sites for guardrail systems. That is the design load, so the actual load you're correct is significantly higher, had it backwards. My thinking is that the Dyneema is stronger than what was there before. And on second thought now, the connection hardware is probably the weak link in the lines.

Brian

[Ortolan]

Brian,

Lookin’ good - Great job!

Splicing Dyneema seems daunting at first, but after a few tries is actually easier than 3-strand, etc. Looks better too, as the ends end up inside the braid.