Replacing Standard Cable Lifelines with Dyneema Synthetic Lifelines on a Cruising Sailboat

We decided to replace our lifelines from the standard wire or cable lifelines (ours were coated in plastic) to Dyneema synthetic lifelines. I had already done several different projects that helped me learn how to splice Dyneema line, so this seemed like it would be a good option for us and fairly easy to apply.

On our boat, we have a mid-section of our lifelines that is stainless steel tubing so I needed to just replace the gate section on each side, and a longer section toward the bow on each side.

Measuring for the Dyneema You’ll Need

Our gate section, mirrored on each side, is 7-feet long and a straight shot (no stanchions or obstructions from start to finish). The forward section is 13.5 feet long and has a stanchion that the line has to pass through. Of course, you’ll need extra length on each end of every section for making your splices. So, on my project, I calculated that I needed a total length of about 108 feet. I wanted to give myself some extra room so I purchased 120 feet.

For the gate pieces, I calculated that I needed 13″ (bury) + 10″ (splice loop on one end) + 84″ (7-foot stretch) + 5″ (splice loop on thimble side) + 13″ (bury) = 125″ which is about 10 1/2 feet. So I need 4 lengths of that measurement as we have 2 lifelines on each side and a gate on each side of the boat. So that is 42 feet.

For the forward pieces, I calculated that I needed: 13″ (bury) + 10″ (splice loop on cow hitch side) + 162″ (13.5-foot stretch) + 5″ (splice loop on thimble side) + 13″ (bury) = 197″ which is about 16 1/2 feet. Again, times 4 = 66 feet.

Making and Installing Dyneema Lifelines with Stanchion

I spoke with several “seasoned” sailors about the project and had my plan in place. I would just need to splice a locking eye-splice into one end of the Dyneema line and cow hitch that around the stanchion or through the attachment point like below.

Cow Hitch Knot

Then, after threading the line through any stanchions, I would make another eye splice and insert a stainless steel thimble in order to protect the line as I passed a smaller diameter piece of Dyneema through several times to tension the lifeline and lash it in place.

Stainless Steel thimble for Dyneema splicing

So, before doing anything else, I measured the distances again to be sure I knew how much of a run I would need. For the forward section, 13.5 feet. Then I made my first splice. I used 1/4-inch Dyneema for this project. For the eye splice, I would need a bury length of 12.5 inches, which I rounded up to 13″. On the cow hitch end, which I was doing first, I wanted an inside loop of about 10 inches.

I’ll link at the bottom of this post to the YouTube video I used for making my Dyneema Brummel locking eye splice using only one end of the line.

Here’s the first splice.

Dyneema brummel locking eye splice

From that point, I needed to go up to and start working on-site. First, I detached the old lifelines and then cut them off with a cable cutter to remove them from through the stanchion.

Old rusty cable lifelines due for replacement

Forward attachment point for upper old rusty cable lifeline due for replacement

Using bolt or cable cutters to cut the old rusty lifelines off our sailboat during replacement

Once I had removed the old lifeline and cleaned up the connection points, I moved forward with attaching the new lifeline to the forward stanchion with a cow hitch knot. For the bottom lifeline, I wrapped the line all the way around the stanchion and used the connection point as a guide for where it needed to thread.

Dyneema lifeline cow hitch to forward stanchion

For the top, I just cow-hitched it through the attachment point.

cow hitch to top stanchion for replacing lifelines on our sailboat

Then, I passed them through the stanchion, measuring to where I wanted the splice and thimble to be (a good 6-8 inches from the attachment point on the other end to give plenty of room to stretch the lifeline tight before lashing) and remember to give yourself the extra room for the splice and bury.

Here you can see the 13″ marked on the line at the end for the bury, and the 5-inch section marked for the eye splice and thimble.

Measurements on Dyneema line for making a brummel locking eye splice

Once measured, go ahead and make your splice and insert the thimble.

Splicing a Brummel locking eye splice into Dyneema

Splicing a Brummel locking eye splice into Dyneema

Brummel locking eye splice with thimble in Dyneema line for synthetic lifelines

From that point, you need to prepare your lashing. For mine, I used a smaller Dyneema line that I already had here at the boat. I think it is 1/8-inch Dyneema.

First, attach one end of the lashing line to the lifeline at the thimble with a double figure 8 knot. See below.

First, tie a loose figure 8 knot in your line, near one end.

Double figure 8 knot attaching lashing line to Dyneema lifeline

Next, pass the tail through the thimble and then retrace the figure 8 knot backward through the knot.

Double figure 8 knot attaching lashing line to Dyneema lifeline

Double figure 8 knot attaching lashing line to Dyneema lifeline

Then, carefully tighten this up as much as you can.

Double figure 8 knot attaching lashing line to Dyneema lifeline

Now you’re ready to do your lashing. Wrap it around at least twice and pull it as tight as you can get it. When it is tight, finish the lashing with a bunch of half hitches.

Pulling the lifeline tight for your lashing

Dyneema lashing and a half hitch for tightening the synthetic lifelines

Dyneema lashing and a few half hitches for tightening the synthetic lifelines

Half hitches lashing the Dyneema lifelines to the sailboat stanchions

That wrapped up the first of the forward sections of Dyneema lifelines on our cruising sailboat. Doing the gate sections was a little different, in that I didn’t need to worry about a stanchion in the middle, but I did need to figure out how I was going to tension it, which could be with a lashing or could be integral to the clasp, depending on what type of clasp you use.

Installing Synthetic Dyneema Lifeline Gates

Measuring for my gates was a little more complicated because I was trying to get them to be the correct length to be tight without using a lashing section as a tensioner. Instead, I used the adjustability of the screw section of my ‘pelican hook’ gate hooks to be able to shorten or lengthen the run.

Pelican Hooks for the Lifeline Gates

You can see, on the image above, that the pelican hooks I used were the existing ones from the previous set of lifeline gates. (Hey, gotta save money anywhere you can when outfitting a cruising boat!) The problem I had, though, was that I needed an eye bolt or some way so that I would have an eye on the other end of the pelican hook so that I could cow hitch on the Dyneema lifeline gate.

I could have purchased new pelican hooks at the local chandlery that came premade with a loop on the end. These were $15 each though and I needed four strands of the gate sections … Thankfully, I brought my stepdad back into the equation, and we worked out a plan for him to weld some eye bolts onto the existing threaded piece.

Oh, I should also mention that I tried to find regular eye bolts to just thread into that pelican hook, but I couldn’t find any that fit because they are actually reverse threaded. Happily, my stepdad was able to just find some suitable parts and just weld them together.

So I started out by making an eye splice on one end of each of the four pieces of Dyneema that I was going to use for my gates. Be very careful at this step to make sure to do your calculations correctly and don’t cut your pieces too short! My gates are 7 feet long, so for each piece I made my first eye splice, then measured out 7 feet from the end of the splice loop, plus an extra 5 inches for the loop and plus another 13 inches for the splice bury. I added just a few extra inches on each piece so I wouldn’t be short.

two stretches of dyneema line spliced and cow hitched to the aft section of our lifeline gate opening

From there, I went up top and cow hitched those sections on and pulled them tight to mark where I would need the middle of the other end’s eye splice to lay.

Measure the length of the gate by hand

Above, I have the section pulled nice and tight so that I could try to see where I wanted the middle of that eye splice to lay.

Gauge where you want the eye splice

However! That is not truly where you want the center to be because you need to account for a few extra inches that will be taken up in the process of the cow hitch to attach it to the pelican hook.

Center of eye splice, plus 2 inches

So, above, my left index finger is pointing right to where the line actually bent back when I passed the line through the loop in the pelican hook. The bend in the line above, about an extra 2 inches, is where I decided I wanted the actual center of the next eye splice to lie. Once noted, I went back down below and made my next splices, giving myself 4 inches on each side of that center mark for the length of the splice loop, and then remember your extra 13 inches needed to bury the tail of the splice.

center of eye splice plus four on each side

Brummel locking eye splice in Dyneema line for our synthetic Lifeline gates

Once that was done, it was simply a matter of heading back up top and attaching the first section to the attachment point and then slipping the splice through the loop on the pelican hook, looping the splice loop back over the pelican hook so that it could be brought back around into a cow hitch on the pelican hook side.

pelican hook for lifeline gate cow hitched to new Dyneema lifeline gate section

Then, it is just a matter of adjusting the length of the screw/threaded section to ensure a nice snug fit of the gate. Note: the Dyneema lifelines will stretch out a bit over time (unless you get pre-stretched Dyneema), even so much so in just a couple days that I will need to go back and tighten the lashings back up and adjust the pelican hook settings in order to keep the lines as tight as we want them. So pay attention to that when planning your lifelines so that you will have enough room in them to go back and make them tighter.

Overall, I am SUPER happy with how these look and how they seem to have turned out. They look so much better than our old rusty cable lifelines and I trust the strength of the Dyneema.

Do you have questions on the process at all? Are you ready to replace your old cable lifelines with synthetic Dyneema!? If I can do it, so can you! Give it a go!! Feel free to shoot me a comment or a message on Facebook and I would be happy to help if I can!

Cheers!   ~Rachel

Dyneema lifeline gate on our sailboat


*Here’s a link to a YouTube video for the splice I used: Dyneema Brummel Lock-Splice with One Side Fixed

*And here’s a link to a YouTube video for the whole project: DIY Dyneema Lifelines by Tula’s Endless Summer

*We’re not associated with either of these videos in any way.

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