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Tracyandkimo · 18-11-2020, 06:18

Looking to make up some jack lines. I had planned on using 1" nylon webbing from sailrite. I was leaning towards the one w/an average breaking strength of 2,200 lbs.
Also, my plan was one line for each hull (it's a cat) from stern to bow and then a transverse line from port to starboard on the forward deck/Trampoline.
Thoughts?

**Pete7** · 18-11-2020, 06:40

We discussed jack lines about 18 months ago, perhaps a bit longer.

The discussion was aimed at mono hulls, but worth a search. The upshot was the lines should if possible run across the cabin top so if you fall you don't go over the life lines. This as apposed to running the lines along each side of the deck. there were some good points raised about being able to clip on before leaving the saloon and before leaving the cockpit to go forward. Not easy to arrange, but potentially worth it to keep the crew on board.

Pete

**Tupaia** · 18-11-2020, 06:50

As you are suggesting but it is worth terminating the side lines on the forward beam half way between the centre line and the bows. This gives access to the furler and the bow cleats

thinwater · 18-11-2020, 07:12

a. Jackline is one word. A jack line is a utility line, often seen on traditional sail luffs.

b. Search the topic. The required strength is 4500 pounds, including splices, due to the significant tight rope effect and as allowance for deterioration. The World Sailing Offshore Rule is the source.

c. In general, nylon stretches too far. Polyester webbing is the standard. Dyneema is another option.

d. For a cat two line is fine, but you can run them considerably inboard of the hulls toward the bows and still reach everything. A transverse line should only be needed on really fast cats where stuffing a bow is a risk. Another option is a longer than normal second leg on the tether. End the jacklines well short of the front beam; you don't want to go over the beam!! Don't use the cleats for anchor points; they are the wrong places on most boats, but even more so on cats.

Search jacklines on my blog. There is some cat specific stuff.

http://sail-delmarva.blogspot.com/20...hulls-and.html

Snore · 18-11-2020, 07:39

Quote:

Originally Posted by Tracyandkimo

Looking to make up some jack lines. I had planned on using 1" nylon webbing from sailrite. I was leaning towards the one w/an average breaking strength of 2,200 lbs.
Also, my plan was one line for each hull (it's a cat) from stern to bow and then a transverse line from port to starboard on the forward deck/Trampoline.
Thoughts?

2,200 is too light. There are things to skimp on and things not to skimp on. Safety gear is the latter.

A 6,000 pound, double walled webbing is the only way to go. The double wall will allow you to see chafe beginning to occur, and still have a safety factor.

On catamaran deliveries I run two jacklines on the coach roof, or use the deck mounted halyards on one side and then a separate one from the mast to the center of the bow. If I ever had a need to go from the center to the outside end I would clip onto the seagull striker.

In my opinion, jacklines should NEVER be run along the edge of the boat. If the goal of the jackline and tether is to keep you on the boat- why set the jackline close to the edge?

WestMarine is often trashed on this forum. But IMHO, they have the best jackline and the tether they sold was do good, it was copied by another firm.

Tomodore · 18-11-2020, 08:33

Agree that nylon is a poor choice the stretch that makes it a good choice for anchor snubber makes it a poor choice for jackline. The Mexican patrol boats here have no lifeline but have a track similar to a genoa block track. the sailors clip into a car and move it along the track and then they can’t slide back as we would with a traditional jackline The track is mounted on the deckhouse about 4 foot off the deck

Tracyandkimo · 24-11-2020, 06:51

Thinwater,
Thanks for the info. In a cursory search, even the double walled tubular Polyester has a much lower breaking strength than does Nylon. What size are you typically using? As a reference, 1" tubular Poly from Sailrite has a breaking strength of 2,700lbs while the 1" nylon is 4,700lbs. Thanks again!

thinwater · 24-11-2020, 07:19

Quote:

Originally Posted by Tracyandkimo

Thinwater,
Thanks for the info. In a cursory search, even the double walled tubular Polyester has a much lower breaking strength than does Nylon. What size are you typically using? As a reference, 1" tubular Poly from Sailrite has a breaking strength of 2,700lbs while the 1" nylon is 4,700lbs. Thanks again!

It does NOT need to be tubular webbing. You should be able to find strong enough webbing. But I wouldn't use webbing on a cat.

The big problem is sewing the ends. It is VERY hard to sew webbing to full strength. One suggestion to DIYs is to splice them from Amsteel and then run then inside webbing just for protection and so that they do not roll underfoot. Better yet, on a large cat, do as I did and run them along the cabin sides so they are not underfoot. Then just use 1/2-inch rope and they will be very strong and will stand the sun better than webbing, allowing them to be left rigged for years.

They are attached to bolt hangers, not cleats. This keeps them inboard and away from the bow.

I'm not big on Sailrite for safety gear information. For example, there is almost nothing right with this picture from their web site.

The harness fit is comically poor, none of the the tether clips meet any standard, and I doubt the harness, tether, or jacklines do.

The companion photo shows the jacklines secured with two half hitches, which is not a webbing knot, may slip, and probably weakens it 50% (and the webbing is probably marginal strength to start with).

Thumbs Up · 24-11-2020, 10:57

I run mine from the aft cleats to the mast. I tie them to the base of the mast with a bowline. I use polyester webbing.

Sailing Ohm · 24-11-2020, 14:07

Just replaced our jacklines with slack line webbing from Balance community. It’s apparently being used in some race boats and well exceeds weight requirements. Salesperson from balance community was very familiar with jacklines and their needed requirements. Also a fraction of a cost of commercial marketed marine jacklines.

https://www.balancecommunity.com/products/mantra-mk4

I run ours from bow cleat then back to cleats behind winches. This allows for easy ability to walk from for to aft without unclipping and switching lines at the mast.
I’ve added a dedicated dyneema loop at the mast to clip into if extended mast work is needed.
Each person has a 6’ tether and I have a 6’ and 3’.