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Old 07-22-2017, 10:34 AM   #1
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What is the strongest 1" line for dock tie up ?

I ask as during hurricane Matthew, which was only category one with winds up to 60 mph, the boat got away as most of the 1" lines broke, and best I could tell not due to chafing...just flat out tension. No idea what the lines were exactly as they came with the boat... "soft " texture and black in color if that means anything.

So, what 1 inch line would be the least likely to break from stretch tension ?
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Old 07-22-2017, 10:41 AM   #2
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Amsteel, but really need chafe protection.
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Old 07-22-2017, 10:51 AM   #3
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I just use three braid nylon. I found out that the black lines seem to age out from UV exposure. Busted one pulling a stump with my truck, NO WAY was it anywhere near its limit. Nylon seems less susceptible to UV. Also like the stretch as that limits stress in the line.
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Old 07-22-2017, 10:52 AM   #4
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I seriously doubt if 1" nylon which is used for dock lines actually broke without first chafing. 1" has a minimum breaking strength of about 20,000 lbs. That will lift a lot of boats out of the water vertically. With four 1" lines on the corners of the boat, the piles or the cleats would give way first.

Chafe was probably the biggest factor.

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Old 07-22-2017, 11:03 AM   #5
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Really surprised they broke. Can you provide more info on where and how they broke? At a cleat? at a thimble? in the middle?
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Old 07-22-2017, 11:17 AM   #6
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I seriously doubt if 1" nylon which is used for dock lines actually broke without first chafing. 1" has a minimum breaking strength of about 20,000 lbs. That will lift a lot of boats out of the water vertically. With four 1" lines on the corners of the boat, the piles or the cleats would give way first.

Chafe was probably the biggest factor.

David


Agreed. Unless the lines were seriously degraded by age I would they would break just from the load.
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Old 07-22-2017, 11:20 AM   #7
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In a storm, with a lot of boat motion the lines can really "snatch" violently. That's where a little stretch helps. The black ones have very little stretch.
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Old 07-22-2017, 11:39 AM   #8
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Originally Posted by Ski in NC View Post
In a storm, with a lot of boat motion the lines can really "snatch" violently. That's where a little stretch helps. The black ones have very little stretch.
That must be it as they broke pretty much in the middle..I was amazed as well.....no chafing involved.....unless there was some previous chafe damage I didn't notice.
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Old 07-22-2017, 12:23 PM   #9
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I am a fan of three strand nylon for permanent dock lines. They are strong, stretch, and easy to splice to the length you need. 3 strand is also relatively inexpensive so you can replace them easily after a few years if you see wear.
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Old 07-22-2017, 12:40 PM   #10
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First, double up for storm lines. The first line should slow the boat as the line stretches, the second should stop the boat with only minor stretching. Repeated shock loading destroys a rope internally. In rock climbing, they use to (may still) rate ropes for number of falls. After so many falls (shock loads), the rope is retired.

Second, avoid short rope runs between dock and boat. The velocity at which the boat stops (a contradiction of terms), hugely impacts rope degradation. You want to slow the boat to a gradual stop, not jerk to an abrupt hault. Shock loading destroys the cords and can break loose boat hardware.

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Old 07-22-2017, 01:20 PM   #11
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Amsteel, but really need chafe protection.
Yes, with a breaking strength of around 100,000 pounds, one inch Amsteel is probably the winner by a lot!
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Old 07-22-2017, 01:53 PM   #12
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No stretch in amsteel....use it for chafe but beeter have someting for stretch.

Might as well use wire to tie thr boat up with.
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Old 07-22-2017, 01:56 PM   #13
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I am a big fan of Amsteel but would not use it for mooring lines as it has no stretch what so ever. Maybe use it as a back up to a nylon line, tied a little longer, so it doesn't come into play until the nylon is stretched out.
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Old 07-22-2017, 02:04 PM   #14
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No stretch in amsteel....use it for chafe but beeter have someting for stretch.

Might as well use wire to tie thr boat up with.
Agreed.

But, it is the correct answer to the OP's question.
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Old 07-22-2017, 02:09 PM   #15
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Originally Posted by Ski in NC View Post
In a storm, with a lot of boat motion the lines can really "snatch" violently. That's where a little stretch helps. The black ones have very little stretch.

Never heard color can affect stretch, before. The New England Ropes charts usually show that colors can matter (white and gold/white being "stronger" than other colors), but I don't remember anything about colors and stretch...

??

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Old 07-22-2017, 02:44 PM   #16
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Never heard color can affect stretch, before. The New England Ropes charts usually show that colors can matter (white and gold/white being "stronger" than other colors), but I don't remember anything about colors and stretch...

??

-Chris
I'm being very generic with the color. Not sure of a better description, but the super common black dock lines usually sold pre-made.
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Old 07-22-2017, 03:00 PM   #17
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...1" has a minimum breaking strength of about 20,000 lbs...
They test strength when dry. Wet nylon rope can lose up to 25% of its rated breaking strength...add in cyclic loading (which further weakens it) and a heaving boat...
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Old 07-22-2017, 03:04 PM   #18
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Quote:
Originally Posted by Ski in NC View Post
I'm being very generic with the color. Not sure of a better description, but the super common black dock lines usually sold pre-made.

Ah, fair enough. We have some black 3/4" Samson double-braid lines and I don't they've ever stretched much. Stiff as a board, usually, even when new, even after washing, etc.

OTOH, the 5/8" black double braid NER lines have always been much more pliable, much easier to stretch as necessary...

Difference in thickness, of course... Both pre-made, though.... I'd guess maybe not so much the color but the brand, the way they're laid, etc...

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Old 07-22-2017, 08:58 PM   #19
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8 Strand Plaited Nylon Line is one of the best for strength, shock and takes less space to store. Check out the picture. 100' of three strand on left and 100' of Plaited line on right.
Click image for larger version

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Old 07-22-2017, 09:20 PM   #20
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Well there have been some very interesting comments here about lines braking in the middle while under load. I have never see that and am interested to know if anyone can provide any more input as to how and why. 50+ years in boatyards and marinas i have seen a lot of dock lines fail in storms. But it was always at a chafe point. What am I missing? also amsteel has no stretch, zero, nada, and in rough conditions the entire shock load is directly applied to the points of attachment. A very strong rope, but might very well break the cleat at one end or the other.
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