New Dock Lines versus Older Dock Lines

[Rasselas36]

During Hurricane IRMA I secured my boat with both new 5/8" 3-strand lines and older 5/8" 3-strand lines. The new lines were purchased from WM during one of their sales this year. I had planned to use them on an upcoming cruise we were taking in October. I doubled up all lines from my cleats and the dock cleats. After IRMA passed I returned to my boat I found that 5 of the 6 new lines had broken and only 1 of the older lines had broken. The lines were not mixed in other words new lines were secured together and older used lines were secured together. A surveyor told me that new lines are like new shoes and should be used so they can stretch before using them for a storm, especially a hurricane. Would be interested in your experiences/comments.

 

[Charlie Jones s/v Tehani]

sounds reasonable to me. During Harvey I had 3 lines snap- all about a foot away from the boat. One was brand new, but tied along with an older line strongly suspect shock loads did it. We had a 7 foot storm surge and 3 foot seas in marina. I think some of the rubber snubbers you wrap the line around will be on my sopping list

 

[jssailem]

Nylon line has up to 20% stretch. This is good for a dock line but in a storm which is generating lots of force and movement the line while stretching is generating a lot of internal heat. As the strands heat up they are being stressed. In your case stressed till they broke.

It is impossible to tell if the breaks was due to the new lines. The new lines may have born most of the stress and broke. If the old lines had been in the same place they may have broken more quickly.

Also impossible to assure that the old and new lines were of equal fiber quality.

Way too many variables to reach a meaningful conclusion.

As a future idea perhaps a larger sized line may be of use in similar conditons.

 

[Brian D]

Personally it this day and age with the wherewithall of high tech products, the lines should not have broken unless the size did not match the weight they were designed for. In otherwords, I think what that surveyor said was a lame excuse. So if you buy new lines you are suppose to stretch them before using them? Ha! Sorry but that just does not sit well with me.

 

[LakeOntario270]

3 strand lines are crap compared to braided line. When I got my first boat, a 24 footer, I used 1/2" 3 strand and I broke several during storms. I switched to braided and have never broken any. My theory is 1 stand takes more load than the other 2 and will then break. You now have lost 1/3 rd of the strength. Process then repeats.

 

[capta]

3 strand lines are crap compared to braided line. When I got my first boat, a 24 footer, I used 1/2" 3 strand and I broke several during storms. I switched to braided and have never broken any. My theory is 1 stand takes more load than the other 2 and will then break. You now have lost 1/3 rd of the strength. Process then repeats.

The SWL of a quality line, be it three strand or braid, is the SWL. There is no reason to think three strand will part before the equivalent braid.
Personally, I prefer three strand nylon for dock lines because it is easily inspected, cheaper (I'll replace sooner), and easier to splice. All my braided line aboard is Dacron and all the three strand is nylon. That makes it really easy to use the proper line for a task.

 

[jssailem]

Perhaps looking at this chart will help guide your selections of line material.

http://www.boatsafe.com/marlinespike/safeload.htm​

The safe working load of 3 strand and Single braid Nylon is the same. Interestingly when you get above 5/8ths the nylon line has a higher breaking strength than either Dacron or Polypropylene.
We are led to assume that "LakeOntario270" meant nylon double braided line because Dacron double braid (which we use everywhere on boats) has a lower breaking strength then Nylon double braided.
But of course double braided line is more expensive than 3 strand, so perhaps spending more money is better than buying 3 strand at a larger size.
Many variables to consider.

 

[jviss]

The only reason I don't like nice, braided dock lines is that splinters on the dock will cause "pulls" in the cover. Three-strand is rugged stuff, oh, and much easier and quicker to splice an eye into an end.

 

[heritage]

Shock-loading of the lines can be mitigated somewhat by increasing the lengths of the lines. Such as,,, run the bow cleat line to the middle cleat on the dock and run the aft cleat line to the same middle cleat. Run your mid-ship lines to the forward and aft dock cleats. In other words, if possible, avoid short runs of lines to dock cleats during a storm with high waves.

 

[jibes138]

How about some pictures of the failed lines? Was chafe a factor?

 

[JamesG161]

I would suggest you can not conclude anything about lines snapping/breaking in a storm.

Why not?
1) Wind directional change
2) Wave height and frequency.
3) Mass of the boat and shape factors.
4) Slack in lines
5) Number of lines and angle of lines to the load applied.
6) Interaction with of all boats around you.
7) Two lines together doesn't not mean double the SWL.

Boring? I thought Engineering Dynamics was boring.
Jim..

 

[shemandr]

What I like to do for storm prep is to use a combo of 3 strand nylon and braided dacron. I tie the dacron a bit longer than the nylon. What I imagine this does is to use the stretch property of the nylon to dampen the hard stop of the dacron. I also try to take my boat to a safe location if I think it's going to see south or south east wind. In the recent case of Jose here on LI, the storm was predicted to and did pass to the east. That means my boat saw primarily north and northeast wind. I tied some extra lines to the transom and mid-ship cleats and went off to VA and slept like a baby. The fetch to the north is almost 3 feet.

 

[jviss]

There are so many variables that one may never know why those new lines broke, and the old ones didn't. One thing that occurs to me is that the new lines may have been "new old stock," and dried out, as nylon will do. Then it loses a lot of tensile strength, even becomes brittle. You want relatively new nylon rope. I've heard three or five years is "it" for service life.

It would be interesting to get a sample of the "new" three-strand and test the tensile strength. My son has access to those big tensile testers for metal, maybe, ....

 

[Ward H]

Couldn't there just be a difference in the quality of the new line vs old line? I've noticed a different feel and stiffness in pre-made 3 strand dock lines from WM and Samson 3 strand dock line bought by the foot from another supplier. The WM line seemed lighter, softer and much more limp than the Samson line.

 

[jssailem]

Ward I think your on a good track. Quality can be different as not all lines are create the same. The consumer needs to look at the line data SWL when they buy product.
James listing of variables are a good start as well as identifying the boredom that often overwhelms folks that would just like to untie the lines and go sailing.
The issue I looked at, is the Original Poster was frustrated that some lines (new ones) broke and some did not (old lines). When talking to a surveyor he got a response that blamed a lack of conditioning the "new lines" by the owner.
I say that the statements were opinion not supported by facts. Several good ideas are here suggested if you want to do a forensic like investigation.
Or maybe get some bigger lines, check with others as to how to secure your boat for the conditions, and go sailing.

 

[pateco]

I bought 200' of 3 strand nylon online before Irma. However, due to the continuing effects of Murphy's law, It arrive after the storm. I have yet to cut and splice it, but it does feel much softer in the hand than the comparable line I already had.

3/4"x200' Nylon Anchor Boat Rope Twisted Three Strand 12592LB w/ Thimble $52.20

 

[jviss]

I bought 200' of 3 strand nylon online before Irma. However, due to the continuing effects of Murphy's law, It arrive after the storm. I have yet to cut and splice it, but it does feel much softer in the hand than the comparable line I already had.

3/4"x200' Nylon Anchor Boat Rope Twisted Three Strand 12592LB w/ Thimble $52.20

View attachment 141336

No brand name, probably cheap Chinese stuff. I would never buy rope that's not traceable to a manufacturer.

 

[jssailem]

That Murphy guy is everywhere.
Chip are you comparing new and new line? A soft hand is not necessarily bad. It may be the tightness of the line twists. I bought a set of pretty RWB lines from WM that were 'soft hand' and use them when I visit marinas and want to dress up the boat. I have some everyday duty lines that are white and stiffer. I know the SWL numbers on each an use them based on service conditions.
It is just a guess, but 3/4 nylon line should secure your H31 with out much trouble. May have a bit of issue on the H31 cleats or deck chaulks.

 

[pateco]

That Murphy guy is everywhere.
Chip are you comparing new and new line? A soft hand is not necessarily bad. It may be the tightness of the line twists. I bought a set of pretty RWB lines from WM that were 'soft hand' and use them when I visit marinas and want to dress up the boat. I have some everyday duty lines that are white and stiffer. I know the SWL numbers on each an use them based on service conditions.
It is just a guess, but 3/4 nylon line should secure your H31 with out much trouble. May have a bit of issue on the H31 cleats or deck chaulks.

Comparing the new E-bay line and older but rarely used line. I only use the 3/4 for Hurricane tie out. The existing line I had is much stiffer/tighter, than the E-bay line.

3/4" works fine on my cleats, but does not allow me to double up. I used an eye spliced 1/2" loop first, and then cleated the 3/4 on top of it. so that I had 3/4" and 1/2" doubled up lines.

 

[Ron20324]

The OP says the line was from West... was it a brand name, or as someone pointed out about not buying a known name when you are betting you boat on the line's quality. I don't disagree/disagree with the surveyor's opinion, but it does seem a decent cause. I'm sure there are scads of line bought just before storms, but can you put the failure on the line, or it's use in the storm. Sounds like an MS post is need?