Failed Dockline

D

drbridge

New member
Yesterday my son and I cruised our C-Dory from Sequim Bay to Port Townsend area for some fishing. It was a great day to be on the water, but fishing was a bust. Around noon we decided to have some lunch and tied up to the Port Townsend City dock and walked in to town for a pizza. 45 minutes later we returned to find our boat hanging to the dock by only the line fastened to the mid ship cleat. amazingly the boat was fine and there was no damage. Upon inspection the factory spliced loop of the 4 month old dock line that was fastened to the rear cleat had pulled apart and left only the front line to hold the boat to the dock. I am assuming that a wake from the near by ferry landing bounced the boat off off the dock a few times while we were gone. I had left a fair amount of slack in the 1/2" line to allow for this.
I am very disappointed in this dock line (brand name "CORDCRAFT"). The scary part is we have been using the same type of line looped around our fore deck cleat to secure our boat to mooring buoys this summer while staying over night. Won't be doing that again.
We are looking for recommendations for a better quality dock line that can be relied upon.

Thanks

Doug & Susan
 
I only had hand-braided lines since '09 when we bought the boat. I just replaced out two, long bow lines with "Seadog" brand. The line itself is softer than what I had previously and the tightness of the individual stands (three strand) seems less "dense" (you'd agree if you could feel both, side by side). We'll see how long these last.
 
Whew, disaster averted. What a horrible feeling to look down and see a splice has come apart (and then thinking you have been mooring by one of the same ones all summer... :shock: Glad it gave you an "easy" second chance to fix the problem.

This isn't exactly what you requested, but I have always spliced my own lines. With three-strand it is especially easy, although I have spliced double braid as well (but only new line if it's double braid... I found out the hard way why they say that - it's difficult to splice "older/used" double braid).

I learned the first time by reading Brion Tosses book on rigging, etc. And I still refer to it if it has been awhile since the last time as I tend to not splice often enough to remember all the details.

For three-strand you don't need any special tools. Just the line and then some whipping twine to finish it off. All of my splices may not look perfect, but I know they aren't coming apart.

Side bonus is the lines are the exact length you want, the loops just the right size for your cleats, etc. And you can get fancy and color-code the whipping if you want to by buying colored whipping twine. Plus, maybe it's just me, but I get a great feeling of satisfaction looking at and handling lines I "made." Splicing them is fun because of this. And hey, a boat project with no dust or fumes! You don't get that every day :D

I use three-strand nylon for dock lines (Samson, New England, etc.), but others prefer double braid.

Sunbeam
 
I use both braided and 3 strand. Splices are far easier to verify with 3 strand, and the elasticity is better with 3 strand.

I second the advice to learn to do your own 3 strand splices. Easy to do, and a skill you can pass on to others.

Also with a braid splice, I sew thru the tail of the splice, and that is an extra security.
 
You think your good to go when you purchase line, this makes me think to always double check everything. I noticed some wear on dockline around piling have piece of garden hose cut to put on it next trip to stop chaffing.
 
thataway":2s0s75sz said:
Also with a braid splice, I sew thru the tail of the splice, and that is an extra security.
Click to expand...

I like to do that too (although it's usually three-strand). I call it "Insurance whipping" - maybe I got that term from Brion Toss, I can't remember.
 
I don't normally whip my 3 strands, except on some I will at the throat.

For the braid on braid, I will oversew the tail thru the outer layer of braid.
I also take a few stitches thru the area of the throat where the tail enters. I do this only after pulling hard on the loop. Often I will put the loop on a trailer hitch for a good pull manually and even give it a pull with the truck to be sure it is set well, then do the oversew.
 
cordova harbor has a lot of commercial boats in it, many jet drive and screws, requiring some speed to maneuver. Add to that a lot of people think little dinghys are exempt from "No Wake" rules. We get a lot of wind on occasion and the harbor is not very sheltered as well. The result is some wave action.

Thus, every line on my boat is doubled back to itself. I run the eye through a cleat, cleat to the dock, and then cleat back to the boat. This essentially provides TWO holding lines while only using one line. Any single part can fail (except a cleat) and the boat stays put. It's the only way I'm comfortable tying up.

I don't ever let any slack in my mooring lines either, I put my fenders out and tie my boat up tightly enough to compress them substantially. Leaving slack allows your boat to gain momentum before abruptly halted by a line drawn tight. If your lines have snubbers this won't be too bad, but otherwise, is a likely cause of your line failure.
 
I like the idea of "if you want it done right do it yourself". Right now I have way to much going on to need another project, so I found some Samson pro set twisted 3 strand nylon dock lines to replace the "Cordcraft" lines that I had the failure with.
I also like the idea of doubling back with the line to create a second tie. Might as well put that extra line to work. I will try this.

Thanks for the comments

Doug & Susan
 
Kushtaka":1oik325s said:
I don't ever let any slack in my mooring lines either, I put my fenders out and tie my boat up tightly enough to compress them substantially. Leaving slack allows your boat to gain momentum before abruptly halted by a line drawn tight. If your lines have snubbers this won't be too bad, but otherwise, is a likely cause of your line failure.
Click to expand...

One thing though: I don't think this would work in an area with tides and fixed docks (this occurs often on the east coast, for example). I have seen a number of boats "left hanging" by their lines when the tide drops. Either tied to docks or to pilings. (Maybe in your area the tides are so large that all docks are floating docks and no-one ties to pilings.)

With the tides-plus-fixed docks, long spring lines seem to work well (along with bow and stern lines).
 
Re: sunbeam's caution about tying off to a dock when there is significant tidal variation: permanent line arrangements here typically incorporate weighted bow and stern line terminations run through dockside pulleys, similar to a sash weight setup. Must be common. Bet someone will have a photo.
 
Sunbeam":3bicnvmu said:
(Maybe in your area the tides are so large that all docks are floating docks and no-one ties to pilings.)
Click to expand...

Yup. Huge tides. 20+ feet difference sometimes. The harbor docs are floating on pilings. Our fuel dock does not float, the ships that take hours to fuel need to retie several times.
 
Thanks for the reminder on this. We use commercially spices lines and I inspect them carefully before using them with confidence as I have about 20 years experience scrutinizing ropework which is better than nothing but still no guarantee. I will admit that when we kept Aurelia in the water fulltime, I did use simple knotted lines at the home dock for added piece of mind. Someday I will take the time to do some personal line splices for the boat but not quite yet.

http://www.c-brats.com/modules.php?set_ ... _photo.php

Greg
 
http://www.thefirestore.com/store/produ ... FPA-Rated/

I used a length of this static rope and for 7-8 years and it is really holding up nicely. The color has a dirty look to it after many seasons of fishing and water time but it provides me with great confidence that it will not fall apart.

A other source may be a REI store that sells climbing rope by the foot. These ropes are built by guys who give a dammed about a load and durability.

I also had a crapper of a dock line experience.

Just an idea

Good Hunting!

Chris
 
I have always been told to stay clear of climbing ropes for primary marine use. I am sure that they can be useful in many situations. I don't have a lot of knowledge about climbing ropes, and have only used them on a very few occasions. But they do not splice well. (But can hold a knot well). I believe that there are basically two types--the static, with little stretch, and the dynamic--which has a lot of stretch. Both are cored ropes. I believe that many climbing ropes are stranded core, rather than braided core. (Although there are some braid on braid).

I have just felt that marine ropes have the specific quality which is good for boating, and climbing ropes for mountaineering…..

I believe that the marine ropes (at discount places--including Defender for Sampson Ropes) are cheaper than REI for climbing ropes of comparable size and strength.
 
I used kernmantle climbing ropes for rock and glacier work, for which they are ideal. None of these were static lines. However, the kernmantle ropes have fsr too much stretch under load for use as docklines, etc. I agree with Bob's summary.

Stick to ropee designed for marine use.
 
I don't know why this is exactly (I don't use climbing ropes for boat applications), but don't climbers replace the stretchy ropes after a fall? If so, that might mean that they are nicely stretchy, but something about the way they stretch weakens them for future use - sort of like a foam bike helmet that you replace after one crash.

I'm also not sure how resistant they are to UV on a longer term basis.

I do use the "non-stretchy" climbing type rope for things like tying kayaks onto the car, but for the boat I use Samson, New England Ropes, Yale, etc.

That's not to say no-one should think outside the box, but for myself I'd have to do more research and understand more about climbing ropes before using them for dock lines (but instead I'll just stick with the line I already use).
 
Climbing ropes (cored) can have issues with abraision in salt water where they get wet and dry out repeatedly. The crystalized salt chafes the line from within pretty quickly.

It also works poorly in silty water.
 
Sunbeam":1k9n1fsp said:
I don't know why this is exactly (I don't use climbing ropes for boat applications), but don't climbers replace the stretchy ropes after a fall? If so, that might mean that they are nicely stretchy, but something about the way they stretch weakens them for future use - sort of like a foam bike helmet that you replace after one crash.

I'm also not sure how resistant they are to UV on a longer term basis.
Click to expand...
This is OT, but it may help illustrate why climbing ropes are not well suited for marine use. In brief, yes, the rope is weakened with each fall, but not usually after just one fall.

Climbing ropes are rated by the number of leader falls they can sustain under controlled testing. A leader fall typically might involve a 20 ft distance above an anchor or belayer, which translates to twice that distance before the rope begins to take the weight of the falling climber. With each fall, the rope loses some of its elasticity and ability to absorb energy. The latter is better than what happens with a so called static rope, which does not absorb much of the energy of the fall. In lieu, the climber's body does, with more damage to tissues, bones, perhaps organs.

But, the rope is damaged slightly with each fall, so that its energy absorbing ability diminishes each time. So that climbers retire a rope after the rated number of leader falls, ideally.

In marine use, you would have to track the number of times the rope was stressed to a "leader fall" limit, and retire the rope when it had reached its rated limit. Pretty impractical.

I'll leave open to others how you might know when to retire a mooring line which has seen a lot of use.
 
Anyone looking for descriptions of how climbing ropes are rated and tested may find parts of this useful. http://www.alpineexposures.com/pages/fa ... -test-uiaa

It has been decades since I climbed anything, or handled a climbing rope. The testing is much more sophisticated than I remember. Modern climbing ropes typically are rated to handle 5 falls by the UIAA. In my day we retired a rope after two leader falls, and I believe ropes ran to a three fall rating. My son climbed very aggressively for 20 years or so, and I believe he found that his ropes were retired because of abrasion of the exterior sheath well before reaching the leader fall limits.

Reading the link above made me wonder how mooring lines are tested.

There are several videos on YouTube showing the UIAA testing procedures, which include to failure for maximim load. Probably you don't want to dwell to much on those!
 
Back
Top