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davidpm 05-19-2015 07:28 PM

Knot failures
 
During fitting out the boat for school a couple of weeks ago I noticed two new ways to fail at knot tying.

The cleat hitch seems to be pretty full-proof but I managed to tie it in a way that let it slip off.

I was using a line that did not have a loop on the end so I had to use a cleat hitch on the boat side before it was tied off on the dock end.

What I did was hold the tail short and use the bulk of the line to make the cleat hitch.

What I should have done is to slack out a couple feet of tail and make the cleat hitch with the tail just like I would have to had done if the line was already attached to the dock.

It was only for a couple minutes and I did it on purpose in a hurry thinking it wouldn't matter.

It does, the line came off.

In another case I had a batten that has a hole in the end where the PO uses a cable time to stitch the batten to a grommet hole in the leach. I figured I could use some 1/8" line with a square knot. It would have worked but the square knot would not hold in the 1/8" slippery polyester line. We had to use the cable tie.


Add that to the fact that a clove hitch will not hold a 50" boat on a dock pole in Port Jefferson and I'm getting a collection of knot tying no-no's

I did have a success however. I was able to use a soft shackle I had with me to connect the halyard to the head of the mainsail to test it. The old shackle was too small.

This worked great until we got the replacement shackle.

desert rat 05-20-2015 12:05 AM

Re: Knot failures
 
David did the clove hitch fail immediately or take a while to work loose?

RainDog 05-20-2015 12:32 AM

Re: Knot failures
 
There are a lot of ways for a cleat hitch to fail. One thing we are taught early on is that it is sacrilege to tile a cleat hitch that is anything other than one wrap, one cross, and the hitch. This works great for most situations, but there are several where it will certainly fail. One is where the cleat is very large and the line very small. Another is where you have a smallish line on a cleat that is not a horn cleat. Both of these situations require more wraps before the hitch.

The key is to understand the dynamic of the knot: the hitch has to cause friction on the wrap. If one wrap is insufficient to provide friction, more wraps are required to provide enough friction.

There will always be the well meaning telling you that multiple wraps are un-seamanlike. Those who understand the mechanic of the know know better.

pdqaltair 05-20-2015 07:28 AM

Re: Knot failures
 
I never focused on knots until I started climbing. People ask "but how do you know the knot is good?" They are right, there is zero tolerance for mistakes. You check your work, every time.

I don't think I've ever had a knot fail, excluding a few mistakes with 6-pound mono when I forgot my glasses!

Clove hitches can slip on large diameter piles; the knot dynamic changes. Back it up by tying off the tail.

smurphny 05-20-2015 08:31 AM

Re: Knot failures
 
After losing a couple of battens overboard, I finally sewed deep, triangular pockets into my sails. Can't find a picture but they are triangular pieces at the leech into which the batten ends drop after sliding in. It's next to impossible for them to ever shake out and eliminates any tie-off system or hardware. Tying off batten ends is generally a bad system, prone to loosening and spitting out battens to the deep blue:-) +1 on more than one initial wrap on a cleat hitch if the cleat is a large one. Looking at the cleat hitches along docks everywhere, I've noticed that MOST of them are tied incorrectly.

knuterikt 05-20-2015 08:35 AM

Re: Knot failures
 
A square knot can easily collapse and get undone
From Square Knot (Reef Knot) | How to tie the Square Knot (Reef Knot) | Scouting Knots
Quote:

"There have probably been more lives lost as a result of using a Square Knot as a bend (to tie two ropes together) than from the failure of any other half dozen knots combined." (ABOK page 258). Never use it for critical loads.

davidpm 05-20-2015 12:55 PM

Re: Knot failures
 
Quote:

Originally Posted by pdqaltair (Post 2795865)
I never focused on knots until I started climbing. People ask "but how do you know the knot is good?" They are right, there is zero tolerance for mistakes. You check your work, every time.

I don't think I've ever had a knot fail, excluding a few mistakes with 6-pound mono when I forgot my glasses!

Clove hitches can slip on large diameter piles; the knot dynamic changes. Back it up by tying off the tail.

That's exactly what happened. It was a 10-12" piling.

davidpm 05-20-2015 12:56 PM

Re: Knot failures
 
Quote:

Originally Posted by desert rat (Post 2795609)
David did the clove hitch fail immediately or take a while to work loose?

It was a 50' boat and it was surging. It waited to fail at the worst possible time about 3 minutes after I tied it.

CalebD 05-20-2015 01:37 PM

Re: Knot failures
 
Quote:

Originally Posted by davidpm (Post 2796433)
It was a 50' boat and it was surging. It waited to fail at the worst possible time about 3 minutes after I tied it.

I thought I tied that clove hitch david. The wind was gusting up into the 40's. We also made a horn cleat go airborne from the dock that day. That was fun. Then the CG Aux. guys helped us resecure the 50' Bendytoe.

smurphny 05-20-2015 02:35 PM

Re: Knot failures
 
Quote:

Originally Posted by davidpm (Post 2796433)
It was a 50' boat and it was surging. It waited to fail at the worst possible time about 3 minutes after I tied it.

Adhering to Murphy's Law:-)


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