Joining two long tow lines - how to do it ?

[dom]

Re: Joining long two lines - how to do it ?

I would use a carrick bend, which according to Ashley is one of the strongest bends available, and is specifically recommended for joining anchor warps. It is also very easy to undo while remaining secure. There are two ways of using it; one is to tie the knot and leave the ends free; on taking a tension the knot will collapse into it's stable form with a long bight at each end of the knot; pushing those sideways will open the knot. The other is to seize the ends to the standing parts so it remains in the under-over pattern used to tie it ; this is what Ashley recommends for anchor warps. If in a hurry I would use the former; both are very secure and very strong.

I agree, though part of the attraction of the so-called pretzel knot is its physical suitability for large diameter ropes.

 

[TLouth7]

Re: Joining long two lines - how to do it ?

I would probably use a sheet bend, because compared to the more exotic bends I would be more confident that I had tied it correctly. The Zeppelin bend (how have I never heard of it before?) does look really good though.

Additionally you will need to join your tow-rope to a bridle on the yacht. Conventionally this would be a bowline through a fixed loop in the bridle, but given that we all seem to be avoiding joined loops (because of chafe) is there a better way? I could imagine tying a double sheet bend, with the bridle loop as the bight (blue line in image in post #7), but this wouldn't work if the tow-rope is thicker than the bridle.

 

[johnalison]

Re: Joining long two lines - how to do it ?

I agree with double sheet bend but the photograph above gives the wrong idea IMO - the tails seem minimally short.

I would tie the knot with long tails and seize or cable tie each tail to the standing part.

I use sheet bends for most purposes but for a tow I might use bowlines. Even with a bowline, I would normally half-hitch the tail for extra security.

 

[JimC]

Re: Joining long two lines - how to do it ?

The Zeppelin bend (how have I never heard of it before?) does look really good though.

It is a very good knot, I personally prefer it to the carrick bend as it draws tight in a predictable way without slipping along the tails, is even easier to untie after being loaded, and will hold securely even if you haven't had time to fully tighten it, it will even hold when you can see daylight through it.

To tie it make a figure 6 in one rope with the tail towards you, Tie a figure 9 in the other rope with the tail away from you. put the 6 over the 9, pull the tails through and pull tight.

https://www.youtube.com/watch?v=h3cDYhN5vk4

 

[cueball]

Re: Joining long two lines - how to do it ?

Slight thread drift, but do many people carry a dedicated towing line? We took a tow from a very obliging Dutchman a few years ago when we got a ball of rope around our prop off Calais (no wind). He has a line he keeps for towing and I've been wondering if I should do the same in case I can return the favour to someone else. What length/size of line would be appropriate - we have an Oyster 406 so we won't be towing anything too big.

I was told "Always use your own line, This will considerably lower the chances in the unlikely event of the tower making a salvage claim against you".
Does this still stand? It was an awfully long time ago?

 

[fisherman]

Re: Joining long two lines - how to do it ?

extra master Graham Danton has a towline parcelled with canvas and copper sheet where it passes through the Panama fairlead.....

 

[bbg]

Re: Joining long two lines - how to do it ?

I tend to use double sheet bends instead of a standard sheet bend as the knot tends to be less tight, easier to undo after loading and more more secure or at least looks more secure.

That would have been my choice as well.

 

[[163233]]

Re: Joining long two lines - how to do it ?

Do you links to any load test data for that?

Double braid polyester seems you're better off with a bowline -

https://web.archive.org/web/20160318230212/http://www.bethandevans.com:80/load.htm

Average breaking strength as a % of rated strength(10 tests of each knot for 3 different lines)​

[TABLE="class: style62, width: 426, align: center"]
[TR]
[TD="class: style33, width: 54, align: center"]Bowline[/TD]
[TD="class: style33, width: 86, align: center"]Figure 8 Loop[/TD]
[TD="class: style33, width: 55, align: center"]Buntline[/TD]
[TD="class: style33, width: 118, align: center"]Double Sheet Bend[/TD]
[TD="class: style33, width: 113, align: center"]Double Fisherman[/TD]
[/TR]
[TR]
[TD="class: style33, align: center"]74%[/TD]
[TD="class: style33, align: center"]73%[/TD]
[TD="class: style33, align: center"]74%[/TD]
[TD="class: style33, align: center"]61%[/TD]
[TD="class: style33, align: center"]67%
[/TD]
[/TR]
[/TABLE]
2. The sheet bend slipped in all three lines. These are new lines, and more slippery than used ones, but it still suggests the sheet bend may not be very reliable (see tests of alternatives below in the "specialty knots" section).

Surprised at the double fishermans as I think that's what generally gets recommended for tying prussik loops?
I'd have gone for a carrick bend but I think it can jam after a heavy loading.

 

[zoidberg]

Re: Joining long two lines - how to do it ?

extra master Graham Danton has a towline parcelled with canvas and copper sheet where it passes through the Panama fairlead.....

"Worm and parcel with the lay......." Pass me the Stockholm Tar jar!

 

[Lodesman77]

Re: Joining long two lines - how to do it ?

Why has no-one mentioned the Figure 8 Bend (Flemish Bend)? Probably the least reduction in strength of any knot and easy to undo after loading.


edit: See here - https://www.animatedknots.com/fig8join/index.php

For extra security see at the bottom using double overhand stopper knot on each tail.

 

[prv]

Re: Joining long two lines - how to do it ?

I would and have used a carrick bend, with good long tails which I might stop back to the main line with twine or cable ties for neatness and a little extra (probably unnecessary) security.

As it happens, today at work I found myself dangling a very expensive piece of equipment on two joined ropes and used exactly this arrangement.

Pete

 

[LittleSister]

Re: Joining long two lines - how to do it ?

One suggestion is that both ends of the lines should be prepared with small soft eyes, and then be joined with a Swiftlink.

I don't know what a Swiftlink is*, but if you're going to form soft eyes in the ropes to be used, why not just make the loops a little longer and loop them together? (i.e. pass loop on Rope 1 up through loop on Rope 2, then pull the rest of Rope 2 through the loop on Rope 1).

(*Despite Googling - it seems a brand name used in lots of different fields.)

 

[zoidberg]

Re: Joining long two lines - how to do it ?

I don't know what a Swiftlink is*

In Oz they're called Quiklinks ( brand name ). Also know as a 'maillon rapide' when made by Wichard and S3i. Here's a selection....

https://www.s3i.co.uk/quick-links.php


All this presupposes the skills required to make eye splices that will hold under the loads envisaged. Not a 'given'.

 

[LittleSister]

Re: Joining long two lines - how to do it ?

In Oz they're called Quiklinks ( brand name ). Also know as a 'maillon rapide' when made by Wichard and S3i. Here's a selection....

https://www.s3i.co.uk/quick-links.php

Thanks. The things themselves are familiar, but I don't know they were called that (or that or that!).

 

[sarabande]

Re: Joining long two lines - how to do it ?

All kinds of useful ideas coming out of my question - thanks.

I didn't want to become too specific in terms of rope diameter and lengths, but just to find best practice and general principles.

As John Morris says, the snatch loads when towing are certain to exceed the force needed to tow in a flat sea, and I am surprised that I cannot find any figures for the force needed to drive/sail/pull a range of hulls at different speeds to act as a basis for calculations/estimate.

The suggestion to have a single really long rope has snags IMHO. I suspect that many towing situations are likely to be with short scopes perhaps 20 to 30 metres or less. A single rope of 100m is going to start to be unwieldy and heavy - the last thing one needs under pressure on a wet and heaving foredeck when trying to find the free ends of large mass of rope. 100m of 22mm multiplait weighs something like 32kg, and that is a bit of a beast to manage.

If using any of the suggestions for a soft or a hard loop, one would have to assume that it's prudent to arrange a few extra tucks in the splice , given the nature of the rope's purpose.

I am still of a mind to join two warps using a hard eye and shackle in one end of each rope. A couple of decent Crosby shackles with captive pins are easy and quick to join, and when secured with a beefy cable tie are very very unlikely to come undone. There's no uncertainty about a shackle whose pin is wound shut with a spike; it is not going to chafe or jam solid under load.

It's chastening to remember that Roger Taylor of MingMIng lost his jordan drogue when using a rope bridle - it just chafed through. A hard eye and shackle might have served him better on that occasion.

Lots of ideas for a bit of experimenting when next on board.

 

[fisherman]

Re: Joining long two lines - how to do it ?

Just to throw in another factor, wavelength can dictate towline length, to avoid the tow surfing down a wave face at the wrong moment.

 

[LittleSister]

Re: Joining long two lines - how to do it ?

As someone has mentioned, weight around the middle of the line will help reduce snatch. I think you'd need something much heavier than a tyre though (and how many carry tyres with them?) If joining your lines with hard eyes and shackles, why not a decent length of chain as the middle section of the line?

In any case, once you've got yourself a tow line to cope with these extreme loads, what is it going to be attached to on each boat?

 

[zoidberg]

Re: Joining long two lines - how to do it ?

If joining your lines with hard eyes and shackles, why not a decent length of chain as the middle section of the line?

That's an interesting thought. 'Str-e-e-tch' must be a factor.

In any case, once you've got yourself a tow line to cope with these extreme loads, what is it going to be attached to on each boat?

Probably the usual little Lego foredeck deck cleat that modern production boats are blessed with.... with obligatory brass screws, of course.

It may be worth restating the age-old practice of backing up the towing warp with additional lines taken to every strong point on the boat. Spreading the load - that's what 'dog stoppers/ring stoppers' were used for in the days of working sail.

 

[LittleSister]

Re: Joining long two lines - how to do it ?

That's an interesting thought. 'Str-e-e-tch' must be a factor.

The chain will have negligible stretch itself, but the catenary its weight creates will effectively provide stretch between the two attached points and reduce shock loading. Perhaps the deluxe version is a short length of chain either end to avoid chafe at the fairleads etc., then long stretchy nylon warps, in turn joined to a chunky chain central section.

Or 8-strand bungee jumping cord?

 

[Uricanejack]

Re: Joining long two lines - how to do it ?

I tend to use double sheet bends instead of a standard sheet bend as the knot tends to be less tight, easier to undo after loading and more more secure or at least looks more secure.

+1 quick easy, will work with any two ropes.