rope shackles - what stops them shaking loose?

[Ric]

Thinking of using a rope shackle for my genoa sheets. But something puzzles me looking at pics - what stops a slack shackle from shaking loose?

Also, should I use just one shackle and thread both sheets through it? Or separate shackle for each sheet?

Finally, what size shackle? My boat is 31ft and sheets are 12mm.

 

[Norman_E]

You only use one rope shackle, and both sheets are attached to it. The best way is to have eye splices on the sheets, and pass the rope shackle through both of them and the cringle. Because rope shackles are impossible to undo under tension, and one or other sheet is always in tension whilst sailing, they do not shake loose. I have used the system for about 5 years without problem.

As for size my 45 foot boat has a 4000Kg rated shackle and 16mm sheets. A 2000Kg rated shackle will be fine for a 31 foot boat. Lower rating would probably be OK but the diameter of the dyneema shackle would then be rather small compared to the sheet.

 

[Leighb]

They cannot shake loose, the turks head (or whatever) is held very tight by the eye which tightens under load, they are not easy to undo when not under load.

Concerning size, the first year I had them I used the smallest which is plenty strong enough, but the eye splice on one genoa sheet started to slip. I took it into the rigging shop who had made up the sheets for me, the rigger looked at it, and said that basically the eye splice was deformed by having too small a rope. Since then I have used the next size up with no problem.

Another forumite has used one shackle with no trouble, I plan to do that next season as it would be neater.

 

[JayBee]

...Because rope shackles are impossible to undo under tension, and one or other sheet is always in tension whilst sailing, they do not shake loose.

Not always. Quite often during a tack, when the sail is perhaps flogging for a few moments, it is possible that both sheets will be slack. Not in a perfect world, of course. That's when I would be watching for sod's law to kick in. I am going to give one of these a try, anyway.

 

[vyv_cox]

As said earlier, the Turks Head knot is large and is very effectively held by the eye in the outer braid. It takes some effort to release the shackle when required.

We have used this one for quite a few years now, the photo was taken in 2009 when it may have been a year old. We still have the same one, now covered many miles and many tacks. It has never come undone.

 

[DJE]

I've been thinking of trying one of those to connect the mainsheet block to the traveller so that I can easily move it out of the cockpit when in harbour. Would a soft shackle be suitable in that location?

 

[prv]

Can someone remind me what the benefit is over tying each sheet into the cringle with a bowline? Not trying to be a smartarse, just decide if I want to go the same way

Pete

 

[Deleted member 36384]

Can someone remind me what the benefit is over tying each sheet into the cringle with a bowline? Not trying to be a smartarse, just decide if I want to go the same way

Pete

Simplicity, you just have a plain end sheet, no need for anything else. Before the ubiquitous roller furling systems changing head sail only required the sheets to be knotted without recourse to other items of kit. Off the top of my head thats about it. It would also make end for ending a sheet easier to extend its life in the days when such things mattered.

 

[Buck Turgidson]

Can someone remind me what the benefit is over tying each sheet into the cringle with a bowline? Not trying to be a smartarse, just decide if I want to go the same way

Pete

Off the top of my head:

Larger cringle required for 2 sheets rather than one shackle. This may limit the sheet diameter or weaken the clew area.
2 sheets to chafe the cringle rather than the shackle.
Failure of the cringle may render the sail inoperative.
If the shackle fails it's easy/cheap to replace.
You can use eye splices on the sheets if a shackle is used.

 

[prv]

Simplicity, you just have a plain end sheet, no need for anything else. Before the ubiquitous roller furling systems changing head sail only required the sheets to be knotted without recourse to other items of kit. Off the top of my head thats about it. It would also make end for ending a sheet easier to extend its life in the days when such things mattered.

I'm confused. I asked why these soft shackles are better, and you seem to be telling me why I should use knots instead.

Pete

 

[Stork_III]

I've been thinking of trying one of those to connect the mainsheet block to the traveller so that I can easily move it out of the cockpit when in harbour. Would a soft shackle be suitable in that location?

I use captive snapshackle on each end of mainsheet, for moving to rail in harbour and also to reverse mainsheet for MOB lifting. Fortunately not use the latter in anger.

 

[prv]

Larger cringle required for 2 sheets rather than one shackle. This may limit the sheet diameter or weaken the clew area.

I suppose - but does anyone make sails that won't fit two lines through the clew? Most cringles are plenty big enough.

2 sheets to chafe the cringle rather than the shackle.

The cringle is made of stainless steel. I suppose you could chafe the cloth around it, but since only one sheet is loaded at a time I'm not convinced it's any worse.

Failure of the cringle may render the sail inoperative.

Same for both techniques, surely?

If the shackle fails it's easy/cheap to replace.

If you don't have a shackle, it can't fail

You can use eye splices on the sheets if a shackle is used.

Why is that a benefit?

Pete

 

[prv]

reverse mainsheet for MOB lifting.

So would you get the sail down and stowed before attempting to lift someone? How do you plan to stop the boom swinging around (whether sail up or down) in a rolling boat, once you de-rig the mainsheet?

Pete

 

[Buck Turgidson]

I suppose - but does anyone make sails that won't fit two lines through the clew? Most cringles are plenty big enough.



The cringle is made of stainless steel. I suppose you could chafe the cloth around it, but since only one sheet is loaded at a time I'm not convinced it's any worse.



Same for both techniques, surely?



If you don't have a shackle, it can't fail



Why is that a benefit?

Pete

Aesthetics

But I prefer sheets bowlined directly to the cringle for the simplicity.

 

[Highndry]

Are soft shackles OK for use on a foresail that's hanked on rather than on a furler? I suppose the question is, will the soft shackle be up to being attached/removed on a daily basis?

My sheets are currently attached to the fore with a heavy steel shackle. I like the idea of the weight saving but am slightly concerned at the turk's head going in and out of the shackle repeatedly!

 

[vyv_cox]

Can someone remind me what the benefit is over tying each sheet into the cringle with a bowline? Not trying to be a smartarse, just decide if I want to go the same way

Pete

The big advantage for me is that sheets bowlined to the cringle catch on the babystay when we tack. This was always a problem despite various rollers around the stay. With the soft shackle there is a considerable improvement.

 

[Deleted member 36384]

Can someone remind me what the benefit is over tying each sheet into the cringle with a bowline? ......

Simplicity ......

I'm confused. I asked why these soft shackles are better, and you seem to be telling me why I should use knots instead.

Pete

I did miss read your question.

Well to be clear I am not advocating that rope shackles should not be used. I prefer the simplicity of plain end sheets tied to the clew. One benefit is that the rope shackle solution doesn't foul shrouds or inner forestays like a bowline would for example, although other knots can be used to prevent this fouling. Having experienced fouling by the bowline I don't rate the solution of a rope shackle as worth the bother of eye splices and rope shackles. The utility of a cringle that takes knotted sheets and the use of plain end sheets is of more use to me. The rope shackle is an unnecessary addition as far as I am concerned in this application.

 

[prv]

The big advantage for me is that sheets bowlined to the cringle catch on the babystay when we tack. This was always a problem despite various rollers around the stay. With the soft shackle there is a considerable improvement.

OK, thanks. First genuine answer to my question

I don't have a babystay on the new boat, so will wait and see if I have snagging issues before making any changes.

Pete

 

[EdWingfield]

I've tried purchasing dyneema to make them myself but have failed.

Q. Who sells them plz?

 

[vyv_cox]

I've tried purchasing dyneema to make them myself but have failed.

Q. Who sells them plz?

Mine came from Compass 24