Windshackles - still daft.

[Frangipani]

I’ve just choked on my Horlicks.

There was a good deal of discussion a couple of months ago about John Perryman’s article on “windshackles”, in which he had suggested that sheets should be fitted with weak shackles which would fail as the vessel was getting over-pressed (see “Failsafe Rigging Failures in CB”, 20-25 Jan). The broad concensus was that it wasn’t just “daft” (John’s own word), it was potentially very dangerous. I for one sent a letter, reiterating what I had said on this forum, to the effect that nothing should replace the exercise of good seamanship, which includes early reefing and a keeping a weather eye open, not building in failure in inappropriate places.

I didn’t expect it to be published, but nor did I expect a letter backing him up, which I’ve just read in the May edition. I doubt Andrew Smith would have been quite so supportive if the jib sheet had parted while he was trying to claw off a lee shore, nor if he had suffered a Chinese gybe, caused by his kicking strap parting when he was running downwind. The key sentence in his letter is “we were hit by a thunderstorm which had been building all day, but for which we had done little to prepare.” Just backs up everything that was said in this forum.

I know that John Perryman is the Consultant Editor of CB, but it still seems strange that the chorus of criticism which greeted his idea is ignored in favour of someone supporting his view. Is Andrew Smith’s letter really representative of the correspondence on the issue? If not, then it seems irresponsible to continue in recommending a potentially dangerous design feature.

Good oh - that's two rants I've managed to get out of this subject. I'm off for a lie-down....

 

[JREdginton]

I have got to go get a copy of this, a weak link in a sheet, bl**dy h**l! What next, a failsafe keel that will detach from the hull to prevent getting stuck in the putty or sails with velcro'd slots in case you forget to reef /forums/images/graemlins/laugh.gif

 

[Porthandbuoy]

Ahem. My letter covered an actual experience where "weak points" in the rigging may have prevented more serious damage from occurring. In no way does it vindicate my lack of preparedness for the fury of a Mediterranean thunderstorm. That was my error and mine alone. As is often pointed out experience is something you don't have until just after you need it!
I believe Johns article was aimed more at big ships, square riggers and the like, rather than workaday yachts.

 

[ccscott49]

Weak points in the rigging??? Are you Joking??
What a bloody stupid idea! Weak points are just that, weak, what heppens when they let go at the wrong time? How do you adjust the weakness?
Quite simply stupid!

 

[JREdginton]

Assuming you DO install weak links in to rigging/sheets/what have you. Just how do you deal with a sail flogging or a spar running wild once it is no longer restrained? Is it not equally likely that the flogging sail or whipping spar will damage itself or other components. Have you tried to control a headsail wihtout sheets attatched, the thought of applying this to a square rigger with the additional mass of spars to contend with scars me to death.

Most of us get caught on some occasion or another, I know I have been, and try as I might I fear I will be again, but to suggest that we need to create 'failsafe' system such as this to remove our need to learn from those experiences and possibly create another series of dangers is foolishness.

Is it not just as easy to reef early or even let fly the sheets if you have failed to do this? At least you have some control on the sails as and when you have sorted yourself and the boat out.

 

[Porthandbuoy]

Let me play the devil's Advocate here. Your rigging, everybody's rigging, has a weak point. You may not know where it is, but it is there.
Sheets are invariably selected on account of their handling comfort, not breaking strain. Every shroud, shackle, swage, T-ball, chainplate will have a breaking strain. Do you know where the weak point is in your rigging? "Mine doesn't have a weak point" is not a valid answer.

If you read John Perryman's article you might have noticed he made reference to the loss of a sail training ship which was laid flat, filled, and sank. His comment was that in the "old days" something would have given way; a sheet or a shroud which would have spilled the wind either by letting a sail flog or a mast go by the board, allowing the ship to right itself and give the crew a second chance at recovering the situation. Modern synthetic materials are so so strong this cannot happen. Hardly perfect I acknowledge, but a valid argument.

To my own personal experience. I was sailing a CATAMARAN which cannot heel over and spill the wind like a monohull. If it does you are in even bigger trouble!
In a catamaran you don't bear up into a gust, you bear away to reduce the apparent windspeed and reduce the heeling moment. Yes I know I was sailing a Catalac, not some ocean greyhound, but the principle remains the same.

In the early days of catamaran development it was even proposed they be fitted with sheet jammers that release under excessive load; a similar idea in many ways to John's. The purpose being to prevent a capsize.

So, back to the opinion that designing in a weak point is a stupid idea. I take it you are happy for the clew of your jib to tear, or a swage terminal to pull out, or a chainplate to rip out of the deck, and just trust to luck on which it will be?

John_E. In no way am I implying that knowing what will fail eliminates the need for learning from experience.

 

[ccscott49]

I thought there was a system for cats, that when the boat heeled too much (whatever that means) the sheets were let go, not released completely, but let go and could be re-taken in. Much better idea than something breaking under load, I repeat my earlier post, how do you decide what to calibrate such a breaking failsafe to?

By the way, Yes I am prepared to have something I dont know about break, thats what checks and seamanship are about, being able to cope.

As for the tallship being knocked flat, well, if you dont want to get into trouble, stay in the bar or harbour. We are talking about a dangerous enviroment, no I agree we dont want to make it aymore dangerous than it is, but failsafe?? No thanks.

 

[KenMcCulloch]

[ QUOTE ]

If you read John Perryman's article you might have noticed he made reference to the loss of a sail training ship which was laid flat, filled, and sank.

[/ QUOTE ]
I didn't read the article but I assume he is referring to the loss of 'Marques' in the 1980s. She went down because hatchways were poorly designed and permitted downflooding at an otherwise perfectly survivable angle of heel. I don't think there's any evidence that rig failure would have helped her.

 

[JREdginton]

[ QUOTE ]
I take it you are happy for the clew of your jib to tear, or a swage terminal to pull out, or a chainplate to rip out of the deck, and just trust to luck on which it will be?


[/ QUOTE ]

No, not really. The fact is that the majority of vessels are designed for the rig NOT to fail! Maintenance is a key issue here. But if the worst happened I would deal with it if and when it happens to the best of my abilities. I still would not want to invite such a failure with the inclusion of 'weak links'. 'Weak links' too would also be up for wear and tear, so require additional maintenance to ensure they failed at the right moment. Assuming we (sailors) maintained our rigs what need is there to maintain 'weak links' too?

As yet, I have been very lucky as I have not had anything of this ilk happen to me yet! Twice in extreme conditions, hundreds of miles offshore,I have been rolled, (once under bare poles, once under trysail) on neither occasion did I loose a rig or part of the rig and contiuned the ocean crossing OK. Assuming we had 'weak links' installed we would have been adrift in the middle of the ocean with no rig (assuming water is more destructive than air). Not my idea of a good time. If the rigs had of been lost during either of these rolls then the situation would have been the same, but thanks to good prep, good fortune, and NO 'weak links' this did not happen.

As for looking at larger vessels, prehaps this will lend some weight to the 'no weak links' argument also ... http://en.wikipedia.org/wiki/Sailing_ship_accidents ... The first paragraph petains rig damage!

I stand by my call, a 'weak link' in the rig (shrouds, sheets, stays, sails) of a sailing vessel is just foolishness.

 

[grumpydog]

Frangipani - I'm afraid I didn't see your letter. The one we published (in favour of windshackles) was the only one we received. As the topic seems to have caused some controversy, I will publish an 'anti' letter in July, and let John P know of these comments so he can reply to the letter. Would you mind PMing me with your letter if you still have it to hand?

Thanks. Steffan Meyric Hughes, news ed, CB

 

[Frangipani]

My sincere apologies – please forgive my late-night flippancy: it was not my intention to cause offence. As you say, experience is what you have just after you needed it, and my primary concern was that someone less experienced may have read John’s article and think it was a good idea.

I wasn’t having a go at John either. We all have “bright ideas”, which quite don’t stand up to reality. To recap: his idea was that sheet blocks on square riggers should be fitted using shackles which would fail at a certain load, leading to the largest sails being automatically released if the ship becomes over-pressed. As the wind increased, so succeeding sails would be let go, until only the smallest sails were left drawing.

Quite apart from the safety considerations of having blocks flailing around whenever it gets windy, my own experience of tall ships suggests that his idea would not work for the following reasons:

1. Except for the courses (lowest sails), almost all square riggers (except replicas such as Rose, Grand Turk et al) actually lead the sheets through sheaves in the yardarms, rather than blocks.

2. The largest sails are lowest down, and cause less heeling moment than the smaller sails higher up. For instance, the forecourse on the Cutty Sark was a little over 2000 sq ft, with a centre of effort about 35 ft above the waterline. The fore royal was about 800 sq ft, centre of effort 130ft above the waterline (I’m ready to stand corrected on the exact figures, but they’re “close enough for Govt work”). Simple maths tells us that the smaller sail actually contributes 50% more to the heeling moment than the larger sail, because of its height.

3. It takes no account of point of sail. The loading on the topsail sheets of a square rigger hit beam on by a F8 gust while under full canvas will be the same as for the same vessel scudding downwind under foretopsail only in a F10. In the first situation she is in peril, in the second she is perfectly safe – until the “windshackles” decide to call it a day, of course, in which case she’ll be pooped by the next big wave.

4. His idea takes no account of luff tension. Take a small square rigger such as Royalist. The topgallant is about 200 sq ft. Given that a 30knot wind (F7) exerts a pressure of 4 pounds per sq ft, the total pressure would be 800lb. If this is spread equally, 50% of the load is taken by the topgallant yard, 25% by each of the sheets. Therefore the load on the sheet will be about 200lb. But square riggers need luff tension to get to windward, just as much as any other sailing vessel, and half a dozen burly blokes sweating up on a 2 x 3 halliard purchase can quite easily get a luff tension well in excess of this. (70lb pull per man x 6 men x 6 (power ratio) - 50% (10% per sheave) – weight of yard and sail (300lb) = 960lb overall tension = 480lb per sheet.

5. He assumes that a large sailing ship = large rigging loads. In fact, square rig is an attractive sail training tool, because you can run quite large vessels with a sail plan split into small areas, so rigging loads are light enough for youngsters to handle. The ropes which you find on a 100-150ft square rigger are just the same 12-14mm size as you’d find on a 30-40ft yacht. Finding shackles which can reliably fail at such light loading would be problematic to say the least.

All that, however, is beside the point. My actual query was about the editorial decision to back up JP’s article, given there had been such scepticism about it. At the very least there should have been a note for less experienced readers: Don’t try this at home!

 

[ccscott49]

I agree, the editorial decision was not only wrong, but ill thought and even could be considered dangerous. IMHO.

 

[Porthandbuoy]

Colin
It seems a little strange to me that CB's decision to publish an account of an actual experience, rather than opinion (however well informed) can be considered wrong. If my experience serves to support your views on the matter, while serving as a cautionary tale to those who have never considered it, all well and good.

David
No offence taken. Everyone seems to be convinced I am of the opinion that every yacht should be fitted with "wind shackles". Nothing could be further from the truth. I was merely passing on a bit of experience that led me to believe there may be a case for something along the line of "wind shackles" in certain circumstances. I do believe however that we should all know where the weak links are in our rigging, whether designed in or not.

 

[grumpydog]

The Letters page is a forum for CB readers to have their voices heard. Andrew Smith's letter recounts a real, true experience. It's not my policy as Letters editor, to edit or 'ban' the truth. Opinions vary on the subject of wind-shackles as the above demonstrates. Andrew Smith thought they were not such a daft idea and I will not censor him for that. I also wouldn't censor anyone who disagrees with him. So, if anyone would like to PM me a letter condemming wind-shackles I would be more than happy to publish that on the letters pages too.
Steffan Meyric Hughes, news editor, CB