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TOPIC: Downwind head sails for the Pacific

Downwind head sails for the Pacific 4 months 2 days ago #3469

  • Dick
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Hi WB,
I keep hearing and reading about the twizzle/twistle rig and were I to be rounding the world in the conventional manner (or contemplating any significant trade wind sailing), I would assuredly check it out. Sounds like the rig checks a lot of boxes. Thanks for your report.
Dick Stevenson, s/v Alchemy

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Downwind head sails for the Pacific 2 months 3 weeks ago #3537

  • Ginger
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Hi David,
I thought you might be interested:
www.nytimes.com/2017/02/02/world/asia/china-junk-builders-hong-kong.html?ref=world&_r=0
Such a shame when an art form dies away,
Dick Stevenson, s/v Alchemy

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Downwind head sails for the Pacific 2 months 3 weeks ago #3541

  • simoncurrin
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Posted on behalf of David (s/v Serendipity)

A twin headsail rig was the initial downwind rig on our circumnavigation. We sailed about 10,000 miles with it but its disadvantages eventually proved its downfall. Let me explain.

If you are going to sail the classic milk run route across the Atlantic, the twin headsail set up works well because once you turn west the wind is generally pretty much dead aft. It can be a bit of a palaver to set up even on the dockside – and even with a dedicated halyard for the second headsail run from the foredeck through a block attached at the head of the genoa. You rig it with one headsail poled out to windward with the spi pole braced for and aft, the other sails sheet led through a block on the end of the boom (braced with a preventer). (I have no experience of the Twistle Rig).

This is a very versatile rig, easy to adjust when a squall approaches, and can easily be rolled away out of harm’s way. In my view it is pretty bombproof. It is true that, if the sails are both in the foil’s luff groove(s) there is a small risk that the foil can split in a squall but you can easily guard against that by keeping a roll in the furler.
This rig works well if the true wind is above say 15kts (i.e. trade wind conditions) and the rig can be carried safely day and night. If the wind does go light, the rig can easily be rolled away and the pole is already rigged and braced for a cruising chute or similar.
I used to be a big fan of this set up but over time its shortcomings began to take their toll:
• It can be very rolly, there being no dampening from the main.
• You can only use it with the apparent wind circa +/-140 degrees – less if there is any appreciable rolling. (If you have twin poles when maybe +/-130 is possible). (Note that this is a real drawback once you are through Panama because in our experience the wind was pretty much on the quarter 120/130 degrees apparent for most of the rest of the circumnavigation.)
However, probably its biggest drawback on a long passage is that, when the wind goes ahead you find the windward sail backs and needs to be taken over to leeward. If you set lazy sheets that is easy enough. However, you can’t sail like that indefinitely; there is small but appreciable movement between the two sails which will chafe through the stitching and shorten the life of both sails. So if you are going to sail like that for any length of time (my guide was 12 hours) then one or other head sail has to come down. That is not too hard to do, but when the wind goes aft again and you want to re- erect the twin headsails you are in for much fun and games in a rolling and pitching sea. It is very difficult to do on my boat, even in a calm sea – and pretty nigh impossible short-handed. So once it was down – it stayed down till the end of the passage – perhaps several days later leaving you without a downwind rig for the rest of the passage, other than light winds.
We found a much more versatile set up was to brace the mainsail to leeward with the preventer, lead the genoa sheet through the spi-pole braced to windward – a classic poled out genoa. However, if you are lucky enough have a cutter rig, then then fly the staysail on the leeward side at the same time, but strapped in quite tight. The staysail funnels the wind onto the genoa then through the gap between them and provides substantial resistance against rolling, making the journey much more comfortable.
We used this rig for the remaining 35,000 miles – often in preference to a cruising chute, simply because it requires little attention. You can carry this rig +/- 120 degrees because you can trim the head sail independently. The main advantage is that if the wind goes ahead you can take the headsail to the other side easily to reach for a while then when it goes aft again it is simple to re-erect at sea.
You can’t sail as deep with this rig as you can with the twin headsails, so you will need to gybe down wind to maintain boat speed. However, because there is less roll and less slack in the sails, it is a quicker rig than twin headsails by some margin. It is hard to provide hard evidence to support that statement, other than I believe it and that our average days’ run had increased by more than 15% by the end of our circumnavigation compared with the first 10,000 miles.
With the twin headsails, we were quick to reach for the cruising chute to keep us going when the wind dropped. With this poled out headsail with staysail, the speed penalty was not too hard to bear; after a while, unless the wind got really light, we wouldn’t bother with the cruising chute. Slept much better

Chafe

Flying a downwind rig for any length of time does introduce chafe problems particularly at the spi-pole end – we had the rig collapse on to the guardrail more than once eventually necessitating a replacement spi-pole. By the end of the circumnavigation, we were rigging the end of the pole with a small rope grommet through the fixed eye. To that we attached a block and ran the sheet through that to avoid friction. The snap shackles on the end of the guys and uphaul will eventually to wear a groove in the aluminium pole end so our fore and aft guys/downhauls were knotted onto the grommet using a round turn then a bowline; the uphaul knotted similarly to the top of the pole. This eliminated friction and thus chafe – at the spi pole end at least!

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Downwind head sails for the Pacific 2 months 3 weeks ago #3546

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Hi David,
A really nice contribution and especially nice as it is a field report with clearly a lot of miles under your keel. You depict the advantages well.
You might be interested in my “Taming the Downwind Whisker Pole” and my “Offshore Asym” articles on the OCC site as I think you will find our thinking overlaps considerably.
A couple of thoughts:
In strapping in the staysail is good advice, but those with radar on the front of their mast should be aware they will likely need to roller reef a couple of turns or their leach may rub on the radome.
In strapping the main down, a bulletproof preventer set up is absolutely essential for safety of crew: for the best sail shape and for protection of the sail from chafe, a very robust boom vang/kicker is also essential. Both are likely to get well tested.
A spin pole is not a good pole for most cruising boats, especially if a crew of two/husband/wife: much too heavy and too short. Most of us never fly a symmetrical spinnaker. Much better to get a pole sized to the largest headsail: you will expose more sail area and it is kinder to the sail. Better yet, get a carbon fibre pole and feel much safer on the foredeck and (my opinion) stay away from adjustable poles. (see above referenced article)
With regards to chafe, I suspect some of that was generated by the spin pole being too short and allowing movement. A properly sized whisker pole allows the whole set up to be more firmly set up and mitigates some of the chafe.
Thanks again for your report,
My best, Dick Stevenson, s/v Alchemy

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Downwind head sails for the Pacific 2 months 3 weeks ago #3549

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Reply from David Caukill and posted on his behalf

Serendipity’s genoa is 140%. The pole is just less than 21 feet long; it is made from carbon fibre and protrudes about 3 feet beyond the forestay. With some planning, two fit people can rig it without too much trouble; clearly three people is easier. There is no way I want to muck about, short-handed on a bouncy foredeck, with a longer pole - - whether on a mast slide or not. And we do fly the asymmetric from the pole from time to time particularly with the wind dead aft in light airs.
Chafe arises from a changing load on the rig. This can arise as flogging when the rig is too slack and the sail collapses and refills, and is characterised by a noise, a ‘crack’, as the sail refills, or from cycling or pumping - the sail remains filled, but changes of pressure from rolling, coming up out of a trough or a simple gust, increase the pressure on the sails and the tension on the rig. Both of these are a source of chafe.
We brace the pole and boom as tight as possible, all of the lines are led to dedicated winches and these can be cranked as tight as reason permits (as can the preventer against an hydraulic vang). I omitted to mention that when we set the rig, we spend quite some time with fine adjustments to minimise flogging, else the sail flogs noisily and in the long run expensively. Our objective is to set the sail so it remains filled as the boat rolls. In a stiff breeze that is easy but in lighter airs we need to take a roll or so in the genoa to flatten it and adjust the pole height and position in order remove the belly and to try to get the ‘shoulder’ and the foot as tight as possible.
The usual culprits as far as chafe is concerned are not the sheets (these are easily protected). It is the pole up haul and the asymmetric halyard which are prone to failure on the mast sheeve and when it fails then either the pole crashes onto the guard rail or you sail over your kite.
On each of the lines on the pole, there is probably 65 -75 feet from winch to shackle and there is inevitably some give along their length. It takes the slightest stretch to cause chafe when there is something to chafe against. Even our spectra tack line, for the asymmetric, pumps back and forth more than an inch through the block with each roll/pitch of the boat. (To mitigate this, we relieve it with a rolling hitch, shortening it considerably).
Even when flogging is minimised, it is hard to stop the sails pumping and the load cycling as the boat rises from a roll or trough. The resulting stress loading is either dissipated as noise or absorbed by give in the sails and rigging – as stretch of the running rigging, cycling of standing rigging, shear in the fabric of the sails and stitching …… or a combination of them. Once we eliminate one risk of wear, we transfer the risk somewhere else. Then, rather than these forces being absorbed by things that are relatively inexpensive to replace, one is now looking at replacing the standing rigging before the mast falls down. Sailing is full of compromises; If I’ve got to replace something, I’d rather it was running rigging.
So we stay alert for it, regularly adjusting the running rigging positions very slightly to change the wear point, ideally every 12 hours (it is logged) … but I have little hope of eliminating it.
I could go on …….
Looking back through this thread I can see that I have little chance of having the last word ….. in it but I do hope I have the self-restraint to make this my final word.

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Downwind head sails for the Pacific 2 months 3 weeks ago #3550

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reply posted on behalf of Dick Stevenson

Hi David,

No, please do not make this your last word: you have a lot of good things to say. You have worked hard and anyone wishing to go downwind will benefit from your reports.

And I would very much hope to shift from a head-set of “last word” to one where we have exhausted what I hope to be experienced as suggestions that may prove helpful, probably not so much for you with your experience, but for others who might read this stream. Just as anyone reading your reports will benefit a great deal.

I suspect that I have a somewhat smaller boat as my 110% jib topsail is taut to the end of my carbon fibre 19 foot pole and I agree that getting things firmed up pays dividends at mitigating chafe.

Your analysis of the chafe occurring on downwind passages is right on. Chafe happens, but every now and again there is a way to prevent it: for years, I used a topping lift line (pole up haul) that came out of the mast and suffered chafe and occasional ruined halyard just as you reported. I then switched to use the spinnaker halyard as my topping lift. This halyard also emerges from the mast, but, on my boat, then goes through a block that articulates in all directions to give a fair lead and no chafe.

My best, Dick Stevenson, s/v Alchemy

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Downwind head sails for the Pacific 2 weeks 6 days ago #3779

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I simply sail to a reach . Boat goes faster and is stable .
If I need a spinnaker I fly it minus pole . Helm then needs little adjustment . Read Eric Hiscock ^ Beyond the Western Horizon ^ if you dont believe me . I reef early and shake them out asap .
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Downwind head sails for the Pacific 2 weeks 6 days ago #3780

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Hi Chris,
Thanks for your comments. Could you elaborate a bit?
When you say, “sail to a reach”, do you mean what is commonly called, gybing downwind? Destination dead-down-wind (DDW) and one gets there on broad reaches gybing when necessary.
Is the spinnaker referred to a symmetrical or asym? Without a pole are you sailing the spin like a big genny, tack at bow and sheeted well aft?
Thanks, Dick Stevenson, s/v Alchemy

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Dick Stevenson, s/v Alchemy
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