Headsail halyard loading

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Dave100456

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I’m planning on a twin headsail setup utilising both foil luff grooves. What sort of load can be expected on the second ‘temporary’ halyard which I’m keen to keep as short and small a dia as possible? Luff length is 17 metres and sail area 40 m sq.

Internet searches suggest the same dia for main and genoa halyards but surely with all the friction and support offered by the foil, the tensional load on the luff will be significantly less than on a main halyard.

I’m not bothered about handling the line as it will be a ‘hoist once’ and used only for running so trimming, camber and C of E do not come into it.

I was thinking that halyard loading would be a lot less than 1,000 kg so I could go down to 5 or 6 mm Braid on Braid.

What’s the forums view?
Thanks
 
An interesting question.
The numerical answer will depend on a great many things.
But a thin halyard which stretches in every gust might have a short life.
 
Our genoa halyard is never winched particularly tight - to avoid distorting the sail shape. Perhaps brief one handed shove on the winch to finish off. Massively less force than needed for our mainsail, which gets ground up bar tight, full muscle and four turns on the winch to go to windward in any breeze.
This may depend on the individual sail shape, but a downwind twin jib is unlikely to need much luff tension.
I would think thin but dyneema would be the way to go - prob 6m as anything less may slip in stoppers, or worse slip off the side of the masthead sheave.
 
In my view the friction in the furling foil will only increase the halyard loading necessary to get the luff tension you need. Otherwise, a genoa is just like a mainsail but a bit bigger, needing more luff tension upwind than downwind and extra luff tension in a blow to pull the draught back forward to where you want it. Presumably you will only use the twizzle rig downwind, which will reduce the tension required compared to a general purpose genoa. All things considered a halyard as strong as the main halyard seems sensible for both genoas. Our second genoa halyard was the same size as the main and genoa 1 until we replaced the main and genoa 1 halyards with a low stretch (not dyneema, one of the cheaper imitations), now genoa 2 and the spi halyards are the fatter (but no stronger) ones. I agree that less than 6mm, regardless of material would not be sensible.

Peter
 
PeterWright said:
In my view the friction in the furling foil will only increase the halyard loading necessary to get the luff tension you need. Otherwise, a genoa is just like a mainsail but a bit bigger, needing more luff tension upwind than downwind and extra luff tension in a blow to pull the draught back forward to where you want it. Presumably you will only use the twizzle rig downwind, which will reduce the tension required compared to a general purpose genoa. All things considered a halyard as strong as the main halyard seems sensible for both genoas. Our second genoa halyard was the same size as the main and genoa 1 until we replaced the main and genoa 1 halyards with a low stretch (not dyneema, one of the cheaper imitations), now genoa 2 and the spi halyards are the fatter (but no stronger) ones. I agree that less than 6mm, regardless of material would not be sensible.

Peter
Click to expand...

I’m not using a twizzle rig but do intend to fly both headsails. It would be easy to attach the heads of the two headsails to the same halyard and hoist together. However this would mean taking both down first in order to drop one. I want to hoist sail number two independently and plan to attach a block to the top furling swivel with mouse line/ lightweight halyard.

I agree that upwind the halyard tension increases, however, on a run both the luff tapes exit the foil aft and then fold part way around the foil meaning friction almost holds the sail up. This is evident by the large forces if you try to tension the luff when the sail drawing.
Once the sail is drawing on a run if the halyard were released I do not think the sail would go far.

Perhaps the question I should be asking is does a stretchy halyard make much difference when the foresail is poled out downwind?
 
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Something with 100Kg breaking strain would be fine for your stated use (the biggest load it would see is the weight of the person pulling it), and stretchy would't matter either.

Big but though - it would be a shame not to take advantage of using it as a back up to the other genoa halyard or future use with a spinnaker. I'd spend the extra.
 
anoccasionalyachtsman said:
Something with 100Kg breaking strain would be fine for your stated use (the biggest load it would see is the weight of the person pulling it), and stretchy would't matter either.

Big but though - it would be a shame not to take advantage of using it as a back up to the other genoa halyard or future use with a spinnaker. I'd spend the extra.
Click to expand...

Thanks, I tend to agree that the maximum force will be when it’s being hoisted.
I have a couple of spinnaker halyards already and as this halyard has to furl it is limited to use for the headsail.
 
Yes the forces on a jib when running down wind will be fairly light. However I would think it desirable to have 2 halyards the same so that you always have a spare jib halyard. So fit another full sized dyneema halyard. ol'will
 
Interesting post, thank you.
I have long been thinking of hoisting/setting my old (light-weight) genoa using the second slot/groove and your question/answers seem to support my thinking. I have a masthead spinnaker halyard which I have decided will hardly ever get used as I don't like spinnakers (single-hander!)
I would use the second genoa with my main genoa in a sort of trade-wind rig
going down-wind, but presumed I would have to down the second sail before coming onto the wind.

If I have missed something which would suggest the second sail could be left "up" when coming more onto the wind, please advise me of the what, how and what if!

Many thanks

​
 
Robert Wilson said:
Interesting post, thank you.
I have long been thinking of hoisting/setting my old (light-weight) genoa using the second slot/groove and your question/answers seem to support my thinking. I have a masthead spinnaker halyard which I have decided will hardly ever get used as I don't like spinnakers (single-hander!)
I would use the second genoa with my main genoa in a sort of trade-wind rig
going down-wind, but presumed I would have to down the second sail before coming onto the wind.

If I have missed something which would suggest the second sail could be left "up" when coming more onto the wind, please advise me of the what, how and what if!

Many thanks

​
Click to expand...

Only issue in using the spare spinnaker halyard is that you won’t be able to shorten the sail(s) as the spinnaker halyard would be wound around the top of the foil/ forestay.
However, with the second halyard having its top attachment point on the top swivel you can furl both sails together if conditions get lively.
 
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Dave100456 said:
Only issue in using the spare spinnaker halyard is that you won’t be able to shorten the sail(s) as the spinnaker halyard would be wound around the top of the foil/ forestay.
However, with the second halyard having its top attachment point on the top swivel you can furl both sails together if conditions get lively.
Click to expand...

Would that mean that both sails have to be hoisted together, at the same time? If so, then both sails would furl-up together when "reefing" as you indicate ​
and also when furling away, e.g. after sailing?

I was thinking more of hoisting the second sail up the groove as and when conditions/desire prompted.

Or have I made an impossible assumption?
 
Robert Wilson said:
Would that mean that both sails have to be hoisted together, at the same time? If so, then both sails would furl-up together when "reefing" as you indicate ​
and also when furling away, e.g. after sailing?

I was thinking more of hoisting the second sail up the groove as and when conditions/desire prompted.

Or have I made an impossible assumption?
Click to expand...

Hoisting with spinnaker halyard means you can hoist as and when and drop each sail independently. What you will not be able to do is roll the sails up unless you connect a block to the top swivel.
Video explanation here
https://m.youtube.com/watch?v=G8LmSX-vEys
 
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Dave100456 said:
Hoisting with spinnaker halyard means you can hoist as and when and drop each sail independently. What you will not be able to do is roll the sails up unless you connect a block to the top swivel.
Video explanation here
https://m.youtube.com/watch?v=G8LmSX-vEys
Click to expand...

Gotcha.
Thank you for that. A well presented and helpful video.
I think I need to rummage in my Bosun's stores for more blocks 'n' bits :encouragement:
 
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