1:1 vs 2:1 halyard for Code Zero

[Adelie]

For a 2:1 system the direct compressive load on the mast drops by 50% for the tail down to the deck.
The compressive load from the sail side is the same.
The net compressive load is decreased by 25% or more. The more part is because the sail doesn’t pull down, it pulls down and forward so not all of the sail side load is down.
Then there is the indirect load. The sail is pulling to leeward, forward and down.
The forward load is resisted by the backstay and the compressive load in the mast due to the backstay is proportional to the forward load and some trig function for the angle between the mast and backstay.
The load to leeward is resisted by the windward shroud and the compressive load from the shroud is calculated in the same manner as for the backstay.

On ok approximation is to say that all the sail’s load is down and none is forward or to leeward. Then the compressive load in the mast is reduced by 25% using 2:1 halyard.

If you have 3:1 then it is reduced by 1/3.
4:1 reduced by 3/8
With and infinite ratio it reduced by 1/2.
Increasing purchase in the halyard is very quickly absurd. Better is to use 1:1 or 2:1 to get the sail up and have some latch mechanism at the top to lock the sail in the hoisted position and the halyard tail can be completely slack and you get 1/2 the compressive load in the mast without a million miles of halyard tail. I’ve seen 505s and Finns rigged like this.

[fxykty]

Originally Posted by Adelie

For a 2:1 system the direct compressive load on the mast drops by 50% for the tail down to the deck.
The compressive load from the sail side is the same.
The net compressive load is decreased by 25% or more. The more part is because the sail doesn’t pull down, it pulls down and forward so not all of the sail side load is down.
Then there is the indirect load. The sail is pulling to leeward, forward and down.
The forward load is resisted by the backstay and the compressive load in the mast due to the backstay is proportional to the forward load and some trig function for the angle between the mast and backstay.
The load to leeward is resisted by the windward shroud and the compressive load from the shroud is calculated in the same manner as for the backstay.

On ok approximation is to say that all the sail’s load is down and none is forward or to leeward. Then the compressive load in the mast is reduced by 25% using 2:1 halyard.

If you have 3:1 then it is reduced by 1/3.
4:1 reduced by 3/8
With and infinite ratio it reduced by 1/2.
Increasing purchase in the halyard is very quickly absurd. Better is to use 1:1 or 2:1 to get the sail up and have some latch mechanism at the top to lock the sail in the hoisted position and the halyard tail can be completely slack and you get 1/2 the compressive load in the mast without a million miles of halyard tail. I’ve seen 505s and Finns rigged like this.

With all the trouble that the Vendee boats had with their halyard locks, I’d be nervous of installing one.

[fxykty]

Originally Posted by SaltyMetals

I am not quite sure what you mean by a Code Zero. If it is a gennaker on a top-down furler then you will need a lot of tension on the torsion rope. I hv a 43 ft Jeanneau 43ds with a 1100 sq ft gennaker. Hauling the furled sail up to the top of the mast is the easy bit. The challenge comes when you need a v high tension for unfurling or furling. I found this v difficult with a manual winch but it is easy if i pass the halyard across to my electric winch on port. This means i am fine with my 1:1 and avoid all the extra "spaghetti" in the cockpit which would result from a 2:1.



If you are talking about a conventional sail rather than a downwind gennaker/assymetric then you should find a 1:1 perfectly adequate on your boat. If the Spinlocks are not holding yr halyard at yr chosen tension then there is a kit that Spinlock supplies to replace the inner bits that grab the line but try flushing the Spinlock out with fresh water first to see if that fixes it. Otherwise the inner bits of the Spinlock is an easy DIY replacement. This solution is probably cheaper than changing yr halyard to a larger diam.



Andrew

Sail name confusion I think. The Code 0 that the OP is referring to is a relatively flat sail for reaching that is flown from a bottom up furler and the luff is attached to the torsion cable along all its length. Gennaker is a more common cruising name for the same type of sail. The luff is captured, unlike the asymmetric spinnaker or multi purpose sail that you’re referring to with a top down furler and a loose luff.

The issue is not whether the halyard clutch can physically hold the line diameter - it is whether the tension on the halyard through the clutch is within the safe working load of the clutch. 2:1 halyard will half the tension at the clutch. The loads on the halyard with a Code 0/gennaker are much higher than what you use with a top down furler.

[SaltyMetals]

Tks. I should put a strain gauge on my gennaker halyard to figure out the high tension on the torsion rope because i was reluctant to reach such a high tension until a rigging guy told me it was safe. I thought it might have broken the Selden bowsprit or pulled it out of its socket or broken it in half. Neither happened. Much stronger than i thought.

If the OP is referring to a relatively flat sail ( as indeed it is so named by the racing guys as a Code Zero) then i see no problem with his 1:1 .

I don't like the 2:1 system because of all the spaghetti it leaves in the cockpit and also bec i don't need it with the benefit of my electric winch to get the high tension I need for the top down furler. Certainly a 1:1 is fine for me to manually raise the gennaker but i must admit to the cruising bible of doing it the easy way if you can. So I also use my electric winch also to haul up the gennaker. Lazy? Yes. Gives more time for a cool beer.
Andrew

[SVSweetestThing]

Originally Posted by fxykty

Sail name confusion I think. The Code 0 that the OP is referring to is a relatively flat sail for reaching that is flown from a bottom up furler and the luff is attached to the torsion cable along all its length. Gennaker is a more common cruising name for the same type of sail. The luff is captured, unlike the asymmetric spinnaker or multi purpose sail that you’re referring to with a top down furler and a loose luff.

The issue is not whether the halyard clutch can physically hold the line diameter - it is whether the tension on the halyard through the clutch is within the safe working load of the clutch. 2:1 halyard will half the tension at the clutch. The loads on the halyard with a Code 0/gennaker are much higher than what you use with a top down furler.

Yes, I am not concerned with the luft tightness rather the load. Thus trying to understand if rigging it differently, 2:1, is better and would relieve some of tghe luft tention.

Code Zero /Code 0, seen it both ways but yes, it's a reaching sail for lighter wind. came from racing but also used in cruising

https://www.uksailmakers.com/sails-o...sing-code-zero

[Joli]

A code zero is just a big jib, it requires luff tension to set properly. If you can generate the luff tension with your halyards your all set, if you can't then switch to a two to one halyard.

[Adelie]

Originally Posted by Joli

A code zero is just a big jib, it requires luff tension to set properly. If you can generate the luff tension with your halyards your all set, if you can't then switch to a two to one halyard.

A drifter is a very big, very light weight jib. It can be set flying or hanked to a forestay. It is a light air sail.

A CodeZero is a really flat asymetrical spinnaker usually set on a roller furling luff. It is always set flying. It can be a light air sail or it can be made of stronger material for use in mild to moderate winds.

Drifter will generally point higher. A CZ is usually bigger than a drifter.

[Alistair242]

We have a 2-1 halyard on our main which so far has been great and easy to raise. We also chose the option of a 2-1 halyard for our screecher. I assume as it was an option that either a 1-1 or 2-1 are fine. From the first time we raised the screecher we struggled with line twist. We raise it by hand about 95% and then put it on a winch to gain the right tension. I have removed the halyard, towed it behind the boat and re-installed. I have also been up the rig and manually taken out the twist. We do not twist the line when coiling. It’s big sail, about the same size as our main and can be used in up to around 16kts AWS.
On the weekend I succumbed and change the set up to 1-1. It was fine. Much faster to raise and no twist. We were able to get adequate tension but the real test will be close hauled in a decent breeze.
As someone suggested, you can set up a block at the tack and gain more tension there if need be. I’m not sure what we were doing wrong but the line twist made the 2-1 setup almost impossible. No such issue with the main?

[fxykty]

Originally Posted by Alistair242

We have a 2-1 halyard on our main which so far has been great and easy to raise. We also chose the option of a 2-1 halyard for our screecher. I assume as it was an option that either a 1-1 or 2-1 are fine. From the first time we raised the screecher we struggled with line twist. We raise it by hand about 95% and then put it on a winch to gain the right tension. I have removed the halyard, towed it behind the boat and re-installed. I have also been up the rig and manually taken out the twist. We do not twist the line when coiling. It’s big sail, about the same size as our main and can be used in up to around 16kts AWS.
On the weekend I succumbed and change the set up to 1-1. It was fine. Much faster to raise and no twist. We were able to get adequate tension but the real test will be close hauled in a decent breeze.
As someone suggested, you can set up a block at the tack and gain more tension there if need be. I’m not sure what we were doing wrong but the line twist made the 2-1 setup almost impossible. No such issue with the main?

The difference between a 2:1 and 1:1 halyard is the load on the clutch - twice as much with the 1:1. This may be too much when on a close reach or upwind. Sure, the tack purchase can help adding more tension, but keep in mind the load on the clutch rising when sailing.

Regarding the twisting 2:1 halyard, if it’s not the line then I expect it is likely that the fixed part of the halyard is too close to the lead block of the running part. They should be separated by at least 100mm. Also, ensure that no part of the halyard fixings can twist - not the lead block, nor the turning block that attaches the halyard to the top of the sail, nor the fixed end at the top.

Weird that you’ve got the issue you’ve got. We have had no issues at all with either our 2:1 main halyard, 2:1 screecher halyard, or 2:1 staysail halyard. I hope you can work things out.

[Alistair242]

It was very weird. Our main is fine too with a 2-1. I think the rope clutches we have are OK with the load and if not I can go back to a 2-1. I can also run the line to a winch or cleat after the clutch if it looks like the load will be high.
Initially the luff was a little too long and there was almost no space at all between the head block and the sheave. In fact we had to go to a smaller block. Since then the sail maker reduced the luff rope length by about 80-100mm and there is a little space. The fixed point at the bitter end up top cannot twist and there is a profurl swivel at the head below the block for furling.
I’ll see how I go but it seems to work much smoother since the switch.
It’s a fantastic sail and I envisage using it as much if not more than the self tacking jib. We need it to be easy to deploy and put away.

[nuku34]

Could we get clear with our sail terminology please?
Code 0 sails are NOT gennikers or asymmetrical spinnakers.

Code 0 sails are all basically light large jibs that are used in light winds, usually up to 12kts. They are used for beating and beam reaching (say down to 110˚). Code 0 sails always have a heavy line in the luff (because the luff, like any jib), needs to be relatively tight with not a lot of sag). They all are on furlers; they need to get furled at least partially when you tack. None are set flying without furlers. They are made of Dacron or some non-stretch material, NOT nylon.
By contrast, gennikers or asymmetric spinnakers are NOT meant for beating, but for beam reaching (up to say 70˚) and broad reaching down to around 140˚. They don’t get tacked, but are gybed, and are made of nylon. In general, gennikers are set flying like a symmetrical spinnaker, or used a snuffer. Some gennikers use top down furlers.
Because the luffs of Code 0 sails need a relatively high tension (as opposed to gennikers), the halyard gets quite loaded when the sail is at the top of its wind range. None of the racing boats I’ve sailed on (all 14m or less in length) use 2:1 halyards on their Code 0. Some have down hauls under the furling drums which lead back to winches. All these boats have fairly long prods (up to 2m long) with some sort of bobstay to take the huge upward load of a fully loaded Code 0.

[Alistair242]

Originally Posted by nuku34

Could we get clear with our sail terminology please?
Code 0 sails are NOT gennikers or asymmetrical spinnakers.

Code 0 sails are all basically light large jibs that are used in light winds, usually up to 12kts. They are used for beating and beam reaching (say down to 110˚). Code 0 sails always have a heavy line in the luff (because the luff, like any jib), needs to be relatively tight with not a lot of sag). They all are on furlers; they need to get furled at least partially when you tack. None are set flying without furlers. They are made of Dacron or some non-stretch material, NOT nylon.
By contrast, gennikers or asymmetric spinnakers are NOT meant for beating, but for beam reaching (up to say 70˚) and broad reaching down to around 140˚. They don’t get tacked, but are gybed, and are made of nylon. In general, gennikers are set flying like a symmetrical spinnaker, or used a snuffer. Some gennikers use top down furlers.
Because the luffs of Code 0 sails need a relatively high tension (as opposed to gennikers), the halyard gets quite loaded when the sail is at the top of its wind range. None of the racing boats I’ve sailed on (all 14m or less in length) use 2:1 halyards on their Code 0. Some have down hauls under the furling drums which lead back to winches. All these boats have fairly long prods (up to 2m long) with some sort of bobstay to take the huge upward load of a fully loaded Code 0.

We are clear. In this part of the world we often refer to a large reaching sail as a screecher(particularly on multihulls) and they are pretty much the same as your Code 0. We can use ours anywhere from about 40 degrees apparent to almost DDW if shaped properly. However the sail is predominantly for reaching and being closed hauled in light air and we need considerable luff tension to achieve this effectively. We fly it off a 2m bowsprit with a continuous furler and as said we had the option of either 1-1 or 2-1 halyard and I can now see the advantages of both. It has a high tension torq rope through the luff which it furls around.
We also carry an asymmetrical spi.
.

[GRIT]

Nuku34.

I have to disagree with your statement in general.

Our Code 0 is made of heavy nylon. Secondly, Spinnakers are rated by size and use, from 1 to 6, and I would argue that the actual ratings are 0-6.

I understand racing rules tend to treat code 0 as a spinnaker.

I know several folks who have code 0 made of nylon, and Rolly tasker offers code 0 made of this material as well (mine is a Mack Sail).

Here's how Rolly Tasker's site describes a Code 0:

Code Zero
Cruising Code Zeros are designed with straight luff incorporating an anti-torsion rope and a small positive roach for stable trim and easy handling. They can be built out of heavy spinnaker cloth, which is most competitive, or a laminate for more demanding cruising sailors. Race Code Zeros are built out of Dimension Polyant CZ Laminate. The mid girth of Racing Code Zeros is designed to be 75% of foot to avoid rating penalties which does mean a small downturn in wind range and handling but this is accepted by racers because of the advantages in rating.

North Sails has this to say:

“Code Sail” is a general term for a specialized class of fast, flat and furling-capable downwind sails that are defined by mid-girth measurements between 50%-75% of foot length. These sails fit between upwind headsails and downwind spinnakers. Code Sails are especially effective on high-performance monohulls and multihulls. The Code Zero model meets the minimum 75% smg requirement to be classified as a Spinnaker for certain rating rules.

Cheers.
Paul.