Pulling the wind forward off the wind

[Sparx]

I am thinking again about a "Code Zero" sail for my Maine Cat 38. I am interested in your input on design aspects and features that make the sail very usable. Usability includes ease of launching and furling, strong enough to carry on in a breeze, able to live furled on the bow sprit for extended periods, and relaxing to use when cruising.

This new sail is intended to fill the gap between jib and spinnaker, to the extent of being the preferred downwind sail for all but the deepest of angles. This sail must be easy to use and stable even when pulling strongly.

There is already a large assyemtrical spinnaker, which certainly pulls the boat well at deep angles. The spinnaker is launched from a sock. In practice the spinnaker often is not used just because it take a fair bit to get it launched and requires full attention while it is flying, it is rarely relaxing.

So give me your thoughts on the features of a good reaching and deep angle sail that is relaxing to use.

I am ambivalent about top down versus bottom up furling. Educate me please.

I am thinking not so big, say about 500 square feet, nominally 50 square meters. About twice the size of the jib and half the size of the spinnaker.

And here it gets interesting...

For background this Maine Cat 38 commonly pulls the wind foward 30 to 40 degrees flying the main and jib up to about 110 AWA where the jib loses power. I am thinking this feature of pulling the wind forward should be considered in design of the new sail. To what extent this holds up in practice at increasing angles is something I would like the benefit of your experience. Those with fast cats please chime in here.

With a boat that pulls the wind forward I am thinking I should go with a somewhat flatter sail designed for say 90 to 120 AWA thinking this would translate to a true course as much as 150 off the true wind. What does it take to continue to pull the wind forward when sailing increasingly deep angles? Up in the lulls and down in the puffs is surely part of it, but what are the features of a sail that is stable and pulling well in shifting AWA?

I would like to keep the sail on its furler mounted on the bow sprit when we are actively cruising. I understand many sails with light cloth are highly susceptible to UV damage, even with a sunbrella protective strip. I also understand top down furlers may not hold the sail tightly furled in a blow. Set me straight here if I am misled.

[catsketcher]

A cruising Code 0 is a great sail. I use normal bottom up furling with an anti torque line. My sail is an old reacher cut to fit my boat. I can't see why you would top down furl a cruising Code 0. Cruising Code 0s are not more than 75% girth, like a racing Code 0, so they are much easier to furl bottom up.

It pulls the apparent forward so that I can broad reach in light winds with the apparent on the beam - we can do almost windspeed in flat conditions. Champagne sailing in 8-10 knots doing 8 when others are motor sailing.

As for shape - talk to a sailmaker. They will probably recommend you reduce mid girth to about 60-70% to get the sail to set and furl better. As for steering, that is the great thing about a 0, they allow you to set a magnetic course and they don't collapse like a kite, so you don't have to steer up and down, although you could if the autopilot has wind direction.

I drop mine after sailing. I can't bear the thought of all that weight up high and out the front of the boat when going to windward making me hobbyhorse . I put a fair bit of effort into reducing weight in the ends and keeping a Code 0 up high and way out front is not going to happen on my boat. Also the things can un furl on their own and that is really bad news. But some people leave them up, but I don't mind the couple of minutes to put it away safe and sound. I go faster when it is up and because I stow it, I go faster when it is down.

Norths did a good video on zeros

https://www.youtube.com/watch?v=yuchPjjHKKI&t=2080s

[fxykty]

These flat reaching sails for multihulls are called screechers or gennakers. They are flatter than typical code 0s. Bottom up furling with a big anti torque cable - the loads climb quickly with more wind. You’ll need a 2:1 non-stretch halyard for it.

Our gennaker is an old, heavy and bulky Dacron triradial with some perished material on the edges for UV protection when furled. It is cut flat enough that it can set all the way down to 45* AWA, though that is about 80* TWA, so definitely too big and fast for upwind work. It is huge (120sqm) - the clew nearly reaches the aft corner when sheeted in tight against the cap shroud. The sail has an upper limit of 15 knots AWS - this is to protect the rig.

This sail is flat, so is best suited to close through beam reaching. We use it down to 120* AWA, or even deeper if we move the tack to the windward bow. It’s a good moderate wind reaching sail - we’ve had it up in 20-23 knots TWS at 120-130* AWA and with the boat speed only 10 knots AWS. If we’re lazy we’ll use DDW without a mainsail; otherwise we use the autopilot on apparent wind mode to sail an S course to keep the apparent wind up. We hand steer when we want to have some fun surfing.

We leave it up and furled if we expect more reaching or very light conditions, but it’s a lot of windage and the UV isn’t good for it. If we’re expecting upwind conditions it definitely comes down right away.

Our replacement will be a laminate (like CZ90 or TEC10) sail, which should halve the weight and size of the current sail. It will have UV protection material but we still won’t leave it up all the time.

[Sparx]

[QUOTE=fxykty;3671241
This sail is flat, so is best suited to close through beam reaching. We use it down to 120* AWA, or even deeper if we move the tack to the windward bow. It’s a good moderate wind reaching sail - we’ve had it up in 20-23 knots TWS at 120-130* AWA and with the boat speed only 10 knots AWS.
[/QUOTE]

What TWA does this sail deliver? What you describe is what I am interested in.

[Sparx]

Tell me about your process for getting the sail off the bow sprit and stored. And then out of storage, fastened on the sprit and ready to launch. This works for me if it is fast and only a few steps.

One of the problems with the spinnaker is getting it on deck is a two person job. Then running the sheets, then hoisting the sock, then launching takes a bit of time. If the down wind course is only an hour I usually just skip the spinnaker.

[fxykty]

Originally Posted by Sparx

What TWA does this sail deliver? What you describe is what I am interested in.

Roughly 70-150 TWA

[fxykty]

Originally Posted by Sparx

Tell me about your process for getting the sail off the bow sprit and stored. And then out of storage, fastened on the sprit and ready to launch. This works for me if it is fast and only a few steps.

One of the problems with the spinnaker is getting it on deck is a two person job. Then running the sheets, then hoisting the sock, then launching takes a bit of time. If the down wind course is only an hour I usually just skip the spinnaker.

Our furled gennaker is a long and bulky sausage up to 20cm in diameter (remember that we have a 16.4m long boat and the luff is 17.5m) and weighs about 20kg. We store it in a sail locker where it is folded up. It has two long and heavy sheets (14mm double braid) and a furler drum and 25m of 8mm furling line with three double blocks.

We have a 2:1 halyard with a soft loop that goes around the shackle on the top swivel - an easy no-tools way to make the connection.

We have a low friction fitting on the bottom of our furler - the tackline starts at the end of the pole, goes over the friction fitting, then goes through a low friction ring also attached to the end of the pole. The tackline then leads back to a cleat on the front beam. The tackline is 2:1, which lowers the loads on it and the cleat (our sail has about 3,000kg luff cable load at the top of its range).

If it is in the sail locker it is easier for two people to handle it and it can be raised by halyard out of the locker. When the sail is 3/4 up we stop hoisting while we connect the furler to the tack and to the tack line, which can be pulled back from the front beam for easy access, then pulled out to the end of the bow pole. Then we finish hoisting the sail. Last jobs are to lead the sheets to their aft quarter turning blocks and to lead the furling line along the starboard stanchions. This all takes about 10 minutes before we are ready to unfurl.

If only one person then it is pulled out of the locker and arranged on the trampoline. The furler is attached to the tack and to the tack line. The sheets and the furling line are lead. Then a second person is called to hoist the sail - one person on the halyard and the other guiding the sail so it doesn’t blow back into the mast. This all takes about 15 minutes before we are ready to unfurl.

That is why we will leave it up if we expect to use it again the next day. In that case it is just like a furling jib. I see lots of boats that leave them up all the time.

If we’re not sure that we’ll want to use it again within a few days and are coastal sailing in generally benign conditions then we’ll drop the furled sail onto the trampoline and disconnect the halyard and furler from the sail. Everything else gets left in place (sheets, furling line, furler connected to the tack line). We have a large sausage bag attached to our trampoline that holds the furled sail. When we want to use the sail we connect the tack to the furler and the halyard to the head and hoist it, a matter of minutes.

Your sail and associated loads will be much less than its so everything will be lighter and easier to handle.

[Sparx]

Fxykty,

Thanks for your detailed reply. This is very helpful.

Your TWA performance is exactly what I am hoping for.

I see lots of boats with their screechers hoisted and furled while out cruising. So much so that I came to think these sails more or less lived every day hoisted. It seems logical to stow the sail for serious windward work, but leave it hoisted for a normal mixed wind cruising day. I could see myself doing as you describe.

Your hoisting procedure is nearly the same as my spinnaker hoist, the difference being you sail is on a furler while mine is in a sock. It takes me about 15 minutes, same as you describe. My take away is that there is no crafty sailor trick I am missing.

The spinnaker is huge and cumbersome. I am thinking the proposed tightly furled screecher will be less heavy and a much smaller total package.

Again thanks for the detailed response.

[Tupaia]

Our screecher is roughly the same size as our main 65 and 63 sqm respectively.

It has no UV and is made from DP "code zero" material. It has a high cut clew to just clear the coach roof and enables it to be sheeted inboard of the shrouds to the jib sheet tracks. It has a torque rope on a Pro-Furl drum furler. We have a whisker net below our prodder to enable easy access to unhook it. It only has one sheet. It comes down when not in use and is stored in an apron locker or lashed on the tramp. Under moderate wind sailing conditions it disturbs the airflow ahead of the jib and requires huge halyard tension even when furled under these conditions to stop it from gyrating.

It excels in light winds TWS up to 10knts abaft the beam or there abouts. We have achieved constant 10kt boat speed in 8kts TWS on the beam, the AWS was about 13kt and an AWA of just under 40 degrees. (the upper limit for the sail is 15).

The high clew allows it to be sheeted very tight down to 35 degrees apparent but the halyard tension is hard to achieve unless the winds are very light. If the clew is too low you will not benefit from being able to pull the apparent wind forward.

We also use it at night wing on wing with the jib deep downwind as it is simple and quick to furl it there is a squall.

[CatLove]

It's great that people share their experiences with code zeros reachers and gennakers. One thing to keep in mind is that this sail has to be designed with characteristics that match the boat and the owner's sailing style.
Not all boats pull the wind forward the same angle or up to the same windspeed . This effect is very visible on fast lightweight boats with oversized rigs , maybe rotating masts but it diminishes greatly for slower heavier less performance oriented boats.
A very fast boat never runs dead downwind , it sails a broad reach playing angles for best VMG . Depending what wind speed multiplier the boat is capable of, the apparent wind is pulled forward more or less. If the boat can pull the AWA more forward, the sail needs to be flatter . The opposite is true for a condomaran.

So bottom line the sail should be designed for the specifics of the boat. Look at the polars to get a rough idea.

[Sparx]

Originally Posted by Tupaia

Our screecher is roughly the same size as our main 65 and 63 sqm respectively.

It has no UV and is made from DP "code zero" material. It has a high cut clew to just clear the coach roof and enables it to be sheeted inboard of the shrouds to the jib sheet tracks. It has a torque rope on a Pro-Furl drum furler. We have a whisker net below our prodder to enable easy access to unhook it. It only has one sheet. It comes down when not in use and is stored in an apron locker or lashed on the tramp. Under moderate wind sailing conditions it disturbs the airflow ahead of the jib and requires huge halyard tension even when furled under these conditions to stop it from gyrating.

It excels in light winds TWS up to 10knts abaft the beam or there abouts. We have achieved constant 10kt boat speed in 8kts TWS on the beam, the AWS was about 13kt and an AWA of just under 40 degrees. (the upper limit for the sail is 15).

The high clew allows it to be sheeted very tight down to 35 degrees apparent but the halyard tension is hard to achieve unless the winds are very light. If the clew is too low you will not benefit from being able to pull the apparent wind forward.

We also use it at night wing on wing with the jib deep downwind as it is simple and quick to furl it there is a squall.

Thanks for these details.

I have two sail designs on the table at the moment.

A AWA 70 to 140 "Code Zero" of 860 sqft. A much flatter screecher more AWA 40 - 105 sail of 560 sqft. This screecher sail would have a tension cable in the luff. Both sails have similar luff, foot, and leach dimensions, the difference being the amount of curve in the sail shape. Which ever I choose I plan to put the sail on a furler.

Under main and jib on any reach other than a tight reach the wind is pulled forward 30 to 40* typically moving at 65% of TWS. Under spinnaker the boat sails as high as 100 AWA, while pulling the wind forward 30 to 40*, resulting in a course made good of 140 to 165 of TWD. In 12 knots TWS flying the spinnaker the boat is moving 8+ knots over the ground. 8 kn is a very acceptable downwind cruising speed for our 38 foot boat.

From this discussion I am leaning towards the screecher. From this discussion it looks reasonable to get as deep as 135* TWA with the screecher pulling strongly, and possibly have it also useful even deeper in wing and wing mode. I like the suggestion of flying the screecher wing and wing when cruising, especially at night.

The collective group responses indicate success with relatively heavy dacron construction, but also a thought that when you replace the sail going with a lighter weight material. I have proposals using 1.5 oz nylon, but am looking into other choices too.

I can easily configure an adjustable tack line as FXKTY describes. I have been looking hard at the Harken Reflex furler, but would prefer a single line furler if I can find one with good features.

[Tupaia]

Originally Posted by Sparx

Thanks for these details.

I have two sail designs on the table at the moment.

A AWA 70 to 140 "Code Zero" of 860 sqft. A much flatter screecher more AWA 40 - 105 sail of 560 sqft. This screecher sail would have a tension cable in the luff. Both sails have similar luff, foot, and leach dimensions, the difference being the amount of curve in the sail shape. Which ever I choose I plan to put the sail on a furler.

We retired our asymmetric, and gave it away, when we got our screecher. The hassle of using it for such a small speed benefit over using the screecher as an MPS with a barber hauler on all points when cruising was just not worth it.

Originally Posted by Sparx

Under main and jib on any reach other than a tight reach the wind is pulled forward 30 to 40* typically moving at 65% of TWS. Under spinnaker the boat sails as high as 100 AWA, while pulling the wind forward 30 to 40*, resulting in a course made good of 140 to 165 of TWD. In 12 knots TWS flying the spinnaker the boat is moving 8+ knots over the ground. 8 kn is a very acceptable downwind cruising speed for our 38 foot boat.

From this discussion I am leaning towards the screecher. From this discussion it looks reasonable to get as deep as 135* TWA with the screecher pulling strongly, and possibly have it also useful even deeper in wing and wing mode. I like the suggestion of flying the screecher wing and wing when cruising, especially at night.

It really depends on your use. Ocean sailing or passage making with only 2 on board the screecher wins hands down. Coastal cruising over relatively short distances when both are awake the asymmetric has the edge in certain conditions.

Originally Posted by Sparx

The collective group responses indicate success with relatively heavy dacron construction, but also a thought that when you replace the sail going with a lighter weight material. I have proposals using 1.5 oz nylon, but am looking into other choices too.

For the screecher I would go for a technical cloth, Dacron is too heavy and you will sacrifice the really light wind performance where it excels and Nylon is too stretchy for wind ahead of the beam. Buy the screecher first and try it out, it will transform the boat.

Originally Posted by Sparx

I can easily configure an adjustable tack line as FXKTY describes. I have been looking hard at the Harken Reflex furler, but would prefer a single line furler if I can find one with good features.

I have a drum furler primarily because the furling line is on the centreline of the boat and uses the mast platform to transfer it to the cockpit. If you have access then a continuous line furler would probably be better. Be sure of your safe loadings before buying this is especially important if the sail is to be used at low AWA's. My 65sqm screecher has a 4tonne drum and a 2.5tonne upper swivel. Also check that the water stay attachments are strong enough and the top mast is adequate. The loads are huge.

[Sparx]

Originally Posted by Tupaia

I have a drum furler primarily because the furling line is on the centreline of the boat and uses the mast platform to transfer it to the cockpit. If you have access then a continuous line furler would probably be better. Be sure of your safe loadings before buying this is especially important if the sail is to be used at low AWA's. My 65sqm screecher has a 4tonne drum and a 2.5tonne upper swivel. Also check that the water stay attachments are strong enough and the top mast is adequate. The loads are huge.

The primary reason I prefer a single line drum furler is the reason you stated. All sail controls presently run to the enclosed helm in the deck salon. I have not yet imagined how to bring a continuous line loop into that space, which would require passing through a foam and glass panel to land at a cleat. I can easily see cutting and sleeving a single hole in the panel for one line, but getting a loop through and running fair requires a bigger hole.

The Facnor FXT is a commonly used single line furler for code zeros and screechers. I am concerned the small diameter drum will make furling in a breeze difficult. Looking for better suggestions, or experience that says the Facnor is up to the task.

BTW, this boat has got a well stayed prodder and a double halyard set up to carry a
screecher, so just need to add a sail and a furler.

[Tupaia]

Originally Posted by Sparx

The Facnor FXT is a commonly used single line furler for code zeros and screechers. I am concerned the small diameter drum will make furling in a breeze difficult. Looking for better suggestions, or experience that says the Facnor is up to the task.

Have a look at Profurl also. The small drums are not an issue, firstly the sail won't be up in a strong breeze and secondly you can let the sail stream out in front of the boat. This is easier if the clew is high cut as any tension on the seat during furling is more central on the luff.

[Happ]

Originally Posted by Sparx

I am thinking again about a "Code Zero" sail for my Maine Cat 38. I am interested in your input on design aspects and features that make the sail very usable. Usability includes ease of launching and furling, strong enough to carry on in a breeze, able to live furled on the bow sprit for extended periods, and relaxing to use when cruising.

This new sail is intended to fill the gap between jib and spinnaker, to the extent of being the preferred downwind sail for all but the deepest of angles. This sail must be easy to use and stable even when pulling strongly.

There is already a large assyemtrical spinnaker, which certainly pulls the boat well at deep angles. The spinnaker is launched from a sock. In practice the spinnaker often is not used just because it take a fair bit to get it launched and requires full attention while it is flying, it is rarely relaxing.

So give me your thoughts on the features of a good reaching and deep angle sail that is relaxing to use.

I am ambivalent about top down versus bottom up furling. Educate me please.

I am thinking not so big, say about 500 square feet, nominally 50 square meters. About twice the size of the jib and half the size of the spinnaker.

And here it gets interesting...

For background this Maine Cat 38 commonly pulls the wind foward 30 to 40 degrees flying the main and jib up to about 110 AWA where the jib loses power. I am thinking this feature of pulling the wind forward should be considered in design of the new sail. To what extent this holds up in practice at increasing angles is something I would like the benefit of your experience. Those with fast cats please chime in here.

With a boat that pulls the wind forward I am thinking I should go with a somewhat flatter sail designed for say 90 to 120 AWA thinking this would translate to a true course as much as 150 off the true wind. What does it take to continue to pull the wind forward when sailing increasingly deep angles? Up in the lulls and down in the puffs is surely part of it, but what are the features of a sail that is stable and pulling well in shifting AWA?

I would like to keep the sail on its furler mounted on the bow sprit when we are actively cruising. I understand many sails with light cloth are highly susceptible to UV damage, even with a sunbrella protective strip. I also understand top down furlers may not hold the sail tightly furled in a blow. Set me straight here if I am misled.

Two suggestions. Check out Harken’s Reflex Furler. It can accommodate any sail. A very clever set up. The change you make is each sail you want to furl will use the corresponding tack and head fitting from Harken. There are 3 different sets of fittings available. So you sew on the fittings for your asymmetric and you can top down furl it. Want to use the Code Zero? Lower the asymmetric to the deck on fast pin allows the sail to be disconnected from the Furler. Same pin connects the Code Zero.

AS for the sail look at North’s website. They have some very interesting different shapes for Code sails. Their new Helix with a structured luff is the. Most interesting concept I’ve seen to this day.

For those that think North is for racers only, they are the largest cruising sail maker in the world.

I am not affiliated with NOrth. I have been a customer though.