Spinnaker or Code 0

[BigNut]

The fittings we inherited are for a continuous-line furler. It is my understanding one can add a “luff tape” to the sail (as well as a lightweight sacrificial strip) to allow roller furling for a gennaker.
Is this correct?

[fxykty]

Originally Posted by wingssail

So Tupaia, is that big flat sail a Code 0 or a Screecher, or what do you call it? and how is it different from the two I just named?



True I don't really know squat about multihulls, just what I learn talking to multihuller people, there are a lot of them around, and most are not as dismissive of know nothing mono guys as you, but we must all prove our superiority somehow, I guess. But I'd like to learn, so tell me more about the sail you have, and also why you don't think there is any value in an assym sail for multihulls even when the destination is truly downwind, do you always reach hard enough to bring the apparent wind abeam?



In this photo, what is the guy doing wrong? Could a table cloth or a sheet really serve?

Attachment 222762



When I look at the polars for an Outremer 45 I see the best TWA for downwind VMG is about 145deg. Would you say a code zero is effective for that wind angle? (or would it be an Assym kite?)



Attachment 222763



So what exactly is wrong with the recommendations for having both on a multihull? What is it we are missing?

For a performance boat like the O45 polar diagram you attached then the optimal VMG at around 150 TWA would need a flat asymmetric that can handle 115 AWA in 15 knots TWS. A code zero or screecher (essentially the same thing, though screechers are cut for close upwind and code zeros for slightly wider angles) would work, though in lighter air a fuller sail might be needed, hence a top down furling asymmetric like the pink one in the photo.

But the OP has a slower cruising cat and won’t benefit as much from hotter angles - at some point it’s just easier to take down the main, point dead downwind on your course, and fly a large symmetric or asymmetric spinnaker on its own. In that case the full asymmetric spinnaker is more useful than a much flatter code zero/screecher that just doesn’t have the sail area for wider angles.

Our O55L (first gen) has a self tacking jib, so we have two additions to our white sail plan for cruising: a screecher for light wind close hauled (40+ AWA from the bow prod and useful to about 140-150 AWA tacked to the windward bow in stronger winds), and a symmetric spinnaker for 130-180 AWA when we can’t be bothered to heat it up. When we have some extra money (ha-ha) we will replace the symmetric with a top down but flattish asymmetric spinnaker that will work 120-160 (lighter winds only on the closer angles) and OK to DDW.

[arsenelupiga]

Originally Posted by fxykty

The asymmetric on its top down furler will be easier to put away in the case of a squall - just let the sheet fly and furl it from the cockpit, while the spinnaker will need to be socked or otherwise lowered from the trampolines.

in gust trying to take it down - huge say 150m2 flapping with another 50 m of sheet rope flying around.... what can go wrong ?!

[barnakiel]

A torsion rope seems more popular than a tape. I remember tapes on early sails but later various kinds of torq ropes prove better in use.


Technically all sails have a luff tape, but we are talking a special one.


Also to furl it on a tape or on a torq rope its luff must be short, but many gennakers have longer luffs. For these look up top down furlers.


b.

[wingssail]

Originally Posted by arsenelupiga

in gust trying to take it down - huge say 150m2 flapping with another 50 m of sheet rope flying around.... what can go wrong ?!

arsenlupiga, (sorry for another comment from a monohull sailor)

I agree with you.

It is my opinion that the top down furler, while faster in normal conditions and very useful on a race boat in all conditions due to the reduced time it takes for sail evolutions, can be a handful. You are right, lots can go wrong when the wind is up.

I don't have any experience with one myself but I've watched other boats try to deal with them in gusty conditions and they often have a struggle even with full crews. We really advocate simple approaches. Don't add labor saving devices which also add complexity.

We don't use these spinnaker tools, but we have a rule about spinnakers: When cruising with the two of us on board don't set it in over 20 kts, and we take it down when the wind reaches 25 knots.

Like I said, we do not use a furler, and we do not use a sock. One person goes to the foredeck and pulls in a sheet or guy (we do this with either Assym kites or symmetrical, we have both). The other person steers and handles the halyard. When the sail is collapsed behind the main, (which it will do in any breeze) the halyard is dropped as quickly as the person forward can gather it and stuff it down the open hatch.

This is quick, very quick, and generally easy. We've had foul-ups, such as when some of the sail gets blown off the deck and into the water, but it has never been hard to recover the wet sail. It is important for the person steering to keep the sail calm and blanketed.

Here is Judy doing it in moderate conditions. We've let the pole go foreward to help put the sail behind the main. The second picture shows some guests who had never been on a boat before taking down the big A2 kite, also in moderate conditions. Looks like they are having fun, right?

[fxykty]

A cat is not a monohull and is completely different for handling sails in a cruising context. Wings, you’ve got plenty of racing experience that most cruisers do not, so what’s easy for you is not for the rest.

Using a sock on a spinnaker makes it a one person job - set the AP for whatever course you’re on, and if conditions warrant and you’re not already close to downwind then alter course closer to downwind, ease the sheet such that the spinnaker is close to collapsing (no need to let it go fully), go forward to the trampolines and pull down the sock, go to your halyard and lower the sock (if possible, bring the halyard tail forward so you can guide the sock into the trampolines. If it’s just a squall and you plan to use the spinnaker again then don’t lower the sock. With a sock there’s no need to hide the spinnaker behind the main, which may not even be up.

With a top down furler the furling is a little trickier than with a bottom up furler. When I wrote ‘let the sheet fly’ I only meant to de-power the sail in the gust. If you want to furl it then the sheet has to be brought back in to partially fill the sail. That can be done once the boat is under control and settled. A bottom up furler is easier - you can furl the sail successfully with the sheet completely loose (though the flogging is hard on the sail material and will result in a loose roll that can blow open even with the furling line cleated).

To furl a top down sail there must be quite a lot of sheet pressure to ensure the upper part of the sail is stretched out and pulling on its luff - otherwise it won’t start furling up there. Furling can be a two person job with one easing the sheet as the other winches or hand pulls the furling line, but one person can do this by alternating the jobs every few metres.

Top down furling sails have a furling technique that needs to be learned, but it’s not rocket science. Single handed racers use a combination of bottom up and top down furlers depending on the sail they’re using. For cruisers anything sail handling-wise that works for single handed racing is a candidate for use on short handed cruising boats

[Sparx]

So where is the break point in sail design that makes top down furling favorable over bottom up?

I can see a spinnaker wide at the mid cord needing top down. However say a screecher with 70% mid cord would be nice to furl bottom up?

[fxykty]

Originally Posted by barnakiel

A torsion rope seems more popular than a tape. I remember tapes on early sails but later various kinds of torq ropes prove better in use.


Technically all sails have a luff tape, but we are talking a special one.


Also to furl it on a tape or on a torq rope its luff must be short, but many gennakers have longer luffs. For these look up top down furlers.


b.

Length of the luff has nothing to do with top down vs bottom up - it’s the girth of the sail above the midpoint and whether the luff is free or not. If the sail is too full up high a bottom up furler will leave a big unfurled balloon in the middle, hence top down furlers were developed. Refer to https://info.upffront.com/blog/top-d...ce?hs_amp=true.

The racing world has developed cable-less luffs for jibs and code sails - instead of a separate torque cable (typically Dyneema or other proprietary fibres), the sails themselves have carbon (and other) fibres laid lengthwise along the luff to effectively create a stiff luff to transmit the turning moment and around which the sail furls. Our new staysail is of this construction and the front 100mm of the luff is very stiff.

[sailjumanji]

How big is the boat? We have an asymmetric spin on a Harken Reflex 2 top down furler. Not that big - about 1,120 ft2 (104 m2) - as its on a 38 ft cat. Found it fairly easy to furl, and once wrapped up, it drops down nicely onto the tramp. We have a large rectangular bag for storing on the front tramp.

Also, I didnt bother running the furling line back to the cockpit. Just to a stantion near the front window. Just walk up to front deck, have my wife toss of the sheet, and then I furl. After in the bag, I release the furling lines and toss them into the bag as well. Drum goes in there too. It's easy to clip all of this stuff back on before hoisting.

[BYA2014]

Originally Posted by ewishki

Going to replace my sails and want to add either a spinnaker or code 0. Which should I pick? I love the look of the big spinnaker flying but will the code 0 give me more options and performance?

Does depend on your goals and suggest consulting with a sailmaker.

If looking for a single, light air/offwind sail, a good case could be made for an Asymetrical spinnaker--though different sailmakers have different versions and names.
In lighter air, you can point quite high with this. In normal conditions its a reasonable compromise for greatly enhanced offwind performance. Cost is reasonable. (Don't need a lot of other gear). Deployment and take down relatively simple and appropriate for short handed sailors (Typically with the use of a sock). You can have a colorful sail if you like.

Article for Lightair/downwind sail choices (Mostly for catamarans, but pretty much appropriate for most cruising boats.)

[grube]

I had a chute-based gennaker converted to a Code 0 on a roller furling system that one could set up and put away quickly. It was a charm and helped to win a race or two. Pretty good for an older Hunter 380!

[SteveSadler]

I opted for a code 0 but after using it I wish I had a screecher instead. In light winds the 0 isn't really big enough but does point higher. The screecher is way bigger and more usefull downwind, but still points high.

[fxykty]

Originally Posted by SteveSadler

I opted for a code 0 but after using it I wish I had a screecher instead. In light winds the 0 isn't really big enough but does point higher. The screecher is way bigger and more usefull downwind, but still points high.

Hmmm, for our boat the screecher (light air upwind) is quite a bit smaller (80 square metres) than the code zero (light/medium air close reaching), which design shows 110 square metres. Both sails can be used for reaching and broad reaching to about 150 AWA, but are both too flat for true efficiency.

The sail type graphic posted just before tells the story, but is missing a screecher: that would be furthest to the left from 45 degrees TWA to 90.

So for two non-white sail furling sails you could have an asymmetric spinnaker for reaching to near dead downwind (and all the way downwind if the main is dropped) and a screecher for upwind and close reaching.

The screecher is only needed if you have a relatively small head sail, say a self-tacking jib (like we do). If you have an overlapping genoa then a code zero may make more sense, providing a bit more power for close reaching and reaching, but not useful (needed) for close hauled.

[Chotu]

Starting to wonder. Why DO we have these little self tacking jibs at all when a screecher and asymmetrical spinnaker can be set up on furlers?

I had a cutter rig on my old gulfstar and used the similar staysail a grand total of never.

I realize the shape isn’t perfect when you hang a little patch of a headsail out of a furler in blustery conditions, but it’s so easily done and with the wind up, the shape matters a lot less.

I mostly like to go out in calm seas because why not try to plan passages to be comfortable?

This means lighter winds by definition so I’m usually struggling to get more sail area up.

It’s hard to see the purpose of the little self tacking jibs. Should I just skip that setup on my new cat?

[fxykty]

Originally Posted by Chotu

Starting to wonder. Why DO we have these little self tacking jibs at all when a screecher and asymmetrical spinnaker can be set up on furlers?

I had a cutter rig on my old gulfstar and used the similar staysail a grand total of never.

I realize the shape isn’t perfect when you hang a little patch of a headsail out of a furler in blustery conditions, but it’s so easily done and with the wind up, the shape matters a lot less.

I mostly like to go out in calm seas because why not try to plan passages to be comfortable?

This means lighter winds by definition so I’m usually struggling to get more sail area up.

It’s hard to see the purpose of the little self tacking jibs. Should I just skip that setup on my new cat?

Well, a decent performance cruising cat, especially with a high aspect ratio rig, generally does not need a lot of sail area to sail well. In lighter winds (say <8 knots TWS) more sail area is needed to achieve good VMG upwind, hence a screecher or J0 is useful. If you have an overlapping genoa that may be plenty except in really light air.

The beauty of a self tacking jib is from the mid range and up of full main, one reef and second reef. Same head sail and no furling (reefing) to wreck the upwind shape for that entire range. Easy to manage, no hassles to tack or gybe, more than enough power with a relatively small sail area.

Moderate and heavy displacement cats need more power, therefore more sail area from an overlapping genoa, throughout their range. A screecher might be useful in lighter winds, but in higher winds the full genoa will be needed well into the first reef of the main - provides sail area for power and a lower centre of effort.

It all depends on your boat and on how you want to sail. But do remember that you may plan your departure for light winds and calm seas, but a few days or week later that forecast may no longer be correct and it may not be so calm.

If you do need to go upwind, a larger sail furled more than 25% will have a lousy shape with much more drag than a smaller sail that isn’t furled. Other than close hauled that doesn’t matter, so if you follow the “gentlemen don’t sail to windward” ethos then you don’t need to worry about it.