full batten sails

[peter north]

What are the pluses and minuses of fully battened mainsails? I'm looking for used sails for my 45' cruising ketch project, and there's one available that's full battened. Any help greatly appreciated.

[Jay Greer]

Strange how long it takes for an old idea to become new again! Actually the Chinese invented full batten sails over a thousand years ago. And L. Francis Herreshoff experimented with them prior to WWII.
So far as efficency is concernerned a full batten sail is more prone to hold shape in light airs and can be more efficient than other forms of sail construction. When coupled with a good set of lazy jacks the sail will drop like a set of Venitian Blinds on top of the boom. Reefing can also be easier because of this. Certainly greater roach can be built into a full batten sail, which will improve down wind performance.

The draw backs are that there is a tremendous amount of force generated between the leach and luff and if the mast is not designed to bear the extra load, there will be problems along the track. Extra weight aloft is another consideration. However, I personaly like full batten sails and have used them on many boats I have designed or built.
JG

[Ian McColgin]

I love fully battened sails on a marconi rig and made a fully battened foresail for Granuaile that was a huge success. So much so that the best Marco Polo in the universe, Star, got all three sails made such. It turns the sometimes, well never slow but shall we say, deliberate boat into something a bit perky.

The high roach is easily carried way up in the Marco Polo because the back stay for both main and fore come back to the spreaders of the mast behind and thus the space between spreader and mast is huge. Lots of room for a big round peak almost like the unstayed masts (see Ocean Planet) can get.

But even without huge upper roach, the fully battened rigs' advantages often outweigh the disadvantages of weight and cost. Cost is major by the way. There are all sorts of inferior cars for taking the load those long battens impose against the luff sliders. In fact, all examples of fully battened mains I've seen that were unhappy were due to just this. Haarken is not the only successful brand, but basicly all the good ones cost about that much. The hardware people who actually know what they are doing have size ranges to which one might with profit attend.

The sails are quieter in that they just don't luff hugely. They are stronger. Given that batten tension is controlable, they are even more adjustable than a gaff rig.

Trimming is a little different as they are not so happy with twist in the sail. Try to have a nice long traveler and, when on the wind, set it out to the gunnel far more than you'd do with a normal sail. As you get off the wind, vang it hard. Control the draft with luff, foot and batten tension more than with boom lift.

Interestingly, the extra sail area aloft does not add heeling moment. Perhaps this is because the better airfoil aloft has enough forward and even up vector. Perhaps it's because the air foil is more constant to the wind, not over sheeted low and undersheeted high. Similarly, the sails do not add weather helm, maybe even reduce it a tad.

Battens started as a way to get "free" - unmeasured by racing rules - sail area. That's still their main value in gaff rigged boats and many cruising boats. Frankly, the slight performance penalty of going with an unbattened hollow roach is worth lots many traditional ketchs and schooners. This is less true in sloops and yawls unless they are real traditional low aspect (under 3:1) sails.

But a marconi or especially an unstayed boat that's going to be sailed hard and far can really benefit from a properly thought out high roach (if possible) fully battened sail.

I'm a fan.

G'luck

[brian.cunningham]

Originally posted by Ian McColgin:
Interestingly, the extra sail area aloft does not add heeling moment. Perhaps this is because the better airfoil aloft has enough forward and even up vector. Perhaps it's because the air foil is more constant to the wind, not over sheeted low and undersheeted high. Similarly, the sails do not add weather helm, maybe even reduce it a tad.
OK, that I didn't realize.

All the multihulls I've been on have fully battened sails. Due to the speed they get, they like thier sails flatter. I even know one owner that has a fully battened jib, obviously not on a roller.

Here's a racing schooner with battened sails

http://www.northsails.co.uk/media/articles/images/windrosetunnel.jpg
http://www.northsails.co.uk/media/articles/images/windrose2.jpg
http://www.northsails.co.uk/media/articles/windrose.html

[ 02-05-2006, 09:56 AM: Message edited by: brian.cunningham ]

[Patrick Miller]

I'm a great fan of fully battened mainsails. I fitted one from a Lightweight Sharpie racing dinghy onto my little 20' wooden boat and found I got a lot more power from the increased roach.

One problem(?) I hadn't counted on though. It was very quiet when luffing and had a tendency to keep the boat sailing when I really wanted to stop. The first time I tried to shoot up to my mooring I used my usual method of just pointing into the eye of the wind, letting go the tiller and scrambling forward to grab the buoy as the boat slowed to a stop. But the boat developed an amazing knack of sailing off on its own! I eventually learned that the angle was critical. You have to be dead to leeward and luff up dead to windward. Even then, the sail will retain a power shape and you'll have to stay on the tiller much longer making sure she doesn't fall off and start sailing. Oh, but I did find out that pushing the boom out to windward was a fantastically effective hand brake. My upwind approach to my mooring or a jetty changed so that I approached at a greater speed, then pulled on the hand brake, then let go of the tiller and did the mooring thing. Easy peasy.

Heaving to was also a bit hairy because she used to fore reach at about a knot and a half - I never did find the balance point that allowed me to sit with just enough speed for rudder authority.

Yep, a fully battened main with a bit of roach to it is a going sail, not a stopping one.

[ahp]

Works even better if you have a rotating teardrop section mast.

[Todd Bradshaw]

Yes, just about all of the information posted above in favor of fully battened sails can be true - but - it's not quite as easy as the posts above would make it seem and fully-battened sails are nowhere near as generic as one might believe as a result of reading those posts. You don't just hang up any fully-battened sail with a big roach and instantly go fast. They can just as easily be a totally incorrect and ineffective solution for your particular boat and cause you to go slower or rob you of the power needed to drive your boat through a chop. It would also be quite possible to buy a sail designed to perform and work best at hull speeds that your boat can never achieve. The big roach is also very capable of totally screwing up the balance of your rig and hull on certain points of sail. If you're looking at buying a used one, it would be a very good idea to look for one designed to be used on a very similar boat to the one you intend to use it on. Failure to do so may cost you a lot of performance.

One problem is that most fully-battened sails aren't particularly adjustable in use, shape-wise. Depending on the cut and materials, they may not be very adjustable, period. The shape is often cut and sewn-in and what you see is what you get - and all you get. Most of these sails are computer plotted these days and the computer wants a lot of information before it designs the sail. Much of this will be specifically tailored to the intended hull. The draft amount and it's placement fore-and-aft, the upper sail twist amount and the luff's entry angle and how sharp, steep or rounded it is will all be pre-determined and adjusted for that particular type of boat and it's sailing characteristics.

For example, if we wanted to put fully-battened mains on a couple generic boats - say a beamy cruising monohull and a fast, daysailing racer or even more extreme, a quick multihull, the values entered for all those specifications would be very different. The fast boat would likely have a somewhat flatter than average main with it's draft moved forward. You're probably looking at something with draft in the range of 1:15 (one foot draft for every 15' of chord width) and the maximum depth could be as far forward as 35% of chord width aft of the mast. It could have a round-ish entry curve to help keep it from stalling out and be designed to work best at high speeds where the aparent wind is often shifted pretty far forward due to boat speed. Essentially, this boat may be sailing much more of the time as if it's close-hauled (and things like sheeting tension and sail twist will be set that way) even if it is not really on a typical, close-hauled course with regard to the actual wind direction. The aparent wind is the one that's affecting the sails and the one they will be designed and adjusted to work in.

A sail of the exact same area, aspect ratio, roach amount and profile, but cut to fit our fatter, slower cruising boat, will usually have a very different shape when it comes to all those little computer values. Draft is more likely going to be more like 10:1, rather than the 15:1 used for the fast boat. It will also be placed somewhere around 45%-50% of chord width aft of the mast. So, right off the bat, we have half again as much draft depth and it may be up to 15% farther aft. This is to generate more power and is done at the expense of potential high speeds. Fatter boats need more raw power to push them along and through waves than lighter, faster boats which accelerate quickly. They will never be as fast, so a sail designed to do 20 knots with the aparent wind shifted far forward will never be an appropriate choice for the fat boat.

We can build both these sails with the same panel layout, same fabrics, same trim options and they would be hard to tell apart at first glance - but mix them up and put them on the wrong boats and both hulls are going to sail like crap. The slow boat isn't going to have the power needed to push it properly and the fast boat will soon reach the upper speed limit of the fat boat's mainsail and find that it no longer has high gear available to really get moving because it's stalling out all the time.

Things obviously aren't always this extreme or cut and dried. There is always a chance that you could buy a used sail that worked reasonably well on your boat, but you need to be aware that your cruising monohull still needs sails designed for a cruising monohull, not a set that came off of a racing trimaran that weighs 30% as much, comes up to speed with a less than half of the brute force and goes two or three times as fast. In any case, just adding any old full-batten main that seems to be about the right size to fit the boat is not an automatic success and could quite possibly be an expensive mistake.

[ 02-06-2006, 03:50 AM: Message edited by: Todd Bradshaw ]

[RodB]

My experience in this venue is with sailboards and I remember when windsurfing was gaining popularity most sails migrated towards the fully battened designs and they pretty much dominated most sailing events from then on....except in very light airs, the unbattened sail was able to eek out just a bit more power compared to the fully battened...creating a fuller luff...

Sailboards were a great craft to perfect sail designs and progressed fantastically over a few years in the beginning. Now improvements are in much finer increments.

RB

[Ian McColgin]

I am glad that Todd clarified the importance of cutting a fully battened sail in a manner appropriate to the boat's predictable speed.

There now is quite a lot of technical information available and there's no excuse for an inappropiately cut sail, certainly not for the disasters that occurred twenty years ago when one of my friends actually got better performance from a battenless roll into the mast unit (40' husky cruising sloop) than he'd gotten from the previous fully battened sail. The only good out of that deal was that I bought his car and battens when I went to make my own much more intelligently designed foresail.

You can't just put sleaves in a regular sail, ram a bit of pvc pipe in, and call it a fully battened sail. These modern units have not even a superficial resemblence to the chinese fully battened junk sails - which is why they need no yaloe.

[Andrew Craig-Bennett]

Originally posted by Jay Greer:
Strange how long it takes for an old idea to become new again! Actually the Chinese invented full batten sails over a thousand years ago. And L. Francis Herreshoff experimented with them prior to WWII.
So far as efficency is concernerned a full batten sail is more prone to hold shape in light airs and can be more efficient than other forms of sail construction. When coupled with a good set of lazy jacks the sail will drop like a set of Venitian Blinds on top of the boom. Reefing can also be easier because of this. Certainly greater roach can be built into a full batten sail, which will improve down wind performance.

The draw backs are that there is a tremendous amount of force generated between the leach and luff and if the mast is not designed to bear the extra load, there will be problems along the track. Extra weight aloft is another consideration. However, I personaly like full batten sails and have used them on many boats I have designed or built.
JGDunno about the Chinese, or Herreshoff, but here is a Linton Hope sailing canoe from 1911:

http://www.intcanoe.org/icimages/3_bubble.jpg

[ingo]

I have digitised a beautiful film about full battened gaff rigged dinghies ("J-Jollen") sailing in Switzerland in 1939. You need a RealPlayer to watch it:

J-Jollen-film (http://www.yachtsportarchiv.de/filme/J-Jollen.rm)

[Dan McCosh]

I looked into this a while ago, and the advice from the sailmaker was to lengthen the existing battens rather than full battens. The problem I have is the sheer size of the battens on a boat with a 24 ft. boom. This generates cost, weight, and even some hazard of the battens flailing in a squall. The aerodynamic benifits, I think, increase with higher-aspect ratio rig.