Main Sail Round Table

I found this article on main sails by manufacturers of Ulman, Quantum and North Sails very informative. Of particular interest is the discussion on fully batten sails. I put a set on my 35 ft Dickerson and find they hold their shape very well. Now the trend seems to be to have just lower two battens full. Here it is Irish Mist

THE ANARCHISTS ROUNDTABLE
The Mainsail
Around the Virtual Table are:

Dave Ullman Ullman Sails Founder of Ullman Sails, it’s easier to list the things Dave hasn’t won than it is to list his accomplishments. If you don’t know who he is we can’t help you here.

Larry Leonard Quantum Sails The driving force behind the creation of Quantum Sails which has, in a very short time, established itself as one of the premier sail making groups in the world.

Keith Lorence North Sails Keith’s experience includes success in everything from International 14s to Whitbread racers. A longtime sailmaker with Sobstad in rainy Seattle, Keith has come to his senses and relocated to sunny San Diego.

The Mainsail is the only sail that is flown for the entire time on most race boats, and is without a doubt very important to the overall performance of the boat. However, it seems that many people are perplexed when it comes to getting the most out of the main. We’ve asked Keith, Larry, and Dave to put together some ideas about mainsail construction and trim.

Are you making mainsails significantly differently today than, say, 5 years ago?

Larry: The construction of mainsails, at least for the racing market, has changed significantly over the past 5 years. Lighter, faster, stronger, these are the familiar goals to which we all aspire, but are all becoming possible with the development of new fabrics and construction techniques. These techniques, which include adhesives and fibered corner reinforcements, are now producing one-piece membranes as opposed to old sewn paneled technology.

Keith: No, I would say not much.

Dave: Sails are not very different than five years ago.

Ed. Note: The seemingly contradictory answers from the panel are most likely due to semantics, and our arbitrary choice of a 5 year window. Hey, it’s our first Round Table. We’ll get better!

What are the changes? Construction, panel orientation, adhesives, etc. Fuller, Flatter?

North 3DL J-120 Main
Keith: There are subtle evolutionary changes, and two that come to mind are the trend toward less luff curve on flexible rigs. This allows for more roach

within the girth restrictions. The other is the move toward flatter lower sections so that the bottom batten is more open. This is due largely to the fact that modern boats are being designed with bigger mains and longer booms, and less genoa overlap. Longer battens came into play about 5 years ago, so if your sail is older than 5, this would be another change.

Dave: The biggest change is in the materials. PBO and Carbon have allowed us to build sails lighter and stronger. Since the material is stronger and changes less under load the mains can be flatter. The new fibers have less mills of mylar so they shrink less.

Larry: It is now important to consider the structural integrity of the entire piece as a single membrane and not as a group of individual panels. Fabrics have continued to improve through the introduction of new fibers like Kevlar 49, Kevlar Edge, Pentex, and now Carbon. Last year at Key West we introduced a new custom fabric called FUSION TFM. This fabric is a further development of our Q Kevlar line and is easily spotted on the race course due to its gray color. This fabric is the most advanced Kevlar laminate made, but is a custom laminate made only for Quantum by Dimension Polyant.

Quantum has worked hard to set itself apart from the rest of the industry. By specifying warp, fill and X-ply denier and count, Quantum has developed a superior product by creating a more balanced fabric. The gray film has been added as a result of testing that has been done and the

Quantum Fusion Farr 60 Main.

effects of ultra-violet sunlight. This new color is now being emulated by many other sailmakers in the market, including North. Some of these products are achieving the color through artificial dyes, which have no protective qualities, in an effort to duplicate the marketing impact it has had on the market.

Other advances we’ve made in creating distance between Quantum and our competition is in re-engineering the mainsail details and systems. Some of these include a new batten tensioning system, custom head pieces that replace conventional headboards, and fibered corner and batten-end reinforcements. Maintaining batten tension has always been a problem and is critical in sustaining an efficient mainsail shape. Our new system utilizes a 3:1 purchase that guarantees proper batten tension and makes it impossible to lose a batten. The head pieces are custom sized for each mainsail and, with proper attachment, distribute head load evenly to prevent any problem or distortion emanating from the head. Adding to these features, the fibered corner reinforcements provide a light weight alternative to normal corner reinforcement.

Do you prefer Full Battens for the entire sail, or only a couple of full battens?

Dave: A race main with standard race roach should have one full top batten. If the main has excess roach up high, it should have more than one batten in the section

Keith: One full top batten for most racing sails, and as many as 5 other partial battens for the rest. You will see multiple full battens on the extreme types such as America’s Cup yachts, world girdling multihulls, and any mainsail with huge roaches of this type.

For cruising sails, which are typically made of Dacron, I like the full battens. They calm the sail down while motor sailing, and reduce the devastating effects of Dacron stretch. On the downside, some types of masts will have trouble with the batten receptacle to mast joint, causing the slides to jam.

Larry: Batten selection for our mainsails depends on function and is determined by the sailors intended use, including cruising, race cruise, or full race. Listed below are our recommendations.

Cruising: Full battens are standard. The number is determined by the luff length and can include as many as 7 battens, as spacing is kept to an accepted minimum. Full battens provide several advantages to the cruising sailor. Luffing or flogging is dampened, folding and storage is facilitated, efficient sail shape and durability are enhanced, and fabric strength or weight can be reduced as the battens provide additional support and structure.

Full length battens have only become possible as inboard luff systems have been developed to carry the compression load caused by this type of system. Batten tension can be accomplished mechanically, either at the inboard end when using certain end fittings, or manually at the outboard end using our webbing and Velcro system. Tension should be set to eliminate any vertical wrinkles when the sail is fully set and cambered. Careful attention must be paid to the construction of the batten pockets as chafe can occur when running as the battens contact the upper shroud. For chafe protection, the top of each pocket should include a piece of Spectra webbing, sewn the length of the pocket.

Race-Cruise: Two system are available and can sometimes be determined by the luff system provide by the mast or boat builder. We have had success with both, but if performance is the primary consideration, a five batten configuration with a full length top is recommended. This system will provide the most effective sail shape for racing, but will sacrifice some of the durability made possible through the use of full length battens. The use of shorter battens allows for a more adjustable sail shape, critical for obtaining maximum performance.

Race: We prefer a five batten system with a full length top which included the batten tensioning system as described above.

How do you set the batten tension on a Full Batten sail?

Keith: A general rule of thumb is to just compress the wrinkles out of the fabric. When sailing, if there are vertical wrinkles along a batten pocket, compress the battens harder until they disappear.

Dave: The tension controls the draft of the sail. More batten tension and the will get fuller, less tension and sail will get flatter. This is an easy adjustment.

Larry: (Ed. Note: See Larry’s answers to the questions above)

What is the biggest mistake you see people making when trimming the main?

Dave: People tend to over trim mains. The upper telltale should flow 50% of the time.

Ed.: Dave is making a very important point here. In our experience it seems that in most conditions the best height/speed is achieved with the tell tale at the end of the upper batten just flicking between flowing and sucking behind the main.

But what do we know? After all, the Anarchists were recently booted off a 1D48 because the main trim was, according to sources from the boat, “half a knot slow.”

Keith: A couple of big ones are:

Sheet too loose upwind, twisting the top too much,

Sheet too tight upwind, stalling the top batten tell tale,

Too much luff tension, pulling the draft forward too far,

Too much vang tension off wind, stalling the top.

By “stalling the top batten” I assume you are referring to using a tell tale at the end of the upper batten. Can you explain the use of this very important tool?

Keith: Tell tales are either wool yarn or strips of nylon attached to the leach of the main at the end of each batten, and indicate stall or separated airflow. Sheeting the mainsail hard will cause this stall and the strip will curl around to leeward. This will almost always occur at the top batten first. When this happens, ease the sheet until the tell tale begins to stream aft with the windflow. If the sheet is too loose, it will appear to fly normally.

The avenue to correct sheet tension is to trim the sheet in until the top tell tale stalls, then ease slowly till it flies.

Larry: The most common mistake made when trimming a mainsail is the relation of traveler position and sheet tension in different wind velocities. Traveler position, which controls the position of the boom, has a maximum up position, which places the boom on centerline or just above, to a maximum down or the length of the available traveler track.

As wind speed increases, correct traveler location is determined by helm pressure and heel angle. Optimum pressure and angle can be achieved as the wind speed increases by lowering the traveler and boom to a point where the mainsail is no longer full or to the end of the track. At this wind speed, it is important to change techniques, going from a traveler down less twist mode, to a traveler up and twisted mode. So once this condition is reached, raise the traveler similar to light air, with the boom just below center line and ease the sheet, creating more twist, allowing the top part of the mainsail to luff, but filling the bottom portion of the sail, and using the angle of the bottom batten to create the necessary weather helm.

What are the 3 best hints you can give to help people get the most out of the main?

Larry: Upwind: The single most important factor when trimming the mainsail upwind is the angle of the top batten and boom to the centerline of the boat. A tell-tale flown from the top batten is critical in determining this position. In most conditions this tell tale should be flying, or when at target speed, just stalling on occasion behind the leech of the main. Second, sheet tension and the resultant twist are based on sea state, requiring less twist in smooth water and more twist in disturbed conditions. Third, as described above, the position of the boom as controlled by the traveler is an exercise in coordination to be in tune and going fast with the helmsman.

Downwind: There are two distinct conditions in which a mainsail is trimmed when sailing downwind. One in which the mainsail still has attached flow and is producing thrust based on its aerodynamic efficiency and the second when it generates thrust as a result of simple wind resistance. Most of the time the first condition exists, so sheet tension and twist are critical. Travel should be centered and secured, using vang tension to set twist and sheet to set trim. As in sailing upwind, the top telltale should always be flying, signifying attached flow and sheet tension should be just tight enough to keep the forward edge of the sail from luffing. As a reference, when sailing downwind with a spinnaker, the boom should always be beyond parallel to the position of the spinnaker pole.

Keith: Upwind, start by setting the traveler so that the boom points to the backstay, and trim the main in until the top telltale just stalls. This should result in the top two battens being roughly parallel to the boom. Luff tension should be just wrinkles out on softer Dacron sails, and just wrinkles showing on higher performance fabrics.

Downwind, ease luff tension, ease the outhaul, and set the vang to allow some twist at the top batten.

Keith, you have mentioned twist a couple of times. A LOT of people seem to misunderstand what a good amount of twist would be (imagining the leech of the sail corkscrewing to leeward). Can you elaborate on your definition of twist? Typically, how open is open? Do you use the tell tale at the end of the top batten the same both upwind and down?

Keith: Twist is the relationship between the top batten and the boom. A sail would be said to have very little twist if the top batten is parallel to the boom. When the top batten angles off to leeward from parallel, it is said to be twisted or open.

Telltales will help determine how the air is flowing off the leach. As a test, sail upwind and stand behind the boom, now sheet the main hard. The top batten will be angled around to weather, and the telltale will curl around to leeward, indicating stall. Now ease the sheet slowly until the telltale begins to flow aft. The batten should now be close to parallel to the boom, and will have the correct amount of twist.

Dave: Use the leach tell tale up wind. The top tell tale should flow 50% of the time.

Downwind use the vang to kept the upper batten parallel.

What’s the best lesson you’ve learned about trimming the main?

Dave: Not to over trim them. Also to use mast bend in light air to get the main flat enough to kept the main flowing.

Ed.: Always remember that when you grab a handful of backstay the leech will open up, so the mainsheet needs to be re-adjusted to keep the correct leech tension.

Keith: Too many, but a few of the top ones are:

Using telltales to indicate stall,

Using more outhaul upwind than I used to,

Learning to live with a looser luff,

and have the right battens for your sail.

The use of enough outhaul is a particularly important point. Without sufficient outhaul it isn’t possible to get the main to look right at all. We Anarchists generally refer to the “too deep due to too little outhaul” as “return”, that is the battens are pointing too far to windward. Can you expand on the idea of outhaul tension as it relates to the overall depth and the interaction with the headsail?

Keith: The correct amount of outhaul will vary some from boat to boat, but in general most modern boats have narrow sheeting angles. This means that the leach of the genoa trims in closely to the main. An overly loose outhaul will close the gap between the two sails and cause excessive backwind as the wind tries to get through the narrow slot.

A typical range of adjustment for an average 30 footer would go from very tight in winds above 12 knots, to eased off 3 inches from maximum in 4 knots of wind.

Larry: (Ed. Note: See Larry’s answers to the questions above)

For the local sailor, what material would be best to have the mainsail constructed from?

Keith: For racing, smaller boat sailors are well served by a performance Dacron fabric. Bigger, heavier boats see advantages in laminated Kevlar sails.

Smaller and mid size cruising boats typically use Dacron, while the larger cruising boats have the option of going to Spectra laminates to control stretch.

Dave: The best material for the local PHRF sailor is hard finished Dacron.

Larry:

Cruising
Dacron – most durable, inexpensive fabric available. Average shape quality and retention.

Hydranet – Produced by Dimension Polyant. Is a Dacron polyester and Spectra blend. Slightly more expensive but better shape retention.

Performance Cruising
Vectran – A laminate formed by using a Vectran pre-tensioned, pre-preg scrim, incorporating polyester taffeta both sides. Durable, low stretch, moderate cost.

Spectra – A laminate formed by using a Spectra pre-tensioned, pre-preg scrim, incorporating polyester or Spectra taffeta both sides. Very durable, moderate stretch, very expensive.

FUSION TFM – A custom Quantum laminate which incorporates a Kevlar pre-tensioned , pre-preg scrim, gray Magna-shield for UV protection, and polyester taffeta both sides, for abrasion resistance.

Race Cruise
Dacron – Dimension HTP, Bainbridge NYT. These fabrics are highly resinated which produce great shape holding ability. Suitable for mainsails for boats up to 35′. Durable low stretch, moderate weight, economical.

Pentex – A laminate formed by using a Pentex pre-tensioned, pre-preg scrim, incorporating polyester taffeta both sides. Suitable for mainsails for boats up to 30′. Moderate durability, moderate cost, light.

FUSION IFM – A custom Quantum laminate which incorporates a light weight Kevlar pre-tensioned, pre-preg scrim, inserted Kevlar warp and gray pigment to simulate the gray Magna-shield used in our TFM style. Suitable for boats up to 40′. Durable, moderate cost, low stretch.

FUSION TFM Q – A custom Quantum laminate which incorporates a Kevlar pre-tensioned, pre-preg scrim, gray Magna-shield for UV protection. Suitable for boats up to 85′. Very durable, very low stretch, very light, moderate to expensive.

What about for the Grand Prix sailor?

Keith: To compete in the Grand prix arena requires the highest tech sails, most commonly Kevlar. America’s Cup boats are using a blend of Kevlar and Carbon fiber, with the trend moving toward a higher Carbon content.

Dave: For the Grand Prix sailor Carbon or PBO is the material to use.

Larry: FUSION TFM Q – A custom Quantum laminate, which incorporates a Kevlar pre-tensioned, pre-preg scrim, gray Magna-shield for UV protection. Suitable for boats up to 85′. Very durable, very low stretch, very light, moderate to expensive.

FUSION TFM QC – A custom Quantum laminate which incorporates a Kevlar pre-tensioned, pre-preg scrim, inserted Carbon warp, gray Magna-shield for UV protection. Suitable for boats up to 85′. Very durable, very low stretch, very light, moderate to expensive.

Thanks Keith, Dave, and Larry. Sounds like the experts are in agreement on the fundamentals that produce good pace. There are some great nuggets of wisdom here.