@jimmybeast - Syncing Your Sail Trim and Bridle Height

One of the most overlooked adjustments in Club 420 sailing is the bridle.  Admittedly, it is not as important, especially over short distance races, as your basic tuning adjustments (mast rake, vang, cunningham, etc.).  College sailing teams don’t even have the adjustment on the boat, in an attempt to simplify the boat for short distance racing.  However, knowing how to properly adjust the bridle on the Club 420 will not only give you a tuning advantage on longer courses, but will better prepare you for understanding sail shapes when you transition into other high performance classes down the road.

Overview:

Above all else, you must have the bridle set up so that it is center lined at all times.  Having it set even a few centimeters off, in one direction or another, will seriously jeopardize your ability to sail fast upwind.  Before you hoist your sails, pull the bridle forward along the centerboard.  Make sure, when pulled taught, that the block on the bridle is perfectly centered in the boat.

The purpose of the bridle is to enable sailors to obtain the ideal mainsail shape, while keeping the boom in the center of the boat, as you sail upwind.  As you pull in the mainsail, you not only move the boom towards the center of the boat, but you also pull downward on the boom.  The further down you pull the boom, the more tension and power you put into the leech of the sail.  Thus, the higher your bridle is, the earlier the blocks all come together, the less you pull down on the boom, and the less tension you are able to apply to the leech.  In other words, a higher bridle will yield a center lined boom with less leech tension (more twist) on the main, and a lower traveler will yield a center lined boom with more leech tension (less twist) on the main.

Light Air:

In light air, you want the ability to center line the boom, keeping the flow off of the jib from interfering with the mainsail.  At the same time, you want to avoid putting tension on the leech that will stall the main and slow you down.  Thus, you want to raise your bridle to the point where, when the boom is center lined, your leech tell tail is streaming back 50% of the time and disappearing 50% of the time.  Leave about two inches of trim between the blocks on the bridle and boom so that you can add a bit more leech tension in puffs around the course.

Medium Air:

Tuning the bridle in medium air is dependent on how you define medium air.  In a Club 420, you have the ability to trapeze, which considerably increases the wind ranges that you are able to sail in.  For the purposes of this article, medium air is defined as any wind speed, other than light air speeds,  where you do not have to dump the main, or you seldom have to dump the main, in order to keep the boat flat.  This range can cover anywhere from 8-15+ knots, depending on the size of the sailors in the boat.

The point is, as the wind increases, up to the point where you start to get overpowered, you will want to increase the power and pointing ability in your boat.  This is accomplished by trimming the main in harder, which will apply more tension to the leech of the main, the bend in the mast, and the luff of the jib.  If your bridle is set too high, you will end up block to block too early, and won’t have the ability to get the desired amount of leech tension when your boom is center lined.

Ultimately, the same concept applies in both medium and light air.  Your goal is to get the boom as close to center lined as possible, while applying the desired amount of tension on the leech of the main (50/50 rule on the top batten tell tale).  Always leave a couple of extra inches, just in case you need a touch more trim in puffs.  There is the widest range of adjustments to the bridal in this wind range.

Heavy air:

As you start to get to the point where you are overpowered, you will want to start raising the bridle again.  As you start getting overpowered, you will need to apply more vang, and dump the main to keep the boat flat.  The more you dump the main, the more it will affect the slot (the gap between the main and jib).  While easing is necessary, you want to ease while having as small an impact as possible on the flow over the jib.  Thus, by raising the bridle, when the sail is trimmed to centerline, you will not have the ability to apply much tension to the leech.  In other words, your sail will reach the centerline with more twist in it, spilling excess breeze out of it, allowing you to depower more with the boom in the ideal position.  With the right amount of vang on, the boom will just go outboard from there when you ease.

Summary:

How you use the bridle will depend significantly on your weight range, and the conditions.  The important thing to understand is that you ideally want your boom in the center of the boat at all times, when sailing upwind.  Depending on where you set the bridle, when the boom is center lined, the main will have more or less tension on the leach.  The more you want the leech to twist off (i.e. windy or light winds), the higher you will need your bridle.  Likewise, the more you want to take the twist out of your sail (i.e. medium winds), the lower you will want to set your bridle.

See you on the water,

Zim Coach

Tracking Upwind in Waves

Have you ever gone over the top of a giant wave, and felt the boat slam down violently as you crossed over it?  It happens all the time in boats of all sizes, and is called hobby-horsing.  No matter how big or small the wave is, not having the ability to prevent your boat from doing this is will slow you down significantly.  The opposite of hobby-horsing is called tracking.  Tracking is the act of keeping your fully in touch with the water at all times, with no bow slamming or vibrations moving through your hull.  The smaller, lighter, and less stable a boat is, the more important tracking through the water is, as these boats will slow down much more quickly than large, heavy, and stable boats.  By keeping your speed up, helm neutral, and using precise steering and/or trimming movements, you can increase your ability to track through the water, and put miles of boat speed on your competition.

Steering & The Boat’s Ideal Path Through a Wave:

Waves are your best friend downwind, and your worst enemy upwind.  Upwind, not only does a wave serve as a roadblock, but is also a strong natural force that pushes your boat sideways.  The more the wave moves toward your boat from the side, the more susceptible your boat is to a sideways slide.  This makes you generally slower, and crushes your ability to point or hold your lane.  However, with the proper technique, this is something you can use the waves as an asset when sailing upwind.

When trying to track effectively through the water, each wave you sail through has an entry phase and an exit phase.  The goal in the entry phase is to minimalize the amount the wave can push you sideways. The goal in the exit phase is to keep the boat from hobby-horsing, and to power up again for the next wave.

Entry Phase

As you are about to enter the face of a wave, you need to steer up, and into the face of the wave.  The amount you steer depends on the size of the wave.  The smaller the wave, the less you turn the boat.  The larger the wave, the more you will turn the boat.  This will align your bow more directly and head-on with the wave in order to punch through it, effectively reducing the amount the wave can push you sideways.  Ultimately, you want to give each wave less direct surface to push sideways.

Exit Phase

When you turn into the face of a wave, you will reduce your speed at the top of it, making you much more susceptible to hobby-horsing.  To correct this, you must turn hard and quickly down the back side of the wave to keep the boat in touch with the water, and to increase your speed before the next wave.  Depending on the wind and waves, you may even want to exaggerate the turn over the wave, steering slightly past a close hauled course.  You should only do this for the most brief instant, and then return to a close hauled course to get ready for the next wave.

Steering:

One of the first racing principles sailors are taught, is that using the rudder is slow.  While this is true, hobby-horsing is much slower than using some tiller to steer through waves.  An alternative to using tiller is changing sail trim during the entry and exit phases.  Some sailors will trim during the entry phase to steer up, and ease during the exit phase to steer down.  In all boats, you will see some combination of steering and trimming to effectively steer through waves.  The exact ratios will depend on the conditions, your relative weight range for those conditions, and the type of boat you are sailing.  As a general rule, steering with the sails is more effective in doublehanded boats, while steering with your tiller is more effective in singlehanded boats.  Again, usually there is a mixture of both.

Neutralizing Your Helm:

Having a neutral helm will make your boat much more receptive to changes in steering or trimming.  Let’s consider a boat’s ideal path through a wave.  There is actually a relatively large amount of steering that is necessary to keep the boat tracking through the water, regardless of your speed and power.  If your boat is heeled to leeward at the top of a wave, giving you weather helm, then you must use a good deal of rudder, or ease the sail significantly, to turn the boat down the backside of a wave.  Thus, keeping a boat flat with a neutral helm, at the top of a wave, is critical to keeping the boat tracking through the water.

Maintaining Your Speed/Power:

Speed and power are essential to tracking through the water.  When you encounter a wave, slowing down, or entering the face of that wave with little speed or power will make it difficult to get over the top without getting pushed sideways, causing your bow to slam down on the other side.  When you move from wave to wave, the goal is to maximize your speed before the wave, use that speed to reach the top of the wave, and then quickly build it up again as you descend and move on to the next wave.  This takes a lot of intense focus and practice to perfect, so go out and start practicing!

See you on the water,

Zim Coach  

Depowering the Byte CII Upwind

The Byte CII is a boat that is growing in popularity both nationally and internationally.  This is the second year in a row that it will have a fleet in two US Sailing National Championships, the US Women’s Singlehanded Championship and the Chubb US Junior Championships.  It will also have a fleet at CORK OCR in Canada, followed by the Byte CII World Championship in Newport, Rhode Island at the end of August.  While the boat resembles a typical singlehanded dinghy in many ways, because of its high performance sail and mast design, it is much different in terms of how the boat is tuned than any other typical dinghy found on today’s market.  This will leave a lot of opportunity, for those who learn how to tune the boat effectively, to overwhelm the fleet with superior speed.

One of the most unique tuning differences between the Byte CII and any other typical dinghy is how you depower the boat upwind in breeze.  To understand why you depower this boat so differently, you first need to understand the boat’s sail and mast designs.  The mast is tapered and made of carbon fiber.  This makes it extraordinarily light, allowing increased and progressive flexibility in the mast.
 
Additionally, the sail is fully battened and made of Mylar as opposed to the traditional Dacron found on virtually every other dinghy.  Mylar does not stretch like Dacron, and is both stronger and more durable.  The battens stretch across the entire sail as opposed to simply supporting the leech, as seen on most traditional dinghies.  When you combine these factors you are capable of inducing significant mast bend without stressing the leech.  This is not possible on any of the traditional one person dinghies in the world, which need significant stress on the leech, via the vang and mainsheet, in order to bend and depower the mast.  The end result is a highly tunable sail plan that more accurately simulates the tuning adjustments of the most high performance boats around the world.

When you sail a Byte CII in heavy air going upwind, instead of using the vang to flatten and depower the sail, your first line of defense is the cunningham.  Because of the design, as discussed earlier, pulling on more cunningham will allow you to bend the mast progressively backward and to leeward, facilitating twist.  Thus, putting on vang or trimming hard on the mainsheet will only take that twist out of the sail, and will power you up when you are attempting to depower.  Thus, by using only the cunningham, you are capable of inducing full mast bend with no tension along the leech.  As you do sail upwind, you should simply snug up the vang so that it has no slack dangling when you are trimmed in.  This will allow you to ease the main out without having the boom move upward, which would alter the sails shape.

The second major adjustment for upwind sailing is the traveler.  The traveler on the Byte CII is set up on two cars, so that it is easily adjustable on each tack.  To understand the traveler’s importance, you need to know that the boat is fastest when the sail is trimmed over the aft leeward corner, just like traditional singlehanded boats.  As you depower using the cunningham, the boom will move further out and away from the corner.  What this means for the Byte CII is that you must pull the boom back over the corner when you put on cunningham, but no longer need to pull in the main sheet hard to do so.  Remember, when you are trying to depower upwind, the tighter you pull your mainsheet, the more you apply stress to the leech, and power the boat up.  While mainsheet is necessary to have on every boat, the Byte CII is set up, so that you can trim the mainsheet to the proper place without bending the mast or tightening the leech.  Thus, in heavy air, by pulling the windward traveler car to windward, you can get the boom to the corner while using less mainsheet.  The boat is as depowered as it will get when the cunningham is fully on, the traveler is fully to windward, and the boom is over the corner of the stern.  When you drop the traveler car to leeward in breeze, you will have to compensate with the mainsheet to get the sail over the back corner and maintain your pointing.  If it is windy enough that you need to depower the sail, this is not ideal.

Photo Courtesy of Sailing Scuttlebutt

If you are still overpowered after using all of these adjustments and the outhall, which is a much more straight forward adjustment, the last step you can take to depower the boat is to start raising the daggerboard.  For lighter sailors, this can happen as early as 15 knots.  Start by raising the board an inch, but as the wind continues to increase, raising the board as much as three inches will help depower the boat and reduce the helm.

Properly adjusting these settings is critical for achieving a neutral helm in the Byte CII.  Having a neutral helm at all times will make it exponentially less difficult to steer the boat through waves.  While this is important in all boats, it is even more so in the Byte CII.  Weighing only 100 lbs., it accelerates quite rapidly with this advanced rig.  However, like all boats that accelerate quickly, it decelerates quickly too, which will occur often if you stick the bow through a wave or slam the bow down after you cross over a wave’s crest.  Thus, if you do not neutralize your helm, you will have a particularly difficult time steering down waves upwind, and you are going to struggle to have success upwind in the Byte CII.

This is the first of many articles that I will release on tuning and sailing the Byte CII, as we progress towards the World Championship.  If you have questions about sailing the Byte CII or anything else, tweet me @zimsailing using the #zimcoach!  I will be happy to answer them!

See you on the water,

Zim Coach

More Info on the ByteCII and the Byte CII Worlds:

Byte CII Worlds NOR: http://bit.ly/ByteCIIWorlds

Meet the Byte CII, the Next Great Singlehanded Class: http://bit.ly/ByteCIIS1D