@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

The Byte CII Tuning Parabola

The Byte CII World Championship is coming to Newport, Rhode Island this summer, with a host of clinics and regattas leading up to the event.  While many of the traditional dinghy classes rely on the vang to induce and maintain mast bend and a flat sail, the Byte CII does not.  This makes the boat unique in terms of tuning and sail trim compared to the traditional dinghy classes.  To help you train for the Worlds this summer, here is a basic overview of trimming the Byte CII’s sail across different wind ranges.

The Byte CII was specifically designed by Ian Bruce to fit a weight range, as opposed to an age group or gender.  Furthermore, the design is conducive to a large weight range (110 lbs. – 160 lbs.).  The sail is made of Mylar, instead of Dacron, and is fully battened.  When coupled with a tapered, carbon fiber mast, the cunningham carries the load effortlessly to the top of the sail, allowing you to bend the mast and flatten the sail.  What this means to sailors coming from other traditional dinghy classes, is that you never use the vang upwind, because doing so will add unnecessary tension to the leech.  Other traditional dinghies require this tension, as the vang is the only control that allows you to bend the mast and flatten the sail effectively.  This is not the case with the Byte CII. 

The golden rule, for tuning a Byte CII upwind, is to achieve the desired sail shape while keeping the boom over the back corner of the boat.  When applying cunningham, the mast will bend, and the boom will move outboard.  When easing cunningham, the mast will stiffen, and the boom will move inboard.  To counter the boom’s movement from the back corner of the boat, you may use either the mainsheet or the traveler, depending on the wind conditions.

The traveler is the second large game changer from the traditional dinghies.  The traveler’s role in the Byte CII is to allow you to effectively position the boom over the back corner of the boat with the ideal sail shape for the conditions.  In other words, it allows you to effectively control your leech tension for different conditions, via the mainsheet, while keeping your boom in the ideal place for speed and pointing (the leeward rear corner of the boat). 

Thus, in the extreme conditions (light and heavy air), where you generally ease the sheet out, you will pull the traveler to windward, pulling the boom back over the corner to maintain your pointing.  Thus, the sheet is allowing you to control your leech tension, while the traveler controls the sail’s angle to the wind.  In medium air, when you need more power in the sail, and generally would pull tighter on the sail, the traveler drops as far as the centerline of the boat, allowing you to apply just enough tension on the sail to prevent you from spilling much wanted power out of the top.

Because the Byte CII is designed for such a broad weight range, it is important to look at the suggestions below as general guidelines for your level of control upwind.  What a 110 lb. sailor does in 15 knots will vary significantly from what a 160 lb. person will do in 15 knots.

Light Air

You will sail with no cunningham (or just enough to pull the horizontal creases out of the sail), will pull the cunningham far to windward, and will ease the sheet to the corner of the boat.  Your sail will look relatively full, and pulling the traveler to windward will give you more room to ease the sheet to the corner and open the leech.  The tell tale on your top batten should look like it is trying to go forward 50% of the time, and should fly straight back the other 50% of the time (50/50 rule).

Medium Air

As you are fully powered up and under control (butt over the rail or light hiking), you should set the traveler more towards the center of the boat.  You will pull the Cunningham just to the point where you have no creases in the sail.  This will move the boom outboard, and you will compensate by trimming the sail to the corner of the boat.  The 50/50 rule applies here as well. 

Medium Heavy Air

As the Byte CII is a small and physical boat, there is a wind range, where if you hike hard enough, you may want to continue to keep some power in the sail.  For the stronger and heavier sailors, I find this may go as high 15 knots or so.  In this wind range, you will have the cunningham maxed out, the traveler center lined, and the main trimmed to the corner.  If the boat is flat, and you have no helm, this setup will give you tremendous height and power.  This will ONLY work if you are hiking hard, and have no helm.  The instant you are no longer able to maintain a neutral helm, you should start moving to the heavy air setup.  This will happen much earlier if you are sailing in waves and later in flat water.

Heavy Air

As you get to the point where hiking is no longer enough, the Byte CII gives you another setup to keep the lightweights in the game.  Once the cunningham is maxed out, and you start dumping the sail to keep the boat flat, start to move the traveler back up to windward.  This allows you to dump the sail to the point where you are under control, while keeping the sail in the corner of the boat to maintain your pointing.  Without having to use the vang, you are able to do this without applying any tension to your leech, making depowering easy and effective.

The Parabola

Light – Traveler up; sail out; cunningham off or variable

Medium – Traveler down; sail in; cunningham variable

Medium Heavy – Traveler down; sail in; cunningham strapped

Heavy – Traveler up; sail out; cunningham strapped

Byte CII Worlds NOR

Meet the Byte CII, the Next Great Singlehanded Class