Friday, March 1, 2013

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:

Meet the Byte CII, the Next Great Singlehanded Class:

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