Perhaps one of the toughest points of sail to master for sailors new to the A-class and uni-rig catamarans is downwind in light air up to the point where you start thinking about making the transition to the “Wild Mode”. With no jib in front of the main, it is important to learn how to trim and steer the boat not too deep or too high for the best VMG.
I’ve had some excellent tuning partners, competitors, and teachers over the last couple of years including Ben Hall, Pete Melvin, Bob Webbon, and Charlie Ogeltree. Here is a summary of setup and technique I’ve learned and currently use:
Downhaul – completely off (very important), slight wrinkles showing
Outhaul – ease off to the point where you have at least 6” – 8” of maximum foot camber, sometimes more or less is better dependent upon the how light it is and how smooth or choppy the water is. Once you establish the maximum setting, it may be helpful to put in a stopper knot or ball on the outhaul control line so all you have to do is blow the control out of the cleat as you round the weather or offset mark.
Mast Rotation – You should have a system that will allow at least 90 degrees of mast rotation since this is the approximate apparent wind angle you will be sailing downwind, more is better in this case.
Traveller – The position of the traveler can vary between all the way out to 4”-6” pulled in. This can depend upon the water conditions. In flat water, it can work to let it out all the way. In choppy water, it can work to pull it in 4”-6” and ease the mainsheet tension to get more twist in the sail.
Mainsheet tension – Most sailors set the mainsheet tension and cleat it and then focus on steering the boat. A good indicator is the set of telltales placed in the top third of the sail. You probably want enough mainsheet tension to firm up the leech and not stall the top leeward telltale.
Weight Distribution – For the Boyer boats (Mk. IV, Mk. V, and Flyer), I believe it is very important to sit right on the weather front beam or even better right in front of it. This is probably also the case with the new Bim XJ. You can typically sit just behind the front beam on the Marstrom and A2 boats. What you are looking for is to be sure the transoms are not dragging (the transom wake should be clean and quiet, no gurgling). Moving 12” forwards or backwar ds can make a significant difference. It does not seem to work at all to sit forward on the leeward side of the boat. This only creates more wetted surface area and drag.
Daggerboards – both boards max up (but make sure some amount of board is filling the bottom of the daggerboard case)
Rudders – Most sailors will sail with both rudders down but several of the best sailors in the class feel there is a slight speed advantage to sail with one rudder kicked up. Practice this because if you are sloppy or jerky getting the rudder up or down, you could lose more than if you did not do it.
As you round the weather mark, follow this list to transition the boat from upwind to downwind modes:
Steer to your downwind course as you ease the mainsheet and traveller, settle the boat down for 5 seconds.
Release any downhaul tension and rotate the mast to 90 degrees or more.
Pull up the weather board.
Pull up the leeward board.
Raise the windward rudder.
Once you get the boat setup and on course, you need to get into a fast steering groove. You will probably not be consistent if you try to steer the boat by just the telltales in the mainsail. Most sailors have telltales on the forestays and or a telltale or Windex on the front of the mast. Either way, you want to create a consistent reference that you can steer up or down to and maintain a consistent “groove”. On my boat, I put a telltale on each forestay at the height of the spreaders. I use the angle between the weather telltale and the rotated leeward spreader as my steering reference. I like the reference this high as it indicates the true wind more accurately. I glance up at it about every five seconds and check the sail trim also. I try to combine this reference with the feel of the wind blowing across my face or the back of my head. Looking forward, if I feel the wind starting to blow on to the front of my face, I can probably steer down. If I feel the wind starting to blow more on the side or back of my head, I will start to steer up.
Steering technique is very important. The less you move the rudders, the faster you will be. The steering technique I like is to have the tiller extension across the front of my body with it propped on my leg or knee. This creates a hinge point where I can simply flex the tiller extension back and forth with my wrist to steer very smoothly up or down.
A new tool I have been using since the 2004 North Americans is a “JC” strap. The name comes from the shock cord system used by the Finn class to hold their booms out as they sail downwind in light air. If your boat has the standard downwind rotator like that supplied by Boyer and also on the A2, sailing in sloppy water allows the mast to pump back and forth which is not good for maintaining flow across the sail. In very light air, you frequently have to put your foot against the mast or boom to keep it at max rotation and quiet. The “JC” strap system is extremely simple. I tie a bullet block to each forestay tang. I next attach a line with two small loops in it right behind the outhaul cleat on the boom. I install a plastic clip on one end of the shock cord, attach to one loop on the boom and then run the shock cord forward through the bullet blocks on the tangs and back to the other loop on the boom. Pull the shock cord relatively tight and attach another plastic clip to attach to the remaining loop on the boom. Without the mainsheet attached, you will find that the shock cord at tension actually pulls out and up on the boom. I have found the tension of the shock cord effectively holds the rotation in place and does not allow it to pump back and forth if the boat rocks. An additional benefit is realized when you gybe as the shock cord speeds the rotation of the rig. The system in no way gets in my way or affects the sailing of the boat. I don’t think the system creates any significant drag or windage. Since I have been using it, I feel I have been consistently faster on downwind legs. Winning the light air race at the 2004 North Americans was proof to me that this system has some merit. It only costs about $20 to install on the boat which is a much cheaper alternative than going to another system to lock the rotation.
I hope these tips help you find more downwind speed. Now get out on the water and start practicing!