by: Henry Bossett - Decmeber 10, 1984
Speed in a DN is produced by a combination of the following factors: Runner Alignment, Runner type, Plank type, Mast/Sail/Boom type, Hull type, Tuning factors and Sailing technique. An adjustment to anyone of these areas.will have an affect on the performance of the boat and your final position. Each of these areas is important and large enough in scope that you must study and understand them individually, before you can hope to improve your results.
My discussion is going to be about Runner Alignment. Even if you have achieved perfection in all the other areas, improper alignment can actually keep you from sailing around a course, let alone trying to win a race. Everyone seems to have his own idea of how best to align their runners. To discuss them all would fill a book, so 1 will just relate the various areas that I check to be sure of my alignment.
The first step is to get your chocks set up on your plank so that they are parallel and capable of moving enough to align your runners. Thus, although it would be nice to just drill exact size holes for your bolts, it is better to drill oversize holes. You do not need a fancy set up to do this. Simply drawing a line across the plank end at the bolt hole locations with a carpenters square placed along the front or back aide of the plank will do. If the mounting surface on the plank is uneven you will have to smooth it with an additional layer of wood or epoxy with filler. The point here is to be sure that both the left and right surfaces are parallel to each other. If not, then your runners will change alignment as the plank bends, check for this with an adjustable level. Look at both the fore and aft direction and sideways.
Next you need to take a good look at the actual edge of your most reliable set of runners. Use these to align your chocks since they will be from front to back. It may be straight for a short distance under the pin, but most that I have checked will then wander to one side or another at the front and back. Usually the edge will also not be aligned perfectly with the stiffener. This is why you have to shim each set of runners individually on a given plank (unless you machine your own runners and have built them to perfection). I started using a small rifle scope three years ago, and was amazed at how far the edge wandered. I am not convinced that this degree of perfection is needed, but it is just one more tool that I use to be sure of proper alignment.
Once I am sure of a good edge on my all around runners, and have drilled the holes in the plank for the chocks, I drill a lot of small holes into the flat surface of the chock to help it glue to the plank. These are randomly spaced, and I also rough up the surface with harsh sandpaper. Now when you glue your chocks on (the only way to be sure of continued alignment throughout the season), they will have a very difficult time breaking free. When I finally mount the chocks, I fill all the holes with a mixture of "Gougeon" and filler, plus spread a small amount on the entire surface. This mixture will bold your cbocks in place until YOU. decide you want to change them.
I align my runners using triangle plates. The plank is mounted on the boat, and weight is put in boat to approximate my weight, the rig weight, and a small amount of downthrust such as a sma11 puff would generate. This all makes sure that I am in the most perfect alignment when the boat is coasting. It is at this point that both runners are firmly planted in the ice and thus need to track together. Any more wind and your windward runner starts to get light and alignment becomes less important.
The triangle plates that the runners sit on have their runner supports only 10" apart so that any bend in the front or back of the runner will not result in bad alignment. After all, that is the portion of the runner' that is most deeply imbedded in the ice. Plates seem at first to need machine sighting thru string set up as a large "T" on the floor, using the easy method of swinging two arcs to get the right angle "T". I then glued the supports in place and after they dried, screwed them in place for added safety. It worked perfectly, since anyone who uses my plates seems to glide quite well.
The fina1 step is to check it all on the ice. On those no wind days when most everyone is sitting around the bar waiting for the wind to come up, you will find me out on the ice "Test Gliding" my boat. You need near perfect ice to do this, but that is what we usually have at the beginning of the season anyway. Push your boat up to speed, then hop in and listen to it, as well as watching the runners. If you are out of alignment, the runners will be pulled further out of alignment and then spring back with a scratching noise severa1 times during your Glide. In springing back, they will throw ice chips, and this will tell you if you are toed in or out. Use thin shims to finally align them to the point that the boat glides further and is quiet. Now you are finally ready to beat the pants off of your buddies when they finally get back on the ice after all their Elbow exercise.
The one thing that bas become apparent in all the work that I have done to make my boat fast is that if you use your own senses and do not worry too much about Space Age Technology, you WILL. be fast. Don't get me wrong, you do have to investigate everything that promises to be a breakthrough, but the biggest breakthroughs in your own performance will come from straight forward practice, and keeping your eyes and ears open to what's right there in front of you. Good Luck this Season!