To My Friends in the UK I seem to have promised Steve and Simon that I would write an article on tuning a Sonar for your website. Since tuning alone is not enough to be useful, here are some of my thoughts on a number of factors that may improve upwind performance. I hope you find at least some of this helpful. Further, in an effort to counteract the current wave of American tribalism, I welcome any requests for clarification, or other discussion, either on your website forum or by email to info@bostonsailingcenter.com. Sheeting and Steering-Mainsheet and jib sheet trim are the most critical controls. In moderate conditions mainsheet wants to be trimmed so the upper leech telltale stalls about half the time. In light air you may want it to flow most of the time to maximize speed and get the keel working. In very heavy air you may not be able to keep it from flowing full time, which also helps drive through waves. Traveler should be adjusted so boom is on the centerline unless you re overpowered. Every small puff opens the main leech and requires an immediate trim to restore the leech to its critical setting. Every lull requires an ease. Jib should be sheeted so all three luff telltales break at the same time but jib upper leech telltale should absolutely never stall. We do not cleat the jib sheet while sailing upwind, but always work to perfect its trim. In very light air I like to heel the boat to give some shape to the sails. I also drive it to keep the keel working. But as soon as it s windy enough to get three or four crew on the rail it s important to sail as flat as you can. Once you re all fully hiked it s ok to feather to keep it flat, although in chop you have to drive a bit more. I never sail the boat with more helm than you can easily deal with holding the extension with two fingers and a thumb. In breeze I ease the traveler as a shock absorber in puffs and bring it back up once we ve feathered up. In very big breeze we sail with the traveler almost all the way down, mainsheet very tight, and ease the jib in big blasts to help keep the bow up, the helm balanced and the main from ragging. Crew: It is nearly impossible to be competitive through a range of conditions with less than 750 pounds of crew weight. I think 800 is better and Peter Galloway won a midwinter regatta with over 900 once but he was lucky it wasn t a drifter. Mast-we go to great lengths to accurately control the stiffness of the mast so that when you sheet in your main to exactly where you want it to be forestay sag is exactly where you want it to be. This is a critical aspect to setting up a Sonar. Mast stiffness is affected by its age (sorry guys), any existing slop in the spreader-mast connection and the angle of the spreader bar. It s pretty important that the spreader bar be angled so a taut thread across the uppers at the spreader tips is 2 3/4 to 3 from the aft face of the mast. Mast stiffness is controlled by partner blocks and shroud tension.
Turnbuckles- We use Spinlock rigging screws on the forestay and four shrouds. They can be adjusted under load without tools, and they have a built in numbering system (each number corresponds to one turn of the screw) so it is easier to precision tune the rig. Sails- When I had the pleasure of sailing with Steve in early November, we found that when we rigged the old Banks jib with the small tack shackle and large clew shackle provided it was impossible to prevent the top of the sail from luffing. Unfortunately, we did not discover this until the first beat. Sonar class rules allow the lowest point of the jib tack to be 65mm off the deck. This can be achieved with about a 3-inch tack shackle, which you really must have. With a 3-inch shackle and the proper mast rake, the foot roach just scrapes the deck. Also, the clew blocks have to be very very close to the clew in order to sheet in the top of the sail effectively. Finally, I use North sails. Doyle seems to be just as fast and Quantuum is in there too. There may be other manufacturers that are equally tuned in to the Sonar program, but I know these three are fast. Rake-From zero to about 14 knots I set the rake at 25 11. I measure it with the mast down, and engrave the corresponding Spinlock number on the deck. In more breeze I shorten the forestay almost two inches less rake in 25+. That seems to be very fast, perhaps because it enables me to sail with less helm in heeling conditions. Keep in mind that shortening the forestay raises the boom (no big deal in traveler down conditions), raises the jib clew (which may require reevaluating jib lead position) and has the same effect as moving partners forward of the mast (which you want to do as the breeze comes up anyway). Making sure the mast is vertical-with no partners in place, I set the uppers just tight enough to not rattle around and the lowers just tight enough to assure the mast is in column. I use the backstay wire tied to a thin Kevlar line pulled taut to a mark on each toe-rail equidistant from the stem fitting and just aft of the chainplates to get the mast absolutely vertical. I engrave the upper shroud spinlock numbers on the deck. From this starting point, any adjustment to the uppers must be the same on both sides. Tuning- I look at Sonar tune this way: Mast partners control the amount of forestay sag and prebend; Shroud tension controls the life in the rig, i.e. how readily the forestay sags and the main leech opens in response to a puff or wave. The Sonar has an unusually lively rig. I am always striving to find the upper shroud tension that gets the forestay to respond dynamically in rhythm with the waves. That generally means that in light air they are quite loose (maybe four-inch circles in the uppers at rest), and as the breeze comes up they are tightened (maybe as much as 6-800 lbs. by the time it s blowing 25+). In all cases I adjust the lowers while sailing upwind and sighting up the mast to achieve a 1/2 leeward sag at the spreaders. Partner blocks- I use a combination of 1/2, 1/4 and 1/8 Delrin partners. I have found that a 1/8 partner adjustment can result in a noticeable difference in speed. It is important to set up a system so you can move partners easily while racing. We also
modified the angle of the forward inside edge of the deck opening so it is parallel to the forward face of the mast. That keeps forward partners from popping out at random times. Basically, as you add partners behind the mast, the rig becomes more flexible so that for a given main leech setting you get more forestay sag. This gives you more power for light air. Conversely, moving partners to the front of the mast makes it stiffer and de-powers the boat. Because there are many variables affecting mast stiffness (age, spreader slop, spreader angle, precise butt location), information like put 1 5/8 behind the mast with 25 11 rake in 11 knots does not generally translate accurately between boats. However, here are some of the things I look for: Any time you feel you can use more power, more forestay sag is good until either of the following things occur: 1. When the forestay rattles around you have too much sag. 2. When the jib upper leech telltale stalls each time the forestay pumps, you have too much sag. As the breeze increases these symptoms become evident and require moving partners forward and perhaps tightening shrouds too. There is no getting around the fact that you have to learn your own boat. If you can make the time, it is beneficial to schedule dedicated tuning sessions with another boat. Make all initial settings as similar as possible, confirm that main and jib leeches are trimmed identically and that you re sailing at the same angle of heel. Have one boat make one incremental partner adjustment at a time. If it s faster then the other boat matches it. Repeat. Or, while racing, if your boat is set up so that you can move partners without getting off the rail or losing your lane then anytime you are going slower than a competitor in the same breeze try an incremental adjustment. When you suddenly find you re sailing faster it feels very, very good.
Dave Franzel expands on his Sonar tuning guide Following the publication of Dave Franzel's expert advice on fast Sonar settings and techniques, Steve Sleight asked him to expand on a few points. Once again, Dave very kindly agreed and generously shares his knowledge: Q:You refer to very light, light air, big breeze, etc. Can you put some Beaufort numbers around these please? A: You've definitely busted me here for using sloppy terminology. In paragraph 2, the kind of "light air" where you want to allow the main leech telltale to flow more than half the time, and keep the speed up to maximize keel effectiveness rather than trying to point, is any time you have two or more crew inside the boat. (Is that 7 or 8 knots? I'm not sure.) Once three or four crew are on the rail you can close the leech to where the upper leech telltale flows half the time for better pointing. "Very heavy air" where you may not be able to close the upper leech because in spite of everything you might do to stiffen the mast the panel above the hounds stills falls off to leeward might be F5 and up. In paragraph 4, "very light air" where I like to heel the boat to give shape to the sails is anything from zero to maybe 8 kts. "Very big breeze" is the same as "very heavy air", where the mainsheet is on hard, the traveler spends most of its time below the centerline and you have to ease the jib in puffs to keep the main from ragging and to keep the bow up. Q: You talk about rake at 25'11'' in 0-14 knots of breeze then reducing it as the breeze increases up to almost 2'' shorter in 25 knots+. Can you expand on this please? What increments do you reduce it in? For instance, borderline F4/F5 say 17 knots, how much shorter would you make it then? And does it matter if it's flat water or chop? A: I cannot put specific numbers to it. There is no question that rake is fast whenever you can sail the boat flat. There are any number of reasons why this might be: First, it allows you to sail bolt upright without lee helm, second, if you believe in "endplate" effect then both sails are closer to the deck, third, lowering the boom definitely increases the effective range of the traveler which allows you to keep the boom on or above the centerline even when the sheet needs to be eased. I have heard more guesses as to why rake is fast upwind, but empirically, it is. In conditions where you cannot prevent the boat from heeling, however, you will have weather helm with 25' 11" of rake. In chop, where you may want to drive a bit more, you will have to heel more to do that, and less rake will minimize helm under such conditions. I do use the two fingers and a thumb method of determining whether the boat is sufficiently balanced. If it takes more than that to hold the tiller extension then I would consider tightening the forestay more. Q: Your talk about rig tension and a lively rig makes sense to me but both the light air setting (4" circles in the uppers at rest?) and the heavy air 25+ setting of 600-800 lbs seem really extreme compared with the settings used here. We'd typically follow the North/Doyle guides of from 210-300
lbs on the uppers. I'm not sure I could get 600lbs on with the Spinlock screws! Can you explain and confirm your settings please? Also, since you can't adjust rig tension during a race, how do you keep the rig in the boat if you start off with slack uppers and a 20 knot sea breeze kicks in?! A: You're right that if you are set up for light air and a 20 knot sea breeze kicks in you may be at a disadvantage relative to equally fast sailors that are set at 2-300 lbs, although that has happened to me and has turned out to be less of a problem than I expected. While it is a more conservative approach to keep your shroud tension in line with what the sailmakers' tuning guides recommend, I have had success striving to find the shroud tension that gets the forestay pumping in rhythm with the waves. And yes. You can get 600+ lbs. on the uppers with spinlocks if you want to, although I doubt you could if the spreader angle is greater than 3" and you certainly have to chock the mast back (partners in front) as well. Q: The final question (so far!) - how do you adjust your chocks? The idea of being able to adjust them from the rail as implied in your article seems like sailing in heaven to us mortals who have wooden or plastic chocks that are a struggle to adjust! A: I use an old Harken "magic box" screwed into the underside of the deck forward of the raised part of the cabin. The control line leads back to a cleat on the panel and the business end is attached to a high tech no-stretch line that I tie around the mast just below the deck. That allows us to easily pull the mast forward to insert or remove partners behind the mast. The magic box gives an 8:1 purchase which could just as well be achieved with a 2:2:2 cascading system of mini blocks. The problem I have not yet solved is how to jam partners in front of the mast in 20+knots. So far the only solution I have come up with is to sail with a large and powerful foredeck crew.