New Fun with an Older boat
Optimizations, Alterations & Upgrades
Choppy financial waters continue to buffet the world economy in general, and the sailing world in particular. Despite a substantial recovery in many their portfolios, many sailors remain cautious about spending the amount required to build the nice new boat they have been dreaming about. Still, the sailing bug has no known cure, and those who suffer from it are resourceful in finding other ways to indulge their favorite habit. One popular approach is to upgrade the boat that they already own. While some designers disdain being ‘Mr. Fix-It’, I enjoy and embrace the performance optimization/alteration work that has come my way. Its’ ‘before and after’ aspects often provide not only a chance to do what amounts to full-size analytical testing, (which we incorrigible gearheads don’t get to do as often as we would like), but also a nice opportunity to make some good boats even better. These projects have gained me a lot of new sailing friends, some valued clients, and an even broader, deeper understanding of the incredibly complex physics of sailing.
The first of these projects that I can remember was done at the behest of a then 20-something Jud Smith, who wanted a new spade rudder to replace the original skeg rudder combination on his family’s Tartan 41. I had recently left Ted Hood’s ‘grad school of sailing technology’ to go out on my own, and while I knew that I could design a good rudder, it was Jud who was more sure that the change would result in a big performance improvement. The last race of the ‘before modification’ season was in an offshore northwester, resulting in nice smooth water testing conditions. In the puffs, as the heel and weather helm would increase, the driver would have to add about 10 degrees of rudder angle to compensate, and the boatspeed would actually go down. It happened that the first ‘after’ race of the following spring was in nearly identical conditions. With the spade rudder, the heel and weather helm increased in the puffs in just the same way, but now the driver could compensate with only 2-3 more degrees of rudder angle, and the boat accelerated very nicely. The Smith family was encouraged, and the rookie designer was impressed, but an even better measure of ‘Drummer Boy’s transformation came a few weeks later in higher end competition in Newport. We came off the starting line in our aging, plain vanilla production boat (with the tree-trunk single spreader rig and the full cruising interior) just to leeward and even with a brand new, high tech, fractionally rigged custom race boat whose crew was no doubt expecting to roll over us without even trying. After a few minutes, we were still right there, and we could see some control lines being tweaked. After a few more minutes, we were still gaining, and they were peeking anxiously under the boom: “Who are those guys?!” Soon enough they were forced to tack away, unnerved, and despite owing us a lot of time on handicap, they never did get by us. The advantages of the spade rudder were obvious and inescapable, and I have done a number of similar surgeries on a number of similar skeg/rudder afterbodies since. Two Swan 44’s (who went on a mid-90’s racing rampage), two Seguin 44’s. and a second Tartan 41, (Fig 1) among others, have all had similarly happy results: better straightline speed, far better maneuverability, no loss of ultimate control, and most importantly, lots more fun.
A lot of otherwise perfectly good boats are compromised by a non-optimal feature among the many that can characterize the boat. One of the most common is inadequate sailing stability, when the righting moment generated by the hull and keel is too low relative to the heeling moment generated by the sails. One case in point is the shoal draft version of a generally attractive, well conceived and well built racer/cruiser that badly needed the weight of a full racing crew on her rail to sail effectively in breeze upwind. Her owners found her cranky, hard to control, and hard to enjoy when cruising shorthanded. The righting moment vs. heeling moment data was readily available, (her stability had been measured for racing), and it was obviously and substantially ‘below the curve’. (See Fig 2, Stability data plot) The solution was a new, slightly deeper, and heavier keel that increased her righting moment by nearly 8%. The new keel (See Fig 3, keel rendering) featured a sophisticated flare at the tip and larger profile area. A new, larger rudder also contributed to the performance improvements, but by far the most important component was the increase in stability. With the new appendages she has won more than her share of races, including her class in the Bermuda Race, and now her owners are excited to be able to enjoy her fully when cruising as well.
Another example of a boat that benefited from more stability was a 45-footer of my own design. In my defense, the handicap rule of the day overweighted stability, so designers exploited this apparent loophole by keeping stability artificially low. In hindsight, I think that for many owners that small rating advantage was likely a net loss in real world performance vs. rating, because the lower stability made those boats much harder to sail consistently well. In any case, that rule was dropped in favor of IRC, which (for better or worse) does not measure stability at all. Since stability is a primary determinant of performance, bringing my 45-footer’s stability up into the optimal range via a new, heavier keel with a lower center of gravity was a no-brainer, and the boat has been a very consistent winner (and been much easier to sail) ever since. Incidentally, note that Goldilocks would have been good at optimizing stability: Too little, and her boat would be difficult to handle and lack power in breeze. Too much, and she would sit bolt upright in light air, and be unable to either drape adequate shape into the sails or generate enough feel in the helm. Somewhere in between (Again, see Fig 2) is ‘just right’.
Bill Koch was shy about indulging his sailing habit, and I (and my clientele) have been prime beneficiaries of his profound intellectual curiosity about the science and technology underlying the sport. I have learned an enormous amount in contributing to his 1992 America’s Cup win, his Women’s Team near miss, and most recently, his 12m World Championship. I learned three critical lessons from his team’s ‘tune up a 1987 12m’ effort. The first (and perhaps most important) thing learned (re-learned?) was humility; a lot of smart guys have been optimizing to the 12m rule for over 100 years, and we found that there are some blind alleys to go down, and there are not any easy home runs left to hit. The second was a re-affirmation of the immutable fact that there is no substitute for focused full-sized testing. The third was a whole boatload of knowledge about the subtle and complex relationships between lift, drag, and shape details in keel design. Specifically, I have gained new insights into the optimal volume distribution of keel shapes and the fluid flow patterns around them, and have been able to apply them to continuing refinements of keel shapes that I have been using and developing for decades. Recent applications have been new keels for 52 ft and 48 ft semi-custom cruisers, a 42 ft production cruiser racer, a 38 ft daysailer, and the new Sabre 456, all with very satisfactory results and very happy owners.
One of the most interesting and challenging of these performance optimization/alteration opportunities also involved the oldest boat. Bob Miller and MaryAnn McElroy have owned and loved their full-keeled Mason 44 for over two decades. They fully intend to sail Mast Transit for at least two decades more, but sensed that they might love her more if they enjoyed being under sail more, (and had to resort to being under power less). They also did not love the fact that when the breeze was up the helm loads were high and steering was a chore. They asked me for a laundry list of possible upgrades, so they might choose those that seemed feasible and cost effective. My list started with the familiar bugaboo of low stability, and since the full keel was molded integrally with the hull and not detachable, this suggested an ‘add-on’ keel bulb attached to the tip, which would have to be fabricated partly in high density plastic, partly in lead. A rudder profile change also made the early list, since I thought that the tip vortex trailing the keel was catching a big section of rudder area down low and pushing the helm loads up. A ‘boat call’ to Greenport, Long Island was scheduled to meet the boat and her owners, and to accompany Andrew Williams as he laser-imaged the hull and keel to facilitate the keel bulb design details. Inevitably, this on site inspection greatly expanded the possible ‘to do’ list. The forward third of the keel, and especially its leading edge, clearly needed reworking into an effective foil shape. The rudder also had a massively thick trailing edge, (Al Mason’s gorgeous original design drawings were originally intended for wood construction), which also contributed to the high helm loads. Mike Acebo, of Brewer’s Greenport, listened patiently to all of the challenges that I proposed to throw at him, he assured us that “nothing that I described (Fig 4) had scared him yet”, and he agreed to estimate project costs. In addition, the rig and sail inventory were both tired, so the owners entertained the idea that the time might be right for a new, taller, rig; the lighter weight of a modern carbon fiber tube would increase stability enough to carry the extra sail area. In the end, Bob and MaryAnn took a deep breath and selected ‘all of the above’ from the laundry list. The Brewers Greenport crew reshaped the keel and built a new rudder; Henry Maxwell sheparded the new spar through the high-tech HallSpars facility in Bristol, and Quantum supplied new sails. The boat was re-launched in mid-summer with the modified underbody but without the new rig, partly to suit logistics, and partly to test the effects of the underbody and rig changes separately. Even with the original rig and sails, the boat was now dramatically faster, especially upwind, and the helm was considerably lighter. In the racing world, an improvement in performance of 6 sec/mi VMG is a big deal; Mast Transit was going faster by at least 60 sec/mi, sailing both higher and faster. Many smiles… The icing on the cake came in September, with the new rig and sails. Phil Garland (HallSpars) and David Flynn (Quantum) were on hand for a rig tune and sail check in a strong and puffy northwester. The extra sail area wasn’t an advantage in these conditions, but the new sail shapes (and lighter rig) were. The boat handled the conditions well, under control and charging along with a two-finger helm. All the reports from later in the fall were equally positive. The straightline speeds have increased by at least a minute/mile, helming is now a two-finger pleasure, and the diesel has been in gear far less often. Bob and MaryAnn are very much looking forward to their next few decades with Mast Transit.