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Long-Term One-Design, IOD-Style

posted May 22, 2017, 7:09 AM by IOD-WCA Webmaster   [ updated Jun 8, 2017, 7:04 AM ]

This article is a work in progress. It highlights some of the changes in the class over the years that have kept the class competitive, fun, and relevant. Many readers will have knowledge of another part of this story. Please submit comments to the Class Secretary for correcting or adding to this piece. It will remain on the class website as part of class history.


From early in the 20th century, there were many fleets of keelboats created as onedesign classes, but the International One-Design Class is extraordinary among boats 30-feet and longer. Many of these classes continue today, but few have been successful in avoiding the obsolescence of the early boats, with fiberglass hulls, aluminum or carbon rigs, and the modernization of hardware and cordage. The work of a number of dedicated individuals and the strength of many individual competitive fleets had a lot to do with the success that the class has achieved in 80 years.


One-design concept – When Corny Shields formed the class, he framed the rules to keep costs from driving down class growth. He developed a sail purchase plan to buy new sails for every boat in a fleet at the same time. This leads to a 5-6 year life for mains and 3-4 years for jibs or spinnakers. He limited costly mid-season haul outs as a drier, lighter boat might have an edge. It was a time of few rules. The boats were all the same from the builder, and there was no need to specify sail dimension or rig position in a set of rules. The top sailors in the region came to sail against Corny. With few rules, they experimented to find the best way to balance and make their hull go through the water a little faster than the identical hull alongside. Finding the best setting for the head stay length or the jumpers, the rake, or tension or position of shroud attachment was the game to get the best power out of identical boats and sails. Corny gathered many great sailors, and the fleet grew as the thrill of competing against the best attracted many who wanted to learn from the masters.


Transition to glassThere were similar developments at the other early International Class (as it was then called) fleet venues in Bermuda and Northeast Harbor. But these fleets in vastly different climates and different length sailing seasons had different wear and tear on their boats. As aging of all the fleets moved on there was a demand for new boats from new materials. Early fiberglass boats, stronger and lighter in many other one-design classes, had obsolesced the older wooden boats. Jim Bishop knew from personal experience in the Atlantic class that it was tricky to bring in glass boats while keeping the wooden boats competitive. Working with top naval architects, he helped the class design a fiberglass layup schedule for the new plastic IODs that gave the hulls the same weight and weight distribution as the original wood boats. Initially built by Bjarne Äas, the builder of the wooden boats, the successful outcome showed no speed differences between the two construction techniques. The class soon built two sets of molds and licensed other builders to use them. By the 1970s and 80s, nearly all of the 1937 wood boats in Bermuda were replaced by glass boats, some from Europe or the US, most from the Bermuda IOD Company. Of course, there were some minor differences, but the boats were designed with 75 mm of fore and aft latitude in positioning the mast at the step and the partners. This skipper’s choice in setting up the rig permitted good sailors to find the right power and balance settings for each slightly different hull and sails.


Aluminum rigs – These initial mast position decisions in different boats were with wooden spars, but mast technology was also advancing with new materials. As different fleets sought aluminum mast solutions, the class management was very hands-off, leaving fleets to make their own decisions. Marblehead sailors did independent wind tunnel testing on different mast sections at MIT to determine that the Kenyon section for the J-30 spar had windage characteristics closest to the wooden spar section. The lads in Corny’s fleet worried that the Etchells 22s starting 5 minutes behind them would often finish ahead of the IODs, so they selected a smaller aluminum section with less windage, raised the hounds, removed the upper spreaders, and lengthened the spinnaker pole in order to amp up the IOD in their light Western Long Island Sound breezes. Bermuda sails with a similar rig. San Francisco had different manufacturer choices and selected a Ballard spar with the Classic Rig, double spreaders and jumpers. Northeast Harbor, with a short season, cold winters and great local craftsmen continue to use wooden spars, some of them original from 1938. In Europe, they needed yet another aluminum spar maker, Selden who mimicked the Larchmont configuration, or the Modern Rig in the present Class Rules. In 1996, Norway held the World Championship in about 20 host provided boats with half wooden Classic Rig and half aluminum Modern Rig. The competitors changed boats every race and saw some slight advantage of one rig over the other in the range of breeze seen that week, but boat swaps made it a fair competition. This validates the class rules that permit the owner to set up his own rig with few dimensional restrictions.


Hardware and Cordage – Over 80 years, some hardware naturally wore out. Different builders had to replace some hardware with what they had locally. Meanwhile the Harken brothers brought us a whole new panoply of hardware choices. With the minor differences on hulls and rigs largely dialed out by owner rig setup, the differences between substantially equal boats often came down to boat handling. This has become another puzzle for owners to figure out how to help their crew come out of maneuvers in the fast lane. Travelers had not been invented when the boat and rig was designed in 1936, but they helped depower the big IOD main in a puff without opening the leach and without breaking a wooden boom with vang sheeting. Two-to-one original jib sheets with Vernier fine tune gave way to one-toone to a winch that was lighter and vastly superior to the winches of the 1930s. Head knockers, barney posts, Cunninghams, twings and through the deck blocks to racks of cam cleats have all appeared on many IODs. Kevin Mahaney, Olympian and Maine IOD sailor developed a more modern application of Harken hardware for sheeting and other adjustments. Since then, stripped double braid did away with carrying both heavy and light spinnaker sheets, and four-to-one fine tune tackle on Spectra main halyards eliminate many a halyard winch. These differences between individual one-design boats give some crews an advantage in honing their boat handling skills in their regular fleet racing. Differences in running rigging also challenge the teams at borrowed-boat championships when the crews change boats after every race and must quickly train themselves with many new and different sail controls. It seems that every one-design class started prior to the Laser has dealt with many of these changes. For the IOD it is a way to keep our 30- and 50- and 80- year-old boats competitive against the much newer boats.


Rules for Class Growth – As mentioned above, when Corny Shields started, the rules were essentially to prohibit high cost boat speed alternatives. When the class constitution and championship regulations were penned sometime in the 1960s or 70s, there was a reliance on the authorized builders turning out long lasting boats with the same hull and sail plan as boats built before. There were a few specified dimensions such as on replacement deck thickness to prohibit the use of significantly lighter materials. It has taken a great measurement effort by Charlie Van Voorhis and the Technical Committee to produce the Class Rules in 2015, recently updated with the help of World Sailing. Now they specify that the hull as designed, built for equal original weight and distribution, and a sail plan that can be held aloft by either the Classic Rig or the Modern Rig, and each fleet is to designate one rig or the other. Fleets can specify other local rules such as what electronic instruments can be aboard, but the class rules that define an IOD are open. If the class rules do not prohibit something, then it is allowed, and owners are only limited by class dimensional rules. The choice of rule structure is required by World Sailing to be closed or open and any choice but open rules for an 80-year-old class with boats, rigs and sails made by more than a dozen different manufacturers would be chaotic. Each owner has wide range to configure his boat to suit his purposes and ideas, and fleets or sailing instructions may not establish more stringent rules than the Class Rules without consent of the Class for a local exception. Having the openness to attract each owner’s ingenuity is a strength that has served the class well over four score years of technological development and it’s application drives keen competition.


June 2017