Heavy Lifting - Sail Magazine

Heavy Lifting

We all want our boats to be more stable, but how can this be accomplished? The conventional solution is to hang more ballast off a deeper keel. Think more progressively, and you’re talking about water ballasting, which, while effective, also adds extra weight. Go sci-fi, and you’re canting your keel to windward—which is very effective, but is complicated, accident-prone, and still depends on
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We all want our boats to be more stable, but how can this be accomplished? The conventional solution is to hang more ballast off a deeper keel. Think more progressively, and you’re talking about water ballasting, which, while effective, also adds extra weight. Go sci-fi, and you’re canting your keel to windward—which is very effective, but is complicated, accident-prone, and still depends on weight. Plus, you need extra underwater foils if you want to sail a straight course.

The Dynamic Stability System (DSS) is such a simple concept it’s amazing it has not been tried before. The system, which has been patented by UK-based yacht designer Hugh Welbourn and has undergone five years of R&D, uses a simple retractable horizontal “wing” foil (located on the boat’s maximum-beam section just above the waterline) to create lift when deployed to leeward when the boat accelerates. In theory, the faster the boat sails, the more lift the DSS generates. The DSS Web site (www.dynamicstabilitysystems.com) claims that the system offers greater speed, simplicity, comfort, and safety than other stability-enhancing solutions, while simultaneously requiring less draft and displacement. According to Welbourn, all that’s required is a ballast keel that provides a baseline of stability (a minimum angle of vanishing stability); all other stability will come from the DSS.

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The system is IRC-legal, can be retrofitted to both cruisers and racers with a minimal loss of interior volume, and also works to reduce rolling and pitching. It could also reduce costs—less lead is needed in a boat’s ballast keel, plus for larger boats the DSS is simpler to build and maintain than a canting-keel or water-ballast system. Welbourn claims that, unlike other stability-enhancing systems, the DSS is fail-safe; if it should stop working, the boat—which is already self-righting—simply reverts to “normal” mode.

The DSS has been tank-tested and is currently installed on a remote-controlled boat, a Brisbane-based Boatspeed 23, a 27-foot sportboat, and a 40-foot offshore racer. An existing 94-foot Wally is considering a retrofit, and a new 150-footer under construction will likely also use the system. While some questions remain—for instance, how much drag the foil creates—the thinking is certainly progressive and could prove to be the next biggest thing in sailing since the advent of laminated sails, if it works.

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