Think with a Twist

In response to an avalanche of questions about how our experimental foils with the lifting surface mounted at the forward end of a ‘fuselage’ tube can be extracted from above… Here are some illustrations:


First the foil is raked top-forward so the tube sits vertically through-hull slot.
Then the foil is rotated about the long axis of the now vertical tube so the main foil strut points inboard.
Finally the lifting surface is extracted through the slot.

This concept requires that the minimum clear length of tube is equal to or greater than the local freeboard of the hull.
Obviously if a boat were designed with this in mind from the outset and a shorter longitudinal displacement of the lifting surface were required, then the local freeboard could be reduced accordingly. In fact it would only need to be stepped down inboard of the slot.

The legal lifting foil is around 450mm in span (a bit more than the 400mm max legal horizontal distance because it has a tip-up angle). So the slot can be at a minimum around 380mm long. The width of the slot is equal to the diametre of the tube which on our prototype is 35mm.

More testing is needed, but initial indications are that stability is good, performance at foiling speeds is promising but the drag penalty at low speeds is significant.


Finally, and also in the spirit of sharing our development journey, an answer about the way we intend to extract from above an L/V foil with an acute included angle:
The smallest possible cassette would be one with a length equal to the span of the horizontal foil and a width equal to the chord of the foil. The foil would be rotated 90 degrees about a vertical axis once the cassette is raised.

The search continues, but so far the Class has seen only solutions that are either inventive but unnecessarily complex (cassettes, hinged foils, leeboards etc.) or limited in terms of performance (J and ‘comma’ or ‘chevron’ foils).

The latter are perceived by many to be an acceptable compromise and have in some cases turned opinion back toward keeping the Rule unchanged.
However the unexplored potential of ‘true’ foiling (as opposed to sometimes foiling on compromised appendages) remains vast. Exploring it is fascinating. Doing so within a now anachronistic rule makes it more challenging. But challenging quests can have surprisingly positive outcomes. So let us press on…

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