Lester wrote:. . . it may be worth noting that a number of designs would fall foul of such a rule. In these designs, the swivel attachment point is recessed in a well or channel in the deck. And, in the case of a curved or peaked foredeck, as is very common, it would be difficult for a measurer to decide whether a recessed attachment point was indeed above or below the sheer.
I am not aware of designs with a concave deck (any pointers to an image?). Sheer is a useful concept, mainly because it's defined in ERS, though I can see problems with it. I just chose it as an arbitrary, though I think reasonable, limit for the alignment shenanigans.
As I understand the definitions, the sheerline is what most folks think of as the gunwale; that sharp transition on a conventional boat between the deck and the sides of the hull; and the definitions appear to assume that this is the case, relying on "projection" where this is not a sharp cusp. I know that there are R/C boats that don't have this feature, where the transition is so gradual that it's like a monocoque structure; more aerodynamic. And now I'm told that there are concave decks. So the definition of
sheer as the projection of the
sheerline on the centreplane (I'll humour the spelling for now) would be difficult to establish for such a design. If pressed, I'd say that where the section goes vertical, that is, where a vertical straightedge placed against the hull at any station touches, that's the sheerline. String-in-hole fanatics could drop this point on their designs, but at a certain point the sublime turns ridiculous: you give up freeboard for jib attachment depth. I don't think that this would affect peaked or curved decks (such as the Cockatoo) at all.
So, having thought about it, I think that the actual addition at C.7.6 could be shortened to:
"Elements of the swivel and/or fittings, which are susceptible to changes in alignment due to rigging tension, shall not extend lower than the
sheer."
And perhaps a special definition of sheer would be necessary to deal with unorthodox designs. People with concave decks could always make up a fixing point that meets the restriction. But I think that setting a "depth" limit for the fixed attachment is the only effective way to close the loophole.
In the end, I think that stuff like this jib attachment is heading the IOM in a "development" direction, and my own opinion is that this is not in the best interest of the class. In the class's short history, we've already been through the "skiff" phase (does anyone disagree that the "skiff" is all but dead?) so all those guys need to move on to a more moderate-beamed boat to be competitive in all but a gale. Next, we'll all need to invest in a design that has these weird holes in the deck; the latest screwy go-fast that tortures the "boat-ness" of the basic design. The class should be about racing well-matched boats together, not about constantly buying and building the next best thing. So I'm all for a rule change on this one, that nips it in the bud.
