C.9.4(a)(2) “Mast Bury” dimension

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I believe the rules around “mast bury” could be improved.

The following language extracted from our class rules defines the so-called “mast bury” dimension.

C.9.4 MAST
(a) DIMENSIONS

(2) Distance from point B to the top of the mast step

The term “mast bury” is not used here in the actual requirement. The term “mast bury” is used as a reference in A.11.1(j). It is a fine term, it should be used as well in the actual requirement so there is no wiggle room.

Anyway, my main issue is I do not believe that “top of the mast step” is an unambiguously defined point, at least as specified in the current class rules. Mast Step is mentioned 4 times in the class rules, but I cannot find where “mast step” is clearly, and unambiguously specified.

Furthermore, there are several surfaces in the mast step area (at least on my boat), as well as a couple of unique parts, so picking the correct one that is the actual “mast step” is not clear from the language in the current rules. Maybe the “mast step” is the aluminum I-beam. Or maybe “mast bury” is measured to the top of one of the part(s) that rest on top of the I-beam. If what is actually meant is to measure to the bearing surface where the mast heel point rests, that is clearly not the “top of the mast step” if the mast step is the sliding part (on my old Ontario boat) – that part has elevated sides (to restrain the mast heel) which extend above the heel bearing surface.

So, I think there is room to improve this rule to be correct, crystal clear and unambiguous.

As an aside, the Equipment Rules of Sailing use the term “heel point” (ERS sect F.2.2) which is on the mast assembly, and probably not as useful here, since “mast bury” probably needs to be measured on the boat and without the mast in the boat. Alternatively, transferring point B to a mark on the mast extrusion is probably not trivial. But, it would be nice to use ERS terms, if they can be made applicable.

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