Marblehead Rules

HI Dick,

Marblehead Class.

There is question to wich I have some difficulties to get a correct answer.

What is the minimum lenght of the LWL for a Marblehead Class ?

It is stated to be 1210 mm in Fig H.2 here below. (extract from Rules 2002)

Is this dimension the minimum acceptable by the rule?
Similar approach for the 30 mm from the Stern ? According to my understanding, the minimum allowed LWL should be 1210 - 30 = 1180 mm
But apparently asking around, no body care.
Any suggestion ? Thanks

I would interperate the rule to mean that the overall length of the hull can be no greater than 1290mm and no less the 1275mm.
The waterline can be of any length.

I did’nt ask for LOA where tha MIN/MAX lenghts is clearly specified without ambiguity.

" any lenght" as you said as well many others says, then why to specify the figures 1210 mm and 30mm.

Does not make sense in my opinion.

i am not sure if this makes sense but i read the rule as the over all lenght can be between 1275 to 1290. now if you take the minimum 1275. and lets say you want a shorter waterline. you are given the opition here to take 30 mm from the bow and 30 mm from the stern. this will now give you , your waterline of 1215. dont take my word for it. but the rules could read that as such. my marblehead is an old one. and i use all the waterline i could get. this is just an observation. you could cantact the marblehad rep. from the amya to get a official answer

Hi Claudio

I don’t sail the M, but I believe the diagram is a left-over from the days when the class did require waterline marks. As far as I can see, the 1210 and 30 measurements are not required by the current rules, are not measured at measurement, and are simply not relevant to the Marblehead.

On the other hand, I think there is something in the 10R class rules about the waterline marks shall not be more than 30 mm from the hull LOA…

HI Lester,
I do not intend to disturb, but I was told that I could make the LWL as short as I like it so far I can manage to put some weight in.
The H.2 Datum Waterplane is therefore an uncorrect drawing.
Thanks for the disturbance.

I have an additional question about the Marblehead rules, this one concerning sail area. I’ve asked for clarification from the class secretary, but so far have not received a reply, and I cannot find any Marblehead-specific websites.

Marblehead sail area(s) consist of the triangular area and the “excess area.” I understand the latter was added due to swing rigs that had highly curved luffs, or something like that, which is fine for historical perspective but says little about how the rule actually works. The excess area is calculated based on “excess widths” measured at the quarter points up the sail. Now here’s the tough part. The measurement form and the explanatory drawings make it clear that the excess widths are calculated by subtracting the “triangular width” and a roach allowance from the measured distance between the luff and leech. But neither offers guidance about what to do if one or more of the excess widths calculate to be negative - which will happen if the actual roach is less than the allowance. The obvious answer to any engineer is that the formula is still applied, even if the excess area then calculates to be negative. In effect, this allows a larger triangular area than the 800 sq in in the rules (which is not counter to any spirit of the rules, because one would be giving up roach area in return, the “normal” roach area not counting in the total). I’ve had an indication, though, that the intention of the rules are that negative values of the excess widths are ignored. So which is it?

Mike Biggs