Them I'm sorry to inform you that the SC/ARC mast is not the most streamlined aluminium mast for a doublehander nor singlehander.

Summary: The SC/ARC mast : has a design point chord of 6.5 ins and a max width of 3.25 ins for a slenderness ratio of 2.0 was designed in 1978 and is of the NACA 0050 type.


The mast section (which shall remain nameless) I hold in my hand right now (a cut off from a full length section that was to long) was designed in the mid 80's.

It's minor axis max length (= max width) = 63 mm = 63 / 25.2 = 2.5 inch
It's major axis length (including the sailtrack which is part of the fairing) = 151 mm = 151 / 25.2 = 5.99 inch = say 6 inch

Its slenderness ratio (as you defined it) = length / width = 151 / 63 = 2.397 = 2.4

Of course its frontal projected area is only = 2.5 / 3.5 = 71 %

I have difficulty in decyphering your elliptic tip measure. "It has a design point chord of 6.5 ins". I'm far more familiar with defining tips like these by the radius of the approximating (smaller) circle. The mast section I hold has a approximation tip circle of radius 22 mm = 22 / 25.2 = 0.87 inch = about 7/8 inch. The mastsection wall leaves the approximating circle at 16 mm height = 16/25.2 = 63.45 % = 63 %. I also think that the design cord alone doesn't fix the round; it needs a second parameter. But I concede that I may have misintepreted the measure.

I don't know its base NACA foil section.

Nevertheless : with a higher slenderness ratio and reduced frontal area, the mastsection I hold in my hand is the better of your named section when looking at streamlinedness. I really don't think the elliptical tip round will differ much between the sections especially not since your mast is wider for a given length which forces the tip round to be less elliptical.



>>>When compared to Hobie, Prindle, Nacra and Tornado masts of the same period, the SC section was the only one with a thickness to chord ratio as low as 0.50. It had a slenderness ratio of 2.0, better than any of the other boats of its time

Ahhh, but this is not what you've said in your other post.

You clearly stated (and I quote) :"The SC/ARC mast section is the most streanlined section, Al extrusion, of any sections available for two person boats."

I hold a doublehander alu mast extrusion in my hand that is counterproof of your statement.

Fast and Safe Sailing as well Bill,

Wouter