[MHml] Daggerboard construction

[Rob Denney]

G'day,

Well said, Rob (not just this bit--your whole post). Yes, I'd like to 
see your article.

Ta.  Article (and preliminary mistakes of a neophyte kite boater) sent
seperately.

Why do you think the high L/width ratio of masts precludes this, Rob? 
Alu masts suffer from local buckling all the time...

<Not sure, which is why I skimmed over it.  Can't find the book with the
explanation (An Introduction to Composite Materials by Derek Hull ) so none
the wiser.  Guess that once the fibers buckling issue (and all the
unexpected loads and load path issues) are resolved, the next most likely
cause is local buckling.

Keith Burgess of Maine Composites, who has one of the very few large 
presses used specifically for testing large diameter carbon mast 
sections to failure, suggests that local buckling is very real for 
carbon masts, and needs to be designed around.

<Interesting.  Does he test long or short lengths?  If it is to do with
length/wall thickness and he tests short lengths, he could be looking in
the wrong place.  Suspect not, though. Are his results published?  

>End grain balsa makes better centreboard cores than foam 

I agree with all this as well; it was why I sent the earlier post RE: 
why were the French boats using foam? 

<Answer to this is simple, it weighs less.  Suspect that they incorporate a
shear web of higher density material, and beef it up around the case base.

Regards,

Rob