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From: Colin Smith (Colin.Smith@msdw.com)
Date: Wed 29 Dec 1999 - 14:22:43 GMT
Having measured my Bieker II in the garage over the weekend, I reckon it's
about 52cm from bottom of daggerboard case to top of existing sheerline band
(but it's very hard to measure, depending on how you bridge the gap from the
front of the case to the mast area). If so, and as my rig is the max 7626mm
above the band, the result of this proposal is that I'd have to lose 12mm
from the mast - which means either shortening and hence losing all existing
calibration for the uppers, main shrouds, lowers, forestay, kicker, etc, or
reducing the A measurement and finding some way of moving the spinny halyard
down. Either way, much hassle to achieve what? - well, not a lot really.
Seems if the implication of the measurement proposed in this rule is that
half the fleet (ie anyone with a hull which is not on the absolute minimum
sheer height) have to start cutting bits (even if only small bits) off
their mast, it isn't really what we want - it was supposed to be just a
tidy-up to make measurement easier.
Turning to why we have a max rig height anyway, can we get away from all
this, since basically we don't have a convenient horizontal reference point
from which to measure it? Presumably the limit is to stop (at least
unless/until we positively decide we want it) development of tall thin (is
'high aspect ratio' the technical term for this?) rigs and/or enormous
spinnakers. Could you do this just by limiting the mainsail "A" measurement,
and by saying that the spinnaker halyard can't be any higher than the top of
the (unreefed) main (so you couldn't have an extra 3 feet of mast just to
carry a big kite)? "A" has to be measured anyway - no additional
measurements would be needed.
I suppose someone could stick their boom way up in the air with a normal
main above that, if they wanted to get an enormous kite (in a bit the same
way they can now build a boat with a very high sheerline), but the
weight/righting moment disadvantage should be self-limiting, shouldn't it?
Cheers
Colin Smith
I've been wrong before...
<p><p><p>Grant Bourke wrote:
> Peter Rundle wrote:
>
> >
> > So how to come up with a number that didn't suddenly force half
> > the fleet to take to their masts with a hacksaw. So I picked the
> > old max aussy hull depth, added a little bit for good measure and
> > came up with 700mm + 7600 = 8300mm being a nice round number. It
> > was felt that any hulls deeper than 700mm were getting quite an
> > unfair advantage and so should be pegged back. So 8300 was the
> > original measurement proposed which was still slightly lower than
> > the maximum height rig you could carry under the old Australian
> > rules (7900 above sheer if I remember).
> >
> > I don't know what made "the powers that be" cut the 8300 down but
> > perhaps this may help them re-think the number.
> >
>
> Well as one of the very few who won't have to cut down his mast cause my
> sheerline is only just over 508mm I was actually looking forward to
> going up a couple of inches because getting the area in without having
> too long a foot on the main or too much roach is a tad difficult. I
> think the original idea of the aussi maximum sheer height plus the new
> rule mast height from sheer made sense. I don't know about "adding a
> bit" though.
>
> The problem I had was the practicality of measuring. The deepest part of
> most boats when you look at the drawings for them is about station 3
> from the bow or 1150 or so from the bow whereas the centrecases are way
> further aft. The other thing about measuring down the centrecase is that
> rake comes into it a little bit. This is nice and simple though. However
> if we want to measure down the centrecase then that should be stated in
> the rule, not "the lowest point of the hull"
>
> Alternatively we could have another band at some nominal point say 1m
> above the lowest point of the boat and then have a rig height from here.
> This band would not necessarily be remeasured at each regatta. This way
> the mast rake setup would not matter.
>
> Cheers
>
> Grant
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