October 2009 eBook all pages (free PDF, 36.6 - Latitude 38

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"Finally!" our skipper cheered
before the echoes of the gun had faded.
"Postponement over! Let's get this race
going!"
We'd been waiting two hours for the
wind to stabilize. It had never been flat
calm, but it was not the steady sea breeze
the Race Committee wanted. Evidently
they thought it was worth the wait.
All hands on our boat felt otherwise.
They were from Southern California, in
town for a major regatta, and I'd been
recruited as a source of local knowledge.
Fortunately, I was able to bring Lee Helm
along with me. She's a naval architecture
grad student at the university, and
although I have a few more decades'
experience racing on the Bay than she
does, Lee seems to be able to make more
sense out of the instruments, the polars
and her custom tide charts. As long as
she can pass me secret tips during the
race, I can fake it pretty well.
"Wait a sec," said Lee, examining
the RC boat through binoculars. "They've
got the gun up for another shot."
The end of a postponement is signaled
by one gun, and a postponement is signaled
by two. When the second gun fired,
we couldn't understand why they would
postpone a race that was already postponed.
Then there was a third gun.
"Code flags N over A," Lee sighed. "All
races abandoned for the day."
"Darn," muttered the skipper. "I
thought we'd finally have a chance to
see what we could do against this fleet
in light air."
"Clearly a decision driven by bar
revenue," said the owner, who doesn't
drive or even trim sails during the races,
but loves to organize the campaign and
write the checks. "The bar makes more
money for the club if they get us back to
the harbor early."
"Either that or
someone on the
RC boat has opera
tickets," groused
a n o t h e r c r e w .
"You'd think, what
with having a whole
navy out here to set
marks and signal
courses, they could
at least give us a
short course in the
wind we've had all morning instead of
making us wait around for the seabreeze
that we all know will fill in as soon as
we're back at the dock."
"Down south we race in wind lighter
than this all the time," said the owner.
Page 124 • Latitude 38 • October, 2009
The formula for Sample Standard Deviation. T is
corrected time and n is the number of finishers
in the division.
"We could have spent the last two hours
racing."
"Yeah, since when is an RC so afraid
of a wind shift that they have to cancel
a whole day of sailing?" asked another
crew. "I started racing on Long Island
Sound, and back there we'd call this a
good stiff sailing breeze."
"Before you all go off half-cocked on
this," said the mainsail trimmer, trying
to calm us down, "consider that one of
the purposes of the regatta is to come
up with an overall winner. And because
they have the different divisions sailing
different courses and starting at different
times, their method of selecting the
overall winner only works if the wind is
steady."
"Well, we're sure not in it for the
overall win," the owner reminded us as
he stepped from the back of the cockpit
to the top of the companionway ladder.
"We just want to race. We came all the
way up from SoCal, and they've wasted
a perfectly good day of sailing. I'm going
below to break out lunch. Who had the
one with no mayo?"
"No tomatoes on mine," said Lee.
'"They're all no tomatoes," the owner
called back from the cabin. "Keeps the
bread from getting soggy."
"But how can they possibly have an
overall winner if the divisions are sailing
different courses?" I asked.
"It's, like, in the sailing instructions,
under scoring," said Lee. "What they do
is take the corrected time of the winner
of each division, divide by the course
distance to get the corrected speed, and
see who is sailing the fastest, averaged
over all the races sailed."
"Sounds fair enough, if the conditions
are steady."
"Except for one big thing they got
wrong," Lee noted.
"The finish is upwind
of the start,
and the big boats
u s u a l l y s a i l a
course with more
laps than the small
boats. Especially
for a series sailed
in mostly flood tide,
that makes a diff."
"How big?"
"Okay, we can
totally figure it out. "If the course is W-
L-W-L-W — or two-and-a-half sausages
— for the big class, that's three upwind
and two downwind legs." She produced a
small cell phone in a plastic bag from her
PFD pocket and switched it into calcula-
tor mode. "Let's say they go seven knots
upwind and tack through 70 degrees.
That's a VMG of 5.7 knots, subtract a
knot for flood current and VMG upwind
is 4.7. Downwind, let's be conservative
and say 8.5 knots VMG plus the current,
for 9.5 knots down the course. Average
speed for the five legs is then . . . 6.62
knots. But if they sail the shorter course,
just one-and-a-half times around, they
get a higher ratio of windward to leeward
because of the upwind finish. Then the
average speed around the course is . . .
6.3 knots.
"Pretty close, if you ask me," I ventured.
"No way! That's, like, a five percent
rating advantage. Ginormous compared
to typical finish margins in a top-end
fleet."
"What about when the course is threeand-a-half
laps versus two-and-a-half?"