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B
ack in May 1981, my son, Dave Jr.; Bob O Donnell, the
builder; and I were engaged in trial runs on
Surprise
, my
24-foot Atlantic City catboat. She was powered with a 40-hp
Volkswagen Rabbit diesel. I had installed trim tabs on
Sur-
prise
hoping she would exceed so-called natural hull speed,
which was 1.34 times the square root of the waterline,
which equals 6.284 knots. Wide open, she made 7.5 knots
while pulling an enormous wake behind her.
We pulled up to a dock to let Bob O off. As we backed away
Bob O motioned us back and he climbed aboard again.
Dave, he said, “She is running backwards real nice and prac-
tically leaving no wake.” Well, what the hell, I replied, “Lets
open her up backwards.” With me at the wheel, Bob O on
the throttle and Dave Jr. looking
at the knot meter, Bob O. slowly
applied throttle. I was well
aware of the risk involved in this
very important scientific experi-
ment. If the big barn-door rud-
der was allowed to turn ever so
slightly the extreme pressure
could have torn it right off the
stern. There was a strong
chance we would pull the prop
shaft right out of the coupling,
which would allow the prop to
bust up the rudder, and water
would come up the shaft log
and sink the boat.
Dave Jr. called out the Knot me-
ter readings as Bob O carefully
advanced the throttle 7, 7.5, 8,
8.5, 9, 9.5, 10 Knots at 4000
RPM. “
Eureka, we have a major
breakthrough in naval architec-
ture
,” I hollered!
Bob, I said,” How about if you
make a fiberglass mold of this
boat, lay up 3 models, Cut two
models in half and glass them together amidships with two
bows and no stern, and ballast both models to the exact
displacement of this boat.”
On a dark night, we towed both models of the boat at the
same time from a yoke at scale speeds from the
Surprise
in
Gardiners Basin, Atlantic City. The standard model fetched
up at a speed length ratio of 1.34 times the square root of
the waterline length as the textbooks say it should. The dou-
ble-bow model went right through the hull-speed-length-r
barrier with no hard spot in its resistance. It jumped right
ahead of the standard model and pulled the yoke all the
way aft. “Bob,” I enthusiastically exclaimed. “We just
learned how to design a boat that will win the America’s
Cup for sure. We must pull into the Flying Cloud restaura
and have a fine dinner, everything from soup to nuts, and
plan our design for winning the Americas Cup.” Bob O
agreed. We pulled the models up near the Tuna Club, tie
up at the cloud float and enjoyed dining in style,
I told Bob,” I’ve got Phil Rhodes’s book with the lines dra
ing of
Weatherly
, which won the Americas Cup. We shoul
make two models, one of
Weatherly
, and one of a new d
sign with two bows and no
stern, ballast them both to
Weatherly
’s displacement a
tow them like we just did fro
the
Surprise
and see what h
pens.”
I drew up a set of lines of for
very-high-deadrise, vee-bott
boat with pronounced hollo
waterlines aft while cutting
about the same displaceme
as
Weatherly
. On a bitter col
day after Christmas my dau
ter Marje and I towed it fro
Surprise
with the tow line at-
tached to a sensitive fish sc
to measure the resistance
above the critical speed len
ratio above 1.34. It was a 1
degree day with a 30-knot
north-west wind.
Eureka Suc
cess
! It went right through t
nominal barrier without a ha
spot.
It was my intention to make
further tests and, take my d
up to my old boss Olin Stephens to evaluate using the inf
mation for designing an Americas Cup boat. Then, it cam
to my attention that the next America’s Cup was not goin
to be decided by racing boats on the water but by a gang
confounded lawyers in a courtroom so I put the project o
the back burner.
But wait there’s more!
In 1990, my son and I were having dinner with Olin
Stephen’s at Mystic Seaport. We were both giving a talk t
Wrong Way Martin and Stephens
By Dave Martin
Dave Martin's 27-foot Atlantic City catboat,
Surprise
,
in 2007. This shows her with her 3-foot transom-
extension fishing cockpit.