Adventure, experience, education; these
were the goals driving the decision to campaign a
proa in the Watertribe EC 07. Also high on the list
was that I could have a partner that had done the
race previously, Chuck “the Duck” Leinweber,
but the window was only open for 2007. The OK to do
this madness was granted with some trepidation from
my wife Susie since I had already spent a lot of time
building and campaigning a doubles paddle boat in
the C100 earlier in the year. And she knows quite
well the time and obsession involved in building a
new boat in a short time frame.
Since Chuck and I were in the same boat
at the same time, except when one or both of us were
out pushing and pulling, I’ll let him tell the
tale of the adventure, he took notes and pictures.
(see May-June issue of "Small Craft Advisor"
magazine - chuck)
Bent
The experience was all I could have
asked for and just a little more. Wind and waves aplenty
for an old guy that usually paddles backwaters and
looks for smooth skiing water at the lake. Also, the
unspoken attitude as we traveled to Fort DeSoto was
“I’m from the Texas gulf coast and I know
all about shallow water”. A few days later I
am in Florida and learning all sorts of new things
about shoal water, tides and tidal currents. Mea culpa.
The driving force for all this effort
was to see how a proa would perform in a real and
challenging event, to find out what worked and what
didn’t. Education at a visceral level.
Waiting
A shunting proa is a sailing vessel
that has its axis of symmetry rotated ninety degrees.
Instead of symmetry around an axis from bow to stern,
symmetry is through a line from windward to leeward.
Where one puts the various components of the boat
determines whether the boat is a classic Pacific Proa
or one of the variants. P52 is pretty much a classic
pacific proa, a relatively long lean lightly loaded
hull balanced by a float to windward. Comparisons
to catamarans and trimarans are easy to make but inaccurate.
A catamaran or trimaran transfers a significant percentage
of its displacement from one hull to another to develop
large moments to support large forces in the sail
system to drive the hulls through the water. A pacific
proa on the other hand unloads just enough displacement
from the float to drive that long lean lightly loaded
hull. A delicate balance foreign to a mindset that
embraces trapezes and highly loaded everything. The
only thing fairly highly loaded on P52 is the oar
shaft that is mostly due to not having all the elements
quite in balance yet.
P52’s hull is a simple long lean
dory style hull with a fairly high prismatic coefficient
balanced by a buoyant foil, both bilaterally symmetric
(naturally) and longitudinally symmetric on the belief
that a little leeway should provide all the lift needed
and not add any extra turning moments or forces while
traveling in a straight line. And it’s a little
easier to build.
Broke
I’ve got a strong desire to keep
the rigging and time to water as simple as possible
since there’s always the comparison to a car
toppable solo double blade canoe, the gold standard
in ease of use and return on investment (time, effort
or money). So the float needed to either telescope
or fold. Folding was selected so the possibility trimming
the float back and forth a few inches to help balance
and or trim the boat could be investigated. Initial
trials were not auspicious and I now believe that
a bilaterally symmetric boat would prefer to remain
bilaterally symmetric. Overall the hydrodynamic portions
of the design seem to work well together and I don’t
see anything that cries out for significant change.
The boat handled some pretty rough water in the run
from Sannibel to Cape Romano and never buried the
bow, stern or float.
Abandonded
The sail system though, needs some significant
reworking. Over sparred and over canvassed. I was
moderately proud of the inexpensive lightweight cedar
hollow birdmouth spars. Sixteen or so pounds doesn’t
seem like very much until it’s swinging around
high on the mast because lowering it brings the CE
too far aft and everything goes completely out of
control. I suppose pride goeth before too large a
moment of inertia. This is the real visceral education
I got on this event. The rules of thumb and coefficients
for other types of boats may not be completely appropriate
for a proa. The relatively high SA/WS ratio for a
relatively crude trapezoidal/triangular shape should
have been a clue. In any event, there will be a smaller
sail cut from the current one, removing area from
the back of the sail to move the CE forward and maintain
harmony at home since Susie won’t need to restitch
the difficult edges. The mast will be abandoned and
one of the lighter yards cut down and retrimmed for
a new lighter shorter mast. The other yard may be
recut and retrimmed or there might be two new yards,
time will tell. It’s interesting that the only
hardware failure on the boat was the most expensive
piece, a spinnaker pole fitting for the yard to shuttle
shackle connection. To be fair there were some pretty
high stresses going on at the time but it is disconcerting
to have your whole sail system flapping in the (considerable)
breeze from the top of the mast and trying to tear
your boat apart [BENT]. I think I’ve come up
with a simple solution to connecting the yard to shuttle
that’s inexpensive, rugged and simple to remove.
Return
It turned out that most of the 200 miles
we made were with a 40 square foot trisail cut at
the last moment from a windbeaten plastic tarp. If
I’d popped a little curve in the carpet tape
we might have gotten there a little quicker but probably
no farther.
After we anchored at the entrance to
Indian Key Pass and watched the broken gussets at
the float connection open up an inch or more as we
bobbed in the chop [BROKE]I started to mentally break
up the boat and catalog the salvageable pieces for
its successor. But later that day watching the boat
surf along at 17-18 mph pulling hard at the bit like
a thoroughbred trying to pass the towboat I knew this
boat deserved to be rebuilt and continue the quest
[REDEMPTION - also see youtube video below].
The rebuild of P52 will have the sail/spar
changes already mentioned along with a telescoping
float system. The folding system worked well enough
when extended and also when supported on the trailer
(4500 miles worth) but was fragile in torsion while
folded. Also to be corrected is the oar support at
the cockpit, there needs to be an adjustable socket
to raise the handle of the oar to stay in deeper cleaner
water at times and to provide some more early warning
when the shallows shoal. Incorporated in the socket
will be some sort of tiller handle, there’s
too much torque required at times to just twist the
handle to steer. Also on the lower business end of
the oars, there is going to be a removable end based
on a double blade paddle ferrule to change out blades
(experiment) or put on poling ends.
Redemption
On the same oar shaft, I would like
to investigate propulsion based on what our water
cousins the dolphins and orcas evolved untold generations
ago. The hand-cranked propeller done in haste and
desperation worked well enough though I did get greedy
and lower the swing radius on the hand crank when
I should have left it alone and increased the blade
area a little bit. The issue is more philosophical
than practical. The rudder on a kayak or racing canoe
is the best way I know to describe the difference.
A flat plate rudder will work but is terribly inefficient
slowing the boat as much as turning. A well-shaped
smaller 8-12% rudder blade will be a revelation, allowing
sharper faster turns. But the blade may stall and
you are then stuck with nothing but a smaller flat
plate. However a well done scimitar shaped fin that
spins a vortex off the tip will work almost as well
as the shaped blade, and will do it every single time.
Finally if there is a successor to P52
there are a few things I know will be different and
there is surely still more to be discovered. First
the name will need to change, now that the boat is
starting to prove its self, 5.2mm underlay is probably
not the best choice for building. Then the boat wants
to be 3 full sheets long, there is plenty of time
to develop a cheap easy bi-directional masthead light
and 7 knots at night can be a little slow at times.
A little lower superstructure wouldn’t compromise
the ergonomics particularly and would cut down on
weight/windage a bit. Other changes/improvements await
a season or two of development and perhaps another
run at the EC, I can hardly wait.
