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From: skimmer <skimmer_at_enter.net>
subject: [Paddlewise] sailing canoe troubles etc
Date: Mon, 12 Jul 2010 15:14:57 -0400
Many thanks to Craig and Joq for their generous accounts of their medical
challenges.

 

In the long past years, I used to run to stay in shape for paddling.
Paddling was never much of a respiratory challenge back then. I used to run
10 k races. My best time was 7 minutes a mile (twice only). Thought I would
never do more than 8 minutes a mile. Can't run anymore-my knees can't take
it. I am reduced to walking and am happy with 8 minutes per half mile.

 

Now it's paddling to stay in shape. Best time is 60 minutes for 5 miles with
my old Mariner Sprite. When I got that boat (my wife got it for me), Matt
told her that I was too big for the boat (6'3", 210lbs). Ever since then I
have been trying to figure out what's wrong with the boat so that I can get
something newer that will help me go FASTER, so that I can be farther ahead
with my 9 ft paddle, but can't find the problem so still keeping the boat.
Used it last week in small craft warning winds on the St Lawrence River-
straight up wind of course for a couple of miles. You would have thought the
wind would take my 9 ft paddle and blow me back down to the International
Bridge. 

 

One summer day out racing our sailing canoes (standard 16 ft canoes rigged
with sails) I had on a new pfd with plastic snap buckles. While leaning hard
on the rail with my chest while racing up wind, I heard something crack with
a loud pop. I was busy staying upright at the time-we don't use outriggers.
I thought to myself something about the obviously cheap-hst pfd I had
purchased-busted buckle first time I used it. I have continued to use that
pfd for many years since then. Nothing at all wrong with it. After some
weeks, my cracked rib quit hurting as well. I don't lean my chest into the
rail to keep the boat up any more, however.

 

Here is a question for Joq. We once participated in a demonstration
helicopter rescue of a paddler in distress in the water. We had half a dozen
of us in a group with one swimmer to be picked up in a basket lowered from
the standard red and white rescue Huey. One of our fellows took the
"victim's"  boat. The victim fired off a little red smoke canister-looked
like a tiny little pink fart that instantly was gone in the breeze. The
rescue chopper whooshed in and lowered the basket and the victim climbed in.
The rest of us stood off about 50 yards. We could see the down draft race
toward us as a wall of spray. We each had to get our heads down on the decks
of our boats. The spray felt like sand pellets. My 9 ft paddle kept me
firmly upright. I was not blown off across the bay. Clearly I am just not
understanding how this paddle is supposed to be used to cause endless
disaster. I should have had one of this little short busted paddles created
in storms.

 

My question for Joq:  What is the likely wind speed created by the downdraft
of the rescue helicopters? That breeze was a hell of a lot stronger than the
35 mph + breeze I paddled in on Long Island Sound one September afternoon in
the tail end of an east coast hurricane. That day there were some cops in a
squad car watching me from the beach at Orchard Park. I could not hear
anything they had to say and there was no way they could reach me, so I just
ignored them. My white water paddle (6.5 ft Iliad) had to be in the water
pulling at all times (Cascade river kayak). I made about 1 ft on each
stroke. I lost about 3 ft if I paused for any brief moment. It was a strong
breeze. The Coast Guard was out pulling some big sail boats off the rocks.

 

I certainly hope that Craig will keep us informed on his progress with his
new knee!

 

Chuck Sutherland
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From: Martin, Jack <martin.jack_at_solute.us>
subject: RE: [Paddlewise] sailing canoe troubles etc
Date: Tue, 13 Jul 2010 02:09:12 +0000
Dr. Sutherland asked me a technical question: those very few who happen to
know both of us will see great humor in that, since I am in no way a technical
expert on much of anything.  That said, I'll come up with an impressive and
potentially accurate response.  Or not so much.

Chuck says:

"Here is a question for Joq. We once participated in a demonstration
helicopter rescue of a paddler in distress in the water. We had half a dozen
of us in a group with one swimmer to be picked up in a basket lowered from the
standard red and white rescue Huey. One of our fellows took the "victim's"
boat. The victim fired off a little red smoke canister-looked like a tiny
little pink fart that instantly was gone in the breeze. The rescue chopper
whooshed in and lowered the basket and the victim climbed in. The rest of us
stood off about 50 yards. We could see the down draft race toward us as a wall
of spray. We each had to get our heads down on the decks of our boats. The
spray felt like sand pellets. My 9 ft paddle kept me firmly upright. I was not
blown off across the bay. Clearly I am just not understanding how this paddle
is supposed to be used to cause endless disaster. I should have had one of
this little short busted paddles created in storms."

"My question for Joq:  What is the likely wind speed created by the downdraft
of the rescue helicopters? That breeze was a hell of a lot stronger than the
35 mph + breeze I paddled in on Long Island Sound one September afternoon in
the tail end of an east coast hurricane."

Joq's response

I'd much rather discuss the pink fart generated by the smoke canister -- it
had to have been expired or soaked or or a dud or something, because those
things put out great clouds of orange -- sometimes looks a little pink --
smoke.  Much more of a major flatulencial event than that described.  But
that's not what is being asked, unfortunately.  (Where is Dr. Peregrine
Inverbon when he is really needed; his explanation of so many pithy questions
by virtue of human intake of Caribou paunch would add significant clarity to
this issue and dispell pink clouds summarily.)

Okay, rotor wash velocities.  Gonna depend.  Gonna depend on the size and
weight of the helo being used, the density of the air and possibly the phase
of the moon.  Or not.  But lets use a medium sized commercial helicopter that
I know a little bit about -- the Sikorsky S-76.  (It was going to be the S-74,
but stuff happens, and it became the S-76, which was very patriotic -- while
also the year of its introduction.  Kinda.  (Of absolutely no value is the
fact that the S-76 was the first helicopter ever designed for commercial --
not military -- applications; first flight in 1977 -- which we thought was
pretty close to 1976, so we didn't rename it again.  People forget this stuff,
anyway.)

The S-76 has a rotor diameter of 44', and at a mission weight of about 11,000
pounds -- heavy but not untypical -- a rotor loading of about 7.5 pounds per
square foot of rotor disk is generated.  Trust me on this -- my math notes
don't appear in the margins.  (Contrary to popular belief, a rotor system is
not pushing the air below it down: it's using its rotating wings to pull the
helicopter up through the airmass -- although it still generates some pretty
awesome downdrafts as a side effect.  Maybe a distraction -- sorry.)
Initially, the helo downdraft is about 25 knots, but for reasons of physics
and stuff, it accelerates as it descends.  Typically, the speed of the
downwash doubles as it gets to the water surface when the helo is about as
high as its rotor diameter -- with a nominal 40 foot hover.  So, at the water
surface below the helicopter,  you may have an air velocity of about 50 knots
at the edge of the rotor footprint.  The air spreads out near the surface at
about the height of a kayaker's head, unfortunately, and at 75  feet from the
helo footprint, the airspeed disipates to about 20 knots.  At Dr. Sutherland's
150 foot standoff, the downdraft would have been considerably less than 20
knots.  But the real effect of downwash isn't the moving air: it's the stuff
in the air -- sand, pebbles, etc -- or droplets of water in Dr. Sutherland's
case that causes the problem, and makes people dive for cover.

So, sorry Chuck.  Your Long Island Sound hurricane's 35 knots trumps any
typical rescue helicopter's downwash at the standoff you report.  It was the
water droplets and stuff in the air that created the helo/human difficulty,
not the speed of the air itself.  And from my brief experience in paddling
Long Island Sound waters -- where I grew up -- I hope your exercise was held
at a different body of water.  I wouldn't want droplets of Long Island Sound
water hitting me in the face!  It took two weeks to get the grime ring off the
Pintail the last time I paddled the Sound -- and it wound up taking Brillo to
get it clean!

How's that for an English major's analysis of rotorwash?

Joq
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From: Craig Jungers <crjungers_at_gmail.com>
subject: Re: [Paddlewise] sailing canoe troubles etc
Date: Mon, 12 Jul 2010 20:45:37 -0700
On Mon, Jul 12, 2010 at 7:09 PM, Martin, Jack <martin.jack_at_solute.us> wrote:

> I'd much rather discuss the pink fart generated by the smoke canister
>

This practically begs for a digression..... so I'll add one. :)

Some years back,  I was working on a drill rig in the Davis Straits almost
within sight of Greenland (we flew in and out of Sonderstrom Fjord). I say
"almost within sight" because we regularly had the most intensive mirages
that would let us see mountains on Greenland that were well below the
horizon. But I digress...

Greenland offers the most spectacular helicopter flights I've ever taken;
and I've taken a bunch. We would rotate on and off the rig in Greenlandsfly
helicopters that would occasionally take the scenic route back to the old
former Air Force base at Sonderstrom Fjord. Several things remain in my
memory but the most poignant and most entertaining is that of young
Greenland children lining up around the helo pad in their small community
and as the chopper's downdraft got larger and larger they'd invert their
parkas and hold them cupped above their heads and lean in towards the
aircraft.

The downdraft would lift the kids and push them back until they were too far
out to stay in the air and they'd touch down. Then they'd run forward to do
it again as often as they could before the chopper either got too high (if
taking off) or shut down (if landing).

These Inuit children who lived - in many ways - a primitive existence had
invented a game requiring one of the most sophisticated pieces of machinery
available to mankind. A game only offered to children served regularly by
helicopters in a culture that allows them to take risks and have fun.

I always wanted to be one of those kids instead of a guy inside the chopper
watching them.


Craig Jungers
Moses Lake, WA
www.nwkayaking.net
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