Wind. Wind. Wind.
July 24, 2010
This day was shaping up to be a great day for sailing around the
Point. Currents on the rivers were low. There was a mere 10,000 cubic
feet per second flowing on the Ohio. That is a current that I'd come
to know well as causing little if any trouble. By late morning, the
forecast (click) was
calling for West South West winds through the afternoon that would
rise from 11 to 13 mph. That was plenty of wind. Indeed I hoped that
would all the wind I'd see. Any more would just make trouble. That
thought proved prescient.
When I wheeled my bike out onto Liberty Avenue downtown and met a
blast of hot humid air, I had no doubt that the temperatures forecast
in the high 80s had come. Crossing the Allegheny River at the Sixth
Street Bridge, I could see the WSW winds blowing straight up the
Allegheny River. That direction was confirmed by the flags on PNC
Park, visible from the bridge. That was encouraging. Sometimes the
buildings on either side can block the wind on this stretch of the
Allegheny.
I paused at a few spots along the river to gauge the wind as I
cycled farther. Winds were gusting roughly from 6 to12 mph and
blowing from the South West. That fitted the forecast, but was more
wind than I expected to measure. At the river itself, you expect to
measure winds at a little less than the forecast speeds.
By the time I arrived at the Newport marina and rigged my little
boat, a new plan was forming. The winds were blowing steadily and
strongly from the West, roughly, along the Ohio River. I had, until
now, always sailed upstream, so that whatever happens, the current
will always carry me home. With winds as steady as these blowing
upstream, perhaps this was the day to try sailing downstream to visit
Brunot Island. I'd need to tack into the wind to get there. But my
ticket home was an easy sail running ahead of these winds.
It was an attractive plan. Downstream has an interesting
collection of islands, Brunot being the first. In my runs along the
river trails, I'd wondered how I'd fare trying to negotiate them.
Alas, it was not to be. I'd forgotten that these winds had a
Southerly component, so they were somehow making their way around the
high hills on the Sourthern shore. That made them unreliable. (Read more) I pulled out into
the river and started to tack into the winds. At that instant, the
winds died, as if responding to a hidden cue. The GPS plot shows the
story:
I set out from the Northern shore, intending to sail up towards
Brunot Island, whose tip is just visible, I got halfway across the
river when the wind died. I meandered about in a spot nearer the
Southern shore, with too little wind to carry me anywhere. A large
riverboat from the Gateway Clipper fleet had just sailed past this
very spot and would be back shortly. I needed reliable wind to keep
out of its way. This was not the day, I realized, to sail downstream.
I'd need to wait for North Westerly winds that would blow more
reliably down the river. I set my course for the Point.
It was not an easy sail to reach the West End Bridge. This short
stretch of river has the most erratic winds. In the time it took me
to sail to that bridge, I experienced periods of dead calm and winds
from every direction. At one point, a strong gust blew from the North
East, exactly the opposite direction of the overall winds. I managed
to set my sail to catch it and shot along the river for quite some
way with it.
Once I passed the West End Bridge, I was in clearer water. The
South Westerly winds took over. I let the sail out and they drove me
directly up the Allegheny. With winds this sure, it was my
opportunity to sail farther up the Allegheny again. The winds were
quite strong, so it was a fast sail. Here's the GPS track of my sail
from 1:15pm to 2:10pm:
click for larger
I covered a lot of river in a short time. Allowing for the delay
in getting started, it took perhaps 30-35 minutes to reach the
farthest point, the 16th Street Bridge. I dared go no farther since I
knew I'd have to tack home laboriously and that would take much
longer than my easy run. I was also looking for an easy place to stop
and beach.
There proved to be a little rocky beach just upstream of the 16th
Street Bridge. I steered into it, jumped out into the river shallows
at the edge and hauled my boat over the rocks onto the shore.
Here is the rocky shore:
...and the bridge span overhead
It was hot and I'd worked pretty hard. My water bottle had been
calling me for a while, but I had no hands for it. Now finally I
could open it. There was also time to dig my lunch out of the hatch.
It was modest, a granola bar and a little bag of pistachio nuts, but
somehow very satisfying for having been well-earned.
I was weary. Although I didn't know it, the weather (view actual
conditions here) was proving hotter
than forecast and the temperatures had risen past 90 degrees.
It was time to put back into the water. So I set the rigging and
started to push the boat out. Instead of sliding elegantly into the
water, it sprang back. I pushed again; it sprang back again. It was
as is some river nymph was warning me magically not to enter the
river.
Puzzled, I looked up and the mystery was solved. It was not a
supernatural event. In beaching the boat, I had tangled the mast in
overhead trees. Leaves and little branches fell as I pulled the boat
free.
Now I was back in the water. It has been an easy sail upstream and
I'd sailed a long way. Now I realized that I was going to pay a price
for that ease. The winds on the river were quite strong and stronger
than I'd remembered in the sail upstream. I could see little
whitecaps forming and a quite substantial chop had developed in the
water's surface.
What I did not realize until then was that the wind forecast was
wrong. This time it had predicted much less wind than now blew over
the river. While I didn't then know the number, the top wind speed
had now risen to 20 mph and more, as the record of actual conditions shows.
That meant that I was struggling with winds at the river surface that
gusted from virtually nothing all the way up to over 20 mph.
It was difficult sailing. I would need to sail all the way home
directly into these winds. Sailboats can sail into the wind. They
just tack to and fro, as I explained here. But the stronger the
wind, the harder it gets.
When a sailboat is running, the wind blows from behind it and its
sails are let out to catch the wind. The force of the wind presses
the boat directly forward.
When a sailboat sails across the wind, a "beam reach," the wind
blows from the boats side ("beam") and its sails are set to deflect
the wind to the boat's rear, so the boat is pressed forward by the
pressure of the wind on the sails.
The same mechanism enables the boat to sail into the wind. Here is
the configuration for a "close hauled" sailboat, that is one that is
sailing a course as close to the wind as possible.
To deflect the wind usefully, the sails are now pulled in quite
close to the boat. If they aren't pulled in that close, they would
just flap uselessly in the wind.
This need to pull the sails in to make way against the wind is the
problem. For now virtually all of the force from the pressure of the
wind is directed across the boat and is acting to tip it.
In light winds, this is no problem. In modest winds, the sailor
just sits on the windward side of the boat and that is enough to
balance things.
In heavy winds, the sailor has to hike out, throw his or her body
over the windward side of the boat, to balance the boat. If the winds
are steady, that is an exciting part of sailing. The boat flies over
the water, while you hover inches from its surface.
In the conditions now prevailing on the river, however, it is an
ill-advised maneuver. The winds come in gusts. That 20 mph blast may
last one or two seconds or ten seconds; and then be followed by
nothing. In those conditions, there is little room for error. If you
don't hike out far enough, you won't counterbalance the wind
sufficiently. The wind will overbalance the boat and you will end up
in the water. If you are hiked out far and the wind dies suddenly,
you may overbalance the boat in your direction and end up in the
water. Either way, you then have to right the boat in heavy winds,
hoping you don't get blown into weeds on the riverbank and that no
big boat lumbers down upon you.
As I tacked to and fro into the wind, I took the timid approach.
I'd let the sail go with each blast, so the sail would flap uselessly
and not tip me. All this slowed my progress and kept me busy on deck,
releasing and hauling in the mainsheet (the rope that controls the
sail).
Then there is a second problem. A sailboat makes way into the wind
by tacking, that is, zigzagging to and fro across the wind. Each turn
is a delicate maueuver. In the middle of the tack, the sailboat is
pointing directly into the wind.
At this moment, the sailboat is unpowered. The sail is flapping
uselessly. All that keeps the boat moving and turning is its inertia.
In heavier winds, that is, in winds over 10mph, I learned that the
Bravo is a tough boat to tack. As soon as it has lost wind power, the
head wind commonly slows the boat enough so that it doesn't make the
turn. If the water is choppy, as it was on this stretch of the river,
that compounds the problem. The waves come head on with the wind and
their repeated slapping against the hull slows the boat more.
A common outcome is that the tack is missed. The wind blows the
boat back and you must continue on the original course, even if
there's no more river to sail in. Sometimes the tack can be saved by
reversing the rudder as the wind pushes the boat back. The operation
is rather like backing up a car. But you must have come close to
passing the eye of the wind already for this trick to succeed. In
heavier winds, I've found it too little to save most failing
tacks.
As I said, this was difficult sailing. Time and again, I was
forced to "jibe." Instead of taking the bow across the wind to make
the tack, as shown on the left, I'd steer away from the wind and pass
the stern through the wind, as shown on the right, making a full 270
degree turn.
It is not an elegant maneuver, especially in heavy winds. The boat
takes off rapidly on a run and then, as the stern passes the eye of
the wind, the sail snaps over to the other side. You have much less
control during jibing. When the winds are heavy, you want more
control, not less.
I did what I had to, to get home. Here's the GPS track for the
first half hour from 2:30 to 3:00pm:
click for larger
You can see how often I jibed by the little loops in the track.
This was exhausting and difficult sailing. I was constantly reacting
to treacherous winds and being shaken by the continual slapping of
the chop against the hull. I needed all the space I could get to keep
making progress against the wind. Navigating around other boats is
usually an interesting diversion. Today it was not welcome. Mostly,
the powerboaters sensed my predicament and kept out of my way. I was
grateful to them and tried to nod my thanks as we passed.
However it did not always go this way. I was sailing close-hauled
just downstream of the Veterans' Bridge when a large power boat
approached from downwind on a course that converged directly with
mine.
Its skipper, a silver haired, stocky gentleman, stood at the helm
with friends gathered around him. The river was his domain to
command.
He looked straight at me and I looked straight at him. I wondered if
he realized how little scope I had to evade him, short of letting go
the sail to stop dead in the water. He was approaching from downwind,
the only direction I could turn. In any case, the rules of navigation
required him to make way for me. It became clear that he would make
no compensation for me. He just kept looking at me and heading
straight towards my course. Finally, he passed in front of me with a
just a few feet to spare. Fortunately there was not much wake.
A lady seated at the stern smiled awkwardly at me. It might have
been an apologetic smile for her captain's misbehavior. Or perhaps
she was just puzzled at the oddity of a sailboat on the river. I
called out something about the rules of navigation.
"Sailboats under
sail only have the right of way over power-driven vessels unless the
sailboat is overtaking the power-driven vessel or it is approaching a
boat at anchor."
Pennsylvania Boating Handbook. Chapter
4. (Pennsylvania Fish and Boat Commission.)
The next hour of sailing was the most difficult. I made rather
less progress than at any other time. The GPS track shows that I made
it only just past the Fort Duquesne Bridge. The time is 3:00pm to
4pm:
click for larger
I was growing weary of letting out the sail with each gust, of the
flapping sail, of hauling in the sheet again. It was time to "reef"
the sail. The sail of the Hobie Bravo is roller furled. That means it
rolls around the mast. It can be "reefed," that is, reduced in size,
merely by rolling up part of it around the mast. I'd already reefed
the sail in my initial leg upstream as I ran before the wind. It was
easy to do. There's a blue furling line wrapped around the mast and
all you need to do it pull on it, if you can find a free hand and
reach to the front of the boat.
Reefing the sail would reduce the likelihood the the wind tipping
the boat, so it started to look attractive. The final straw came when
I missed a tack under the 6th Street bridge and sailed into the
Southern bridge piling. It was not a major collision. It was just a
little bump. Seeing it coming, I held the bow towards the wind so
that the boat moved very slowly. Then I pulled the furling line to
roll up the sail completely. I let the wind blow me back upstream.
Once clear of the bridge piling, the wind on the mast was enough to
turn the bow upstream. I let out just a foot or two of sail and
sailed slowly across the wind to the dock. There I moored and took a
short break. That maneuver and the return to the river from the dock
makes the big loop in the GPS track:
Here is the boat docked:
..and another photo.
The sailing was less tense with the sail reefed. I could even
"cleat" the mainsheet. That is, I could lock it in a clamp that is
part of the block (pulley) through which it runs. That meant that I
didn't have to hold back the tension on the sheet. You would not
normally do that in heavy winds, since you have to be able to release
the sheet instantly if there is a big gust of wind.
The bad side of a reefed sail, I soon found, is that it makes
tacking in heavy winds even harder. A reefed sail provides less drive
to give you the inertia to pass the eye of the wind. Also, in this
case, the sail is so cut that when reefed it is no longer shaped
optimally to let the boat sail close to the wind. I was now sailing
slower and further off the wind. I had no choice but to jibe.
Here's the last leg of my voyage, from 4:00pm to 5:pm:
click for larger
I made much better progress than in the hour before. There was
much less chop than there had been higher up the Allegheny. Shallower
waters produce higher waves. I wondered if that is what was making
the difference. However it was not all plain sailing. Each little
tangle in the GPS track represents a shift of wind that left me
sitting momentarily without motion trying to figure out where the
wind had gone. Indeed the wind continued to be variable all the way
home. For a while, the wind seemed to die off to a slight breeze.
Then I sailed with the sail fully unfurled, until the heavier gusts
returned.
When I passed the West End Bridge, I found the wind blowing
through the valley and spilling Eastward toward home. (I'd now come
not to be surprised by this--see here.) I took the winds for an
easy run back. At the last moment, just as I was about to turn into
the dock, a sudden gust nearly spilled me into the water. As I hauled
the boat out of the water and unrigged it, I noticed that now the
winds were blowing steadily in an Easterly direction, the exact
opposite of how they blew at the start of the sail. A few minutes
later I looked at the small flags on the docked boats. Now they had
the winds blowing from the West. In this stretch of the river, when
the winds have a Southerly component, you can take nothing for
granted!
Here are the full gps tracks:
click for larger
click for larger
Finally, the plot below is color coded for speed. Note that the
legend is in kilometers per hour. I'd estimate that the plot records
a maximum speed of 14 km/hour. That corresonds to around 9mph and
that is the maximum speed I'd noted by glancing at the GPS receiver
as I sailed.
click for larger
I was really quite exhausted after this sail. It took some effort
to unstep the mast and stow all the gear. Finally I was heading off
home on my bike. I stopped at various points to measure the wind (at
the casino, at the pier at the Del Monte building, on the Sixth
Street Bridge). I measured winds varying from 5mph to just over 20
mph in sudden gusts. That fitted with the report of actual conditions, near enough.
While I was exhausted from a mighty struggle with the wind and
water, the rest of Pittsburgh was feeling quite festive. There was a
Pirate's baseball game starting up. The riverfront was lined with
boats and a river ferry had just arrived, disgorging a crowd.
It was after 6pm by the time I had my bicycle stored away and
could sit down to see the latest weather report: 92 degrees! No
wonder I was worn out. But I wasn't quite worn out. So I put on my
running shoes and returned to the river trail for a 45 minute run up
to Herr's Island (now Washington's Landing) and back. I've decided
that I'm a triathlete of a lesser sort. These days are a triple
event: sailing for four hours; cycling four miles; and running forty
five minutes.
John D. Norton
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