Sunday, April 1, 2018

Computers don't compute everything

Yesterday's weather was breezy but otherwise lovely.  When I got down to the riverfront the sun was out and the Fahrenheit temperature was in the mid 60s and rising toward a high in the low 70s.  I warmed up and did three 8-stroke sprints, and then practiced my strokes at varying levels of intensity.

It was overcast and cooler when I got in the boat today, but the conditions were the calmest they'd been all week.  It would have been a good day to paddle around the Loosahatchie Bar again, but having done that some four times already in 2018, I'm a little weary of it.  I decided to stay on the Tennessee side instead.

I warmed up and did three 8-stroke sprints in the harbor, and then headed up the Mississippi.  The paddle upriver was slow-going: at the current water level (24.6 feet on the Memphis gauge) there was a lot of swirly water along the bank but not many eddies to paddle up, and the north wind was blowing just hard enough to make me feel like I was fighting a bit.  But I made it to the mouth of the Wolf River, and I figured the bottom section of the Wolf would be a good place to do a workout with my G.P.S. device.  When the Mississippi is high like it is now, it backs up the Wolf for several miles and the water there is basically flatwater.  That's what I'd always thought, anyway.

The plan was to do a four-minutes-on-four-minutes-off sort of thing, with the target pace for each "on" piece being about 7 miles per hour.  But once I got started I found it very difficult to go more than 6.8 or so.  I figured the wind had something to do with it, but even in places where I had good protection from the wind I struggled to hit 7 mph.

I paddled two miles up the Wolf, or about two tenths of a mile above the Danny Thomas Boulevard bridge, and then turned around.  Coming back downriver I suddenly had no trouble at all going 7 mph; in fact, at times I exceeded 8 mph.  Now, anybody reading this will tell me the obvious explanation--that there was in fact some current.  But each time I paddled under a bridge I took a close look at the pilings and couldn't see any eddy lines coming off them.

I was quite puzzled about it all until I took some time to do the arithmetic in my head.  Going up the Wolf my speed had been 6.5ish and coming back down it was 8.0ish, so the water must have been moving only about three quarters of a mile per hour, and that might not be enough to create any visible eddy lines.  If I'm right about that, then my speed during the "on" pieces was in fact 7.2 or 7.3 mph, and that's pretty much what I'd wanted to do in the first place.  In any case, today's experience was a good example of why I don't rely too heavily on a G.P.S. in my training: it's hard to get reliable information from it when you're doing an outdoor wilderness type of sport, even when the conditions seem as ideal as can be.

In all I did six cycles of the workout.  The sixth piece actually took me back out onto the Mississippi, and on that mighty river I could go much faster: I got it up as high as 12.7 mph... world class, baby!

I was plenty tired by the time I was back in the harbor.  I tried to relax and take good strokes all the way back to the dock.  I listened to the baseball game as I drove home.  Those mean old Mets had beaten the Cardinals twice to open the new season, but the Cardinals came back and won today.

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