Lake Erie, Colder Water, and Current Study

Over the last month I've been working harder than usual to fix my overall swim form to eliminate my ultra-draggy kick. I made major progress determining the cause(s) but only minor progress fixing it. I want to discuss it at some point, but my long swim in Lake Erie on Saturday was much more interesting to write about, especially the bizarre effect of current that showed up on video.

Saturday was a perfect day for a long swim in the lake. Several days of good weather meant the lake would be (relatively) clean, it was warm and mostly sunny, and winds were calm. My husband Jim accompanied me in his kayak so I could practice my feed routine. Any chop we encountered came mostly from boats and jet-skis in close range. in addition to getting a long swim with feedings, I wanted to learn how to and if I could swim comfortably in colder temperatures for a long period of time. Based on buoy readings, the water was 70 degrees F or just under - perfect for a beginning study. Most cold-water swimmers would laugh at this temperature, but I have to start somewhere, and the water will only get colder from here as air temperatures drop.

Some photos from the morning:

And the Lake Erie surface temperature profile around the time we started:

I was able to swim for three hours comfortably. After an hour, I began to fight numbness in my fingers, but I had no sense of cold overall, i.e., my core temperature wasn't dropping. I constantly reminded myself of advice gleaned from open water swimmers' blogs and forums: don't stop for more than 30 seconds to feed, and get used to discomfort in fingers and toes because that goes with the territory. If you can't learn to like it, at least learn to tolerate it. No matter how numb my fingers got, I could still manage a good underwater pull - this was a victory in my book. And it didn't get progressively worse because I found that intermittently making a fist would cause some blood to flow back into my fingers. Surprisingly, my feet and toes remained comfortable through the entire swim (unexpected since I kick very little).

The more interesting and difficult part of the swim resulted from the course we took. We started out heading east, against the current, and turned around after 40 minutes when boat traffic picked up near the mouth of one of the rivers that flows into the lake. When we turned, I looked at my watch to see my average pace was around 1:43 (per 100 yards). We now headed west back to our starting point - which we reached at 1:16. Swimming with the current now was four minutes faster. From the starting point we now went west for 44 minutes - until we hit two hours. And then, when we turned around to head back (east), against the current, it took over an hour to get back to our starting point. It was more than 16 minutes slower coming back on the second out-and-back loop, yet the distance was only about 0.2 miles more than one leg of the first loop.

Here's the route on a Google map: 

It certainly felt like the final return leg was against a stronger current that the first, but I had a hard time believing things changed that quickly. So afterwards, I checked the Lake Erie current profile by the hour during the time I was swimming (2:20-5:20) and here's what it showed (note: my swim location was the bottom of the little dip just to the left of the date in the map of Lake Erie):

2:00 pm:

3:00 pm:

4:00 pm:

5:00 pm:

6:00 pm: 

So, there it is, current conditions changed drastically from the start to the finish of my swim.

After the swim, Jim told me something interesting. He said when I was swimming WITH the current, it looked like I wasn't moving at all. But when I was swimming AGAINST the current, it looked like I was going really fast. How could this be so noticeable? Later, while looking at the videos he took from the kayak, I was shocked to see exactly what he had described. Check it out: