TBMS 2012

TBMS 2012

The 15th annual Tampa Bay Marathon Swim is this Saturday! TBMS is – I think it’s fair to say – the toughest organized swim race in the United States.

tampa bay marathon swim
Five minutes before the start of TBMS 2011. Photo by Distance Matters

New this year, the race will have live GPS tracking. I’ve also agreed to provide some color commentary on the official TBMS Twitter account – follow @DistanceMatters if you’re interested. For those following the GPS tracking, here are two paths from last year’s race: mine, and Bob Needham’s (1, 2, 3).

Current weather forecasts call for a 60% chance of rain (possible thunderstorms), with 10-15mph winds out of the SSW. That’s a favorable wind direction, but let’s hope the lightning stays away.

Best of luck to all the swimmers!…

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Adventures in exercise physiology: Tampa edition

Adventures in exercise physiology: Tampa edition

Best I can tell, I lost about 1 pound of body mass during the Tampa Bay Marathon Swim. Actually – probably closer to 1.5 pounds, but we’ll call it a pound. Marathon swimmers often lose substantial weight over the course of a swim, but most of this is water loss that is soon regained. I estimate that I lost a little over a pound of body mass – that is, fat (and possibly some protein cannibalized from my muscles). For convenience, we’ll call it a pound of fat.

Some back-of-the-envelope calculations:

Losing a pound of fat requires an energy deficit of 3,500 calories. I consumed 2,800 calories during the swim. That puts my total energy expended during the 9-hour swim at 6,300 calories — 700 calories per hour.

This tells me a couple of things. First, my energy expenditure is higher than I expected. 700 cal/hr is the typical estimate for “vigorous” swimming – but this was my ultra-marathon pace. Second, I can probably experiment with raising my calorie consumption. I took 311 cal/hr in Tampa, but when I’m burning 700 cal/hr that puts me in deficit within, at most, 5.1 hours (assuming 2,000 calories pre-stored glycogen), and possibly as little as 3.8 hours (assuming 1,500 calories glycogen).…

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Race Report: Tampa Bay Marathon Swim

Race Report: Tampa Bay Marathon Swim

Part 1: The Team

Without a team, a 24-mile swim doesn’t happen. Simple as that. And the swim’s success – it’s efficiency – depends on the quality of the team. Long swims are isolating experiences: A swimmer and his thoughts. But there’s an irony: The longer the swim, the more you utterly depend on your support team.

So any discussion of my experience in Tampa Bay must begin with my team.

The Team (L-R): Kathy, Carl, Pat, Michael, Kim… Frankland Bridge in the distance. (Photo Credit: Distance Matters)

It’s tough to overstate how fortunate I was.…

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On “ultra”

On “ultra”

NOTE: I wrote this as preface to my Tampa report, but it got a bit long so I decided to put it in a separate post. It’s not really specific to Tampa, anyway.


What’s a marathon swim? Without any historical reference point (as for marathon runs), there are various definitions. The official FINA and (as of 2008) Olympic distance is 10K – which has the virtue of similar finish times as marathon runs. Penny Lee Dean sets the bar at 16 miles. Ted Erikson says 10 miles. Steven Munatones, as usual, wrote a nice overview of the issue.

I’m not really interested in debating what is or isn’t a marathon swim, though I do think:

  • It must be in open water.
  • It should be nearly impossible (or at least very difficult) to finish without refueling mid-swim.
  • It should be very difficult to accomplish without support.

So, I’m fine with calling 10K a “marathon swim.” What about 24 miles, though? Typically, that’s described as an “ultra marathon swim.” My reason for discussing semantics here is, there’s something about a swim of that distance that’s not captured by merely adding the word “ultra.” A 24-mile swim is qualitatively (not just quantitatively) different than a 10K.…

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Tampa, in brief

Tampa, in brief

I thought I should get something out now (however brief), with a more comprehensive report to follow. Yesterday was an experience that… will take a couple of days to process.

I fulfilled my goal of finishing the Tampa Bay Marathon Swim. The time (8:59) and place (1) were nice, but finishing was the hard part.

A few stats (some actual, some approximate):

  • water temp: 80F
  • air temp: 70F (low) to 88F (high)
  • wind speed: 15 mph (morning) to calm-ish (afternoon)
  • calories consumed: 2,800
  • calories burned: 5,000+
  • fluids consumed: 320 oz (9.5 liters)
  • strokes taken: 33,500 (a few on my back, for various reasons)
  • pace per mile: 22:27

Here are the data from the GPS transponder on my escort boat (ignore the blue line):

Credit my boat pilot for that incredibly true line. More on him later.

If you’re wondering about the detours at the bridges, that’s because certain portions of those bridges are too low for the boat to pass under. Specifically, the parts crossing over the shortest path to the finish. So the boat went around to find higher clearance, while my kayaker and I went under.…

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Don’t underestimate Tampa

Don’t underestimate Tampa

Some people do the Tampa Bay Marathon Swim as a “warm-up” for one of the triple crown swims. And it makes sense: Tampa is early in the season, 8 weeks before MIMS and more than 3 months before high season for channel crossings.

But thinking of Tampa as a “warm-up” might tempt a person to take it less seriously – and that would be a big mistake. TBMS is one of only four annual organized ultra-marathon (25K or longer) swim races in the U.S. (along with MIMS, Ederle, and Swim Across the Sound), and it may be the toughest. While water temperature is not usually a factor, pretty much everything else is. Glancing through the archives, tide changes and rough seas seem to be the two big ones.

Swimmers typically start with the flood tide, which pushes them up Tampa Bay — for a while. If you don’t swim far enough over the next few hours, though, the tide reverses direction and starts to push you back towards St. Petersburg – making it effectively impossible to finish.…

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