SWOLF (“swim golf”) is a drill that measures swimming efficiency. A SWOLF score is your time (in seconds) on one lap of the pool, added to the number of strokes you took. Lower scores = Higher efficiency. SWOLF is a fuzzy, indirect measure of efficiency, because stroke count doesn’t necessarily reflect effort. In my view, the most precise definition of SWOLF is that it identifies the most efficient stroke count for a given level of effort.
I originally wrote about SWOLF in April 2012, and the post has become – by a wide margin – the most widely-read in the history of this blog. In a subsequent post a month later – “Stroke Count Games” – I described how SWOLF doesn’t quite capture the most efficient stroke count.…
One year (and one week) ago, Donal and I launched the Marathon Swimmers Forum with the following mission statement:
- To celebrate and promote the sport of marathon swimming.
- To foster connections and information sharing among the global community of marathon swimmers.
- To provide an educational resource for aspiring marathon swimmers.
Donal and I are both pretty proud of what’s happened since then. Just by the numbers, 565 confirmed members have contributed 5,437 posts in 400 separate discussion threads. Even better, the quality of the contributions has been gratifyingly high.
To celebrate the Forum’s first birthday, here’s a quick peek at the site analytics:
A Global (yet, to be honest, mostly anglophone) Community
Geographical distribution of visits by city
Geographical distribution by country, full year
Geographical distribution by country, first month
Everybody Loves a Controversy
Top Threads, as measured by pageviews:
Google has a fun tool that lets you visualize trends in search queries submitted by its users. Google is often the first place people go to find out more about a given topic, so it’s a powerful measure of the public’s “interest” in that topic. Below are a few Google Trends graphs related to open water swimming.
Is open water swimming “growing”?
search term: “open water swimming”
- Interest in open water swimming is highly cyclical, with summer peaks and winter troughs. (Obviously.)
- Two big “spikes” corresponding to the Olympic Games in 2008 and 2012.
- Aside from the seasonal cycles and Olympic spikes, the peaks and troughs do seem to rising slightly over time.
What about two sub-genres of open water swimming: marathon swimming and triathlon swimming?
In case you missed it:
The shortest-line distance from Santa Cruz Island to the mainland is 16.4 nautical miles (18.9 statute) – starting at San Pedro Point, finishing at the southern end of Hollywood Beach, north of the entrance to Channel Islands Harbor. Capt. Forrest actually plugged in a slightly more distant waypoint – the resort at Mandalay Beach – which made it a 16.6-nautical mile swim. I don’t know why, but that’s what he did.
To break Ned’s record, I had to average 1.59 knots (2:02 per 100m, 2945m per hour) across the channel. To break 10 hours, I had to average 1.66 knots (1:57 per 100m, 3074m per hour). My neutral-condition (i.e., pool) pace for a swim of this distance, at my current fitness level, would be approximately 2.3 knots initially, fading gradually to ~2.05 knots.…
There are 14 years of publicly available data on the surface water temperature in the Catalina (a.k.a. San Pedro) Channel – via NOAA and CDIP. Unfortunately, that’s all it is – data. No summary statistics, no long-term charts – nothing particularly useful if you’re just looking for a simple, big-picture view of trends and cycles in sea temperature (perhaps to inform your upcoming swim across the channel).
So I decided to make one myself:
NOAA buoys take readings every 30 minutes. Over 14 years, that works out to almost 239,000 observations. Don’t try this on an old computer! For a smoother line, I calculated a weekly average. Same data – just prettier.
If you really need more detail, I also made an interactive chart with daily-level resolution (5,044 observations).…
Previously, we’ve looked at some general stats on Catalina Channel finishing times, and the growth in participation since George Young’s pioneering swim in 1927. What about gender differences? (Taking a page from Katie’s playbook…)
From 1927-2004, there were 90 successful swims by men and 44 successful swims by women (a ratio of 2.05 to 1). From 2005-2011, there were 80 successful swims by men and 49 successful swims by women (a ratio of 1.63 to 1). So, the gap is narrowing…a bit.
Here, again, it would interesting to see the data on failed swims. Is the ratio of men to women the same for failed swims as for successful swims?
Side note: I decided to split the data-set at 2005 because it offered similarly-sized groupings, and because this was the year when there was a surge in popularity of Catalina Channel swimming (possibly due to the advent of the “triple crown”).…
The second in a series of posts taking a statistical look at the history of Catalina Channel swimming. These analyses have not been validated or endorsed by the Catalina Channel Swimming Federation and should be considered “unofficial.” 2011 swims are included, but are unofficial until the ratification banquet on November 5.
CCSF’s official list of successful swims is available here. Penny Lee Dean’s authoritative history is here.
On January 15, 1927, George Young was the only one of 102 participants to finish the Wrigley Ocean Marathon, and in so doing, became the first person to swim across the Catalina Channel. For his achievement Young earned a $25,000 prize – approximately $325,000 in 2011 dollars, and richer (even in nominal dollars) than any current cash prize in professional marathon swimming.…
The first in a series of posts taking a statistical look at the history of Catalina Channel swimming. These analyses have not been validated or endorsed by the Catalina Channel Swimming Federation and should be considered “unofficial.” 2011 swims are included, but are unofficial until the ratification banquet on November 5. CCSF’s official list of successful swims is available here.
I should note that Penny Lee Dean did some similar statistical work in her authoritative History of the Catalina Channel Swims Since 1927. However, the book has not been updated in 1996, and in any case, the stats chapter seems to have been removed from the online version.
The Catalina Channel was first conquered in 1927 by George Young of Canada, in 15 hours, 44 minutes, 30 seconds. …
When I boarded the Bottom Scratcher the night of August 24, the first thing I did was plug in my phone and activate the Instamapper GPS tracking app.
Why was this the first thing I did? As most of my readers must know by now, I have as much fun (probably more fun, actually) analyzing marathon swims as actually doing marathon swims. Hence my six-part MIMS report.
As usual, the data tell an interesting story. The yellow path shows the GPS tracks of the boat which, except at the start and finish, was between 5-25 meters off my left side. The red line shows the straight-line “ideal” path between the start and finish. The white placemarks are self-explanatory.
I covered the first 5 miles in 2:06:50 (25:22 per mile), my fastest pace of the swim despite big swells and chop throughout the night.…
Behold: the water temperature (in degrees F) and wave height (in feet) in the Catalina Channel over the past 45 days, taken at half-hourly intervals:
Fingers crossed for some smooth water tomorrow night!
Shelley Taylor-Smith recorded the fastest swim around Manhattan (5:45:25) in 1995, but it was a special “record attempt” swim scheduled on an unusually fast tide. What are the fastest swims in the regular Manhattan Island Marathon Swim race, which is typically held on a slower tide? Over the 29 years of the modern MIMS, the 10 fastest swims are as follows:
- Tobie Smith, 1999, 6:32:41
- Tammy van Wisse, 1999, 6:51:31
- Rob Copeland, 1999, 6:52:49
- Susie Maroney, 1990, 7:00:27
- Matthew Nance, 1990, 7:04:53
- Jim Barber, 1991, 7:06:34
- Kris Rutford, 1991, 7:06:44
- Matthew Wood, 1990, 7:07:32
- Susie Maroney, 1994, 7:08:10
- Igor de Souza, 1991, 7:08:20
Interestingly, 9 of the 10 fastest times happened in just 3 years – 1990, 1991, and 1999. The 3 fastest times were all in one year – 1999.…
It’s well known that Shelley Taylor-Smith holds the record for the fastest swim around Manhattan: 5 hours, 45 minutes, 25 seconds.
What’s not quite as well known is that she achieved this feat on a special “fast tide” – a convergence of maritime conditions in the East, Harlem, and Hudson Rivers that occurs only once or twice a year, if at all.
With the founding of the modern Manhattan Island Marathon Swim race in 1982, and more sophisticated understanding of tide cycles, a string of specially planned solo “record attempt” swims were undertaken in the ’80s and ’90s, all on fast tides. After Diana Nyad‘s 1975 swim in 7 hours, 57 minutes, the record was lowered six times by four different people over the next 20 years:
- 7:14 – Drury Gallagher in 1982
- 6:48 – Paul Asmuth in 1983
- 6:41 – Drury Gallagher in 1983
- 6:12 – Shelley Taylor-Smith in 1985
- 5:54 – Kris Rutford in 1992
- 5:45:25 – Shelley Taylor-Smith in 1995
Her record has stood ever since, despite an assault last year by world-class marathon swimmers Petar Stoychev and Mark Warkentin.…
Among swimmers, runners, cyclists, weightlifters – really, any athlete in a quantifiable sport – it’s common practice to keep a training log. In high school and college, I kept a log only sporadically – and I really regret it now. I’d love to look back on some of the sets I did in those days.
Since I got back into swimming a year and a half ago, I’ve been much more conscientious about keeping a log, and I think it’s really helped – motivating me to get to practice, and helping me gauge progress. I split my training log between two documents: a text file where I write what I did in each workout (sets, intervals, times, etc.), and a spreadsheet where I log the total distance I swim each day.…
Have you ever wondered…
How many [yards] can I swim in [4 hours] if I hold a pace of [1:15] per [100 yards] … and you wanted an answer right now? Perhaps you didn’t have a calculator handy, or didn’t want to fire up Excel… or maybe you just didn’t feel like thinking very hard.
Or, perhaps you have wondered…
If I swim [10K] in [2 hours, 45 minutes], what is my pace per [100m] ?
In conclusion: Bing sucks, people.*
* Full disclosure: I am a former employee of Google.…
This chart compares the average MIMS finishing time over the years for Men vs. Women (click to enlarge):
Interestingly, the average female MIMS finisher was faster than the average male in about 80% of the years. Men were faster only in 1982. (The remaining years are statistical ties.)…
Five months until MIMS! In the meantime, some data porn for your enjoyment (click to enlarge):
The NYC Swim website has MIMS results as far back as 1915, but the modern version of MIMS as an annual marathon swim race began in 1982, when Drury Gallagher founded the Manhattan Island Swimming Association.
The chart above shows every MIMS finishing time from 1982-2010 (black dots), along with the slowest, fastest, and median time of each year (blue, green, & red lines, respectively). Only participants in the annual MIMS race are shown – no solo attempts (e.g., Shelley Taylor-Smith’s record swim of 5:45 in 1995).
People say times don’t matter in open water – or at least that you don’t always know what they mean. And perhaps that’s part of its attraction. While in the pool “the clock never lies,” in open water it’s not much more than a ranking device.
Even so, I’ve been surprised by how closely most of my open-water pace times have approximated my pool speed at various distances – from 1:15 at 1 mile (Huntersville), to 1:17 at 1.5 miles (Livermore), to 1:19 at 2 miles (H’ville again) up to 6K (Windsor), and 1:22 at 10K (Noblesville).
When an event has been staged for many years, though – at the same location, on the same course layout – comparing times makes a little more sense. Big Shoulders is one such event.…
In the first 8 months of 2010 I swam 452.4 miles (796,224 yards). Here’s the mileage by month, with days out of the water: 52.1 (7 days off), 52.8 (2 days off), 63.7 (3 days off), 60.0 (4 days off), 45.7 (8 days off), 64.1 (5 days off), 52.9 (6 days off), and 61.2 (6 days off).
I’m pretty happy with that consistency. The only somewhat anomalous month was May (45 miles), during which I got sick and missed 6 days in a row right before Atlanta Nationals.
This coming month will be an important one in preparing for the 10-mile swim on October 16. Assuming I stay healthy (fingers crossed), I have a soft goal of 75 miles (132,000 yards) for September.…
More Big Shoulders stats, from my custom-made aggregate file. Here’s the proportion of Big Shoulders participants hailing from Illinois, Indiana, and “other” – i.e., anyplace besides IL and IN.
Clearly, Illinois locals still predominate, but recent years have seen a greater influx of out-of-state swimmers. In 2009, almost 30% came from outside of Illinois and Indiana – an all-time high.…
More fun with Big Shoulders stats. We’ve been looking at participation – so what about age? Masters swimming is traditionally dominated by people in their 40′s and 50′s – is the same true here?
It seems the modal age is actually a bit younger in Big Shoulders – lots of people in their 30′s. But the “50′s” have been mounting a furious comeback (see the blue line) – perhaps a baby boomer effect.
My custom aggregate CSV file, from which I calculated these stats, is available here.…