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.…
Marathon swimmers talk a lot about rules – what should and shouldn’t be allowed during a swim – but as far as I know, there has never been any systematic study of what marathon swimmers actually think, as a matter of public opinion.
Perhaps most would agree that goggles are OK, and fins are verboten… but what about swim streamers and stinger suits? Or drafting off the escort boat? If you only read blogs and forums, you might assume the most vocal opinions represent the majority. But do they really?
Earlier this month the SBCSA launched a survey to find out. Over 25 days, we received 175 responses from around the world.
First, a Summary of Findings (TL/DR). Click any of the following links to skip directly to the relevant section.…
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?
Everyone knows wetsuits help keep you warm in cold water. Lesser known among the general public (but well-known among triathletes) is that wetsuits also make you swim faster! The buoyant neoprene in a wetsuit floats a swimmer higher in the water, decreasing drag and thus increasing swim speed.
But how much faster is a wetsuit? I’ve heard various rules of thumb: 10% speed increase; 4-6 seconds per 100m; 1 minute per kilometer. I’ve also heard various caveats: it depends on the swimmer’s skill (better swimmers benefit less); it depends on the swimmer’s body-type (naturally floaty people benefit less); it depends on the quality of the wetsuit (you get what you pay for); it depends on the fit of the wetsuit; and so forth.
So the answer is: It depends.…
What’s the fewest number of strokes you can take for a single length of the pool? (No streamlining past the flags; no more than three kicks per stroke.)
I can get down to 8 strokes per 25 SCY, but it’s tough to sustain for more than one length. 9 strokes per length (SPL) I can do pretty much indefinitely – but it’s incredibly inefficient. The inefficiency is readily apparent: a huge dead spot in my momentum as I glide (glide, glide…) after each stroke. The Swim Smooth guys have a term for this: Overgliding.
I swim most efficiently between 13 and 15 SPL, depending on pace. 13 for channel/marathon pace; 14 for “threshold” pace (from the mile up to about 5K); 15 for 200/500 pace.…
There’s an old saying about cold-water marathon swimming:
Either be fat, or be fast.
Is it oversimplified? Probably. Crass? Definitely. But there’s a kernel of truth worth examining. Thin swimmers have made it across the English Channel, but they’re usually fast. Slow swimmers have made it across the Channel, but they’re usually… carrying a healthy layer of bioprene.
The common factor: Core temperature must be preserved. Either generate heat, or retain it. Fast swimmers are good at generating heat. Fat swimmers are good at retaining it.
In the English Channel (from what I gather), it’s considered prudent for non-overweight swimmers to put on some weight, even if they’re “fast.” A Channel attempt is expensive and, unless your name is Petar Stoychev, just getting across is the main priority.…
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. …
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!
Readers may be curious to see split times for the full rivers (East, Harlem, & Hudson) – not just the “segments” shown in the previous two posts. So here they are.
You’ll notice a new swimmer in the mix here: Sarah Thomas from Colorado. Originally seeded 8th, Sarah managed to slip into 5th place overall with a roaring swim down the Hudson. Well done, Sarah!
In the “GPS snapshots” I’ve shown in the last couple posts, you can see how far apart each swimmer is (6 of them, anyway) in terms of distance. Four hours into the race, for example, Erica Rose was 455m ahead of Ollie Wilkinson, who was in turn 135m ahead of John Van Wisse.
Another way to model the race is to look at when each swimmer passes a given landmark. This shows how far apart each swimmer is on a different dimension – time. Using the GPS tracks provided by NYC Swim, we can actually calculate “split times” for each swimmer between any landmark we choose. And, using those split times, we can calculate each swimmer’s speed (including current) for each segment.
For the purposes of this study, I chose 11 landmarks – three in the East River (Pier 11, Queensboro Bridge, and the Randall Island footbridge), two in the Harlem (Macombs Dam Bridge and Spuyten Duyvil), and six in the Hudson (GW Bridge, Riverbank Park, 79th St, 34th St, Pier 40, and the finish at South Cove).…
Just over a week ’til the Manhattan Island Marathon Swim! Hard to believe it’s already upon us.
Sometimes people ask me if I have a “goal time” for the swim. That’s an interesting question. As anyone who’s spent much time in open water knows, the relationship between time and distance is somewhat complicated; even moreso for marathon swims.
MIMS is a different beast, though. I’d go so far as to say that MIMS times are pretty much meaningless — as an indication of speed. The typical winning time of 7 hours, 30 minutes works out to just under 59 seconds per 100m. So: world record 1500m pace, 28.5 times in a row. In MIMS, the tides are king – perhaps moreso than any other major marathon swim.…
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.…
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.…
Many open-water swimmers seem to have origin stories. A moment of revelation when one identifies – in a powerful and lasting way – with the experience of being in open water. In reality it’s usually more of a process than a single moment, but often there’s a particular event that seems to crystallize that process and lend it symbolic meaning (perhaps only retrospectively).
One of the great legends of open water swimming, Lynne Cox, turned her own origin story into an award-winning book. Cox’s story, too, was a process – but she also describes a moment from which the rest of the moments in her incredible career seem to flow. In 1971, she entered the Seal Beach Rough Water Swim and, as a 14-year old, won the women’s race and beat all but two of the men.…
If you like gadgets and/or swim toys you may have found yourself, at some point over the past couple of months, drooling over the FINIS Swimsense Performance Monitor. And after playing with one for a few weeks now, I’ll admit, it’s pretty cool.
Before you fork over $200, though, consider the question: What does the Swimsense – and swim watches in general (e.g., the Swimovate Poolmate and Oregon Scientific’s watch) – offer that a simple pace clock doesn’t?…
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.)…