FAQ + Best Practices for MSF Documented Swims

emkhowleyemkhowley Boston, MACharter Member
edited November 2017 in Resources

We've gotten a few questions lately about whether single-witness swims will pass muster to be documented by the Marathon Swimmers Federation. I'm pasting in below answers to these questions as drafted by the rules co-authors--me, Donal Buckley, Evan Morrison and Andrew Malinak)

Q: Can my swim be crewed, observed/documented, and piloted/navigated all by a single person?
A: No. Although we are sympathetic with the manpower challenges and expense of marathon swimming, MSF Documented Swims require at least two people to assist the swimmer to cover the three critical roles involved with supporting the swimmer. One role is observer, the second is navigator/pilot/kayaker who charts the course, and the third is the crew who feeds the swimmer. How these roles are assigned across a two-witness event should be based on safety considerations and common sense. If a third person is available, that’s considered ideal because then each role can be given primary attention by the individual performing it. 

The reason these roles are split across multiple individuals is because each requires specific skills and attention. It would be unsafe (and impractical) for the pilot or kayaker to be required to also observe a swim. In some instances, the kayaker charts the course and feeds the swimmer simultaneously, but they cannot also act as the official observer, not only for safety reasons, but also because of the potential for a conflict of interest. If the official observer - who is intended to be an independent, impartial witness to the swim - is also invested in feeding and guiding the swimmer, their objective independence may falter. 

Generally speaking, the more witnesses there are to a swim, the greater the credibility of the claims.

Q: Can I use a video camera as my independent observer/documenter of my swim?
A: No. Although digital media technology improves every day, we believe it will never be able to completely replace an experienced observer. This independent witness can comment on potential infractions and issues that a camera may not show. Also, GPS devices and video cameras are notorious for failing partway through a swim, and because of this unreliability, raw footage of a swim is not considered authoritative enough to substantiate claims submitted for MSF Documented Swim status as a standalone source. Video is a wonderful secondary substantiation of a swim when submitted with a thorough observer’s report from an objective, impartial witness to the swim.


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  • evmoevmo San FranciscoAdmin
    edited July 2017


    I noticed that GPS tracking data are required for all MSF Documented Swims starting this year (2017).
    But what if I don't own a SPOT tracker and/or can't afford one? And what if the tracker fails midway through the swim? Will you not ratify my swim due to a technology failure out of my control? That seems unfair.


    SPOT trackers are nice, because they provide real-time public tracking. But you don't need a SPOT tracker to record a GPS track. Any Android or Apple smartphone, or GPS-enabled fitness watch (e.g., Garmin, Suunto, Apple Watch), serves as a perfectly good GPS track recording device. See this article for details.

    GPS trackers do sometimes fail. Therefore it is always advisable to utilize multiple trackers on events where GPS data are critical for documentation. Redundancy vastly reduces the chances you will fail to get a track of your swim.

    Familiarize yourself with the technology beforehand, so you're not fumbling around during the swim itself.

    Personal anecdote: Even three years ago, on the very first MSF Documented Swim (Craig Lenning's Farallon Island swim), I was using three simultaneous trackers (SPOT, Garmin watch, and smartphone) to track the swim. Ironically it was the SPOT (usually the most reliable option) that failed -- but I had two backups, so no problem.

    Now in 2017, the technology is even better, cheaper, and more ubiquitous. With redundancy and good planning, you can nearly ensure good GPS tracking data.

  • JaimieJaimie NYCCharter Member

    Good to know! Thanks team!

  • evmoevmo San FranciscoAdmin
    edited November 2017

    Suggested Best Practice for reporting times in marathon swims

    • Record the date, time of day, and time zone of:
      • swim start (toes in the water)
      • swim finish (toes clear the water).
    • "Time of day" means:
      • hours in military format (0 through 23)
      • minutes
      • and seconds.
    • Reported times of day should be synchronized with official International Atomic Time.
      • Typically your smartphone or GPS watch should be automatically synchronized with atomic time, but many cellphones don't display seconds by default.
      • See http://time.is if in doubt.
    • Elapsed time of the swim should also be noted, but should always derive from the difference between start time of day and finish time of day.
      • Reason: if only using elapsed time (i.e., stopwatch), what if you accidentally bump the stopwatch, or it runs out of batteries, etc.? If you didn't record the start time of day, you have a problem.
  • evmoevmo San FranciscoAdmin
    edited November 2017

    GPS coordinate formats

    When reporting coordinates of marathon swim routes and GPS tracks...

    Degrees + Minutes + Seconds (DMS)
    Degrees + Decimal Minutes (DDM)
    or Decimal Degrees (DD) ?

    Examples for my favorite swim spot, Promontory Point in the Hyde Park neighborhood of Chicago:

    • DMS: 41° 47' 43.4"N, 87° 34' 31.8"W
    • DDM: 41° 47.7236 N, 87° 34.5301 W
    • DD: 41.795393, -87.575501

    Decimal Degrees (DD) are most practical for computer applications (e.g., track.rs) - but please use at least 6 digits of precision, otherwise the stated location may not be what you think it is.

    And don't forget the negative/positive at the front. 41.795393, -87.575501 (Chicago) is much different than 41.795393, 87.575501 (northwest China) !

    For live observation purposes, Degrees/Minutes/Seconds (DMS) are probably most practical, because it minimizes writing.

    e.g., a given swim in Lake Michigan may take place entirely within the 41st degree North of latitude and the 87th degree West of longitude, so you can exclude the "41" and "87" for all but the first of the log entries.

    DMS, DDM, and DD can all be interchangeably converted... but whatever you do, please do not mix more than one of the three formats in the same log!!!

  • JaimieJaimie NYCCharter Member
    edited November 2017

    Great info, very helpful!

  • evmoevmo San FranciscoAdmin
    edited December 2017

    Q: What if I did a swim, but it's not documented to the standard of MSF Documented Swims? I had only a limited support team, and they didn't do an observer log or take any photos or get a GPS track. But, I still did the swim and would like it noted somewhere. What can I do?


    If you're claiming a first or a new record or Cuba-Florida or some other crazy route, then... bummer.

    Otherwise, consider filling out the MSF Minimal Swim Documentation Template. By itself, this wouldn't meet the standard for MSF Documented Swims, but it does a pretty good job of answering the basic questions about a swim (Who? What? Where? When?), and it provides enough detail for potential inclusion in the LongSwims database, or the future Wind, Waves, & Sunburn II.

    The minimal documentation template is also useful for corralling information about historical swims, which in my experience are far less likely to have real observer logs, GPS, or photo/video documentation.

  • evmoevmo San FranciscoAdmin
    edited January 2

    Q: What's the deal with GPS watches? Can I wear one on an official Documented Swim?


    In general, devices (worn by swimmer) that offer real-time direct feedback about pace or navigation are prohibited by (intentionally purist) MSF Rules.

    Technically, some currently-available GPS watch models do, in fact, have the capability of real-time feedback on pace and navigation. Therefore, they are disallowed by MSF Rules. Simple analogue watches (time of day) are specifically mentioned as standard equipment.

    Realistically, I doubt any marathon swimmer has gained a significant benefit -- to date -- from wearing a GPS watch. If anything, the bulk of current models (2017 or earlier) would contribute to performance-reducing drag on the wrist.

    But why should MSF be responsible for policing specific models of GPS devices, their respective capabilities, and whether swimmers are using them to their full potential (or future potential)? Seriously, we don't have time for that.

    Sarah Thomas and Chloe McCardel did world-record swims without wearing GPS devices directly on their bodies - why do you need them? Answer: you don't. Let your kayaker or boat pilot take care of it.

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