Under Construction

Photo by Plymography
Photo by Plymography

As a rather mediocre but dedicated swimmer in a country with cold winters I spend quite some time every other day swimming laps in a pool. But because of the meditative nature of swimming, it’s often quite hard to keep track of your lap count (at times I even struggle to remember breathing). Still, although you’re not some sort of an athlete it would be nice to know roughly how many laps you did in a session.

My other passion is software engineering. Even in the water I often can’t stop thinking about programming problems. Due to the lack of most audiovisual sensory input, being submerged is actually great for breading ideas. One such idea is the project this blog is all about: Rfish – a system to count swimming laps.

While I got a vague vision of how to build such a system, the work is far from done. In fact, the minimal main site and this blog are all there is for the moment. Rather than building the system behind closed doors I’ll try to share every single step it takes to build it – from registering the domain name to the engineering of the system and implementing a first prototype.

Of course, such an approach could end in utter humiliation. But on the other hand there is a fair chance that this project can profit from your input and comments and become useful to more than a single person. Still, I’m scared. I never took part in one, but this must be the web equivalent of hearing the start signal to the first lap of a swimming contest.



6 Responses to “Under Construction”

  1. CrispyChris Says:

    This looks like a really top project. As a regular senior swimmer and would-be geek, logging metres etc would be fun. I swim with a regular club and I’m sure the coach would be interested in it for the top swimmers
    Two observations
    1) What is the range of sensing in water considering tumble turns (so distance might be one metre)

    2) Could you log lap times as well?- could be used for interval training, maintaining consistent lap times during sprint sets and so on.

    I think this project has legs (haha)(fins?)

    UK based senior swimmer

  2. tamberg Says:

    Thanks! The range of the current prototype is very low (a few centimeters). A bigger antenna would help, but use too much battery or a dangerous (?) power supply. Logging lap times is possible and with the current design it’s accurate to a second. There’s still work to be done on the user interface though. Regards, tamberg

  3. LuckyLou Says:

    Wonder if there has been any progress on this since 2009? I have been wondering about something like this for a while and as i was swimming tonight I thought about RFID and /or Bluetooth so I Googled and found your site tonight.

    Recently bought the Zephyr Bluetooth heart rate monitor and mate it to my DROID X for biking using the SportTracksLive software and would love to log my swimming also.

  4. tamberg Says:

    Hi LuckyLou,

    After finishing the reader hardware, I wrote the Web server in an easy to understand way, using a free and dead simple server-side Javascript solution called AppJet. Unfortunately, AppJet closed shop shortly after. Since then, numerous other side projects prevented any further investigation of the topic.

    If you want to build the reader, there’s a step by step Intructable at

    But maybe in your case it would make more sense to wear the heart rate monitor while swimming and use the Bluetooth signal strength to count laps.


  5. Phil Robertson Says:

    did this ever happen? Can I buy an rFISH?

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