How to use a Garmin 305 to log heart rate data in the pool

It may be a little premature to do up a how-to before I’ve even fully tested to see if it works, but I’m a little excited to try this out. I don’t feel like spending another $200 for another watch so I can track heart rate underwater, especially when I don’t know if I’m going to even find it practical or useful to have that data yet. So back to the spare parts bin to try to hack together something that will work.

My first attempt was to just wear the heart rate strap in the tub, and having the GPS unit close to it. Reception was spotty. There didn’t even seem to be any rhyme or reason to why it would or wouldn’t pick up a signal. Sometimes it could be right next to it and not work, and sometimes if it was far away it’d get a signal. I decided that I’d probably have to keep them close to each other, or at least have no water between them. So I figured out another way to sort it out.

I started with a basic original style Garmin heart rate strap.


…and an underwater camera bag.


First I applied a thick bead of silicone around the main part of the strap.



…then just stuck the underwater bag onto the strap and let it dry.


It doesn’t even look awkward at all!


Here’s the GPS in action, obviously getting a reading (I was out of the water).


Next I tested it in the tub, and it definitely got a solid signal the whole time. Sorry, no pictures, but I DO have a chart showing no dropouts during the five minute impromptu bath I took!


Monday I’ll be testing this, so I’ll be sure to update this post. Hopefully I don’t get laughed out of the swim session!