Beach sand is formed by erosive processes in the oceans; water takes millions of years to break up rocks and shells, forming particles between 0.063 mm and 2 mm in size. Its composition can be silicates (minerals with quartz), carbonates of inorganic origin or biogenic fragments (CaCO3 such as limestone), volcanic rocks…

These compositions are usually non-conductive to electricity. A priori, we might think that, because of this, sand will not affect timing. But nothing could be further from the truth.

Pure water, H2O, does not conduct electricity. But as soon as salts are added, it becomes conductive. Therefore, we can say that sea water is conductive without entering into what specific conductivity it has. Therefore, wet beach sand has a certain conductivity.

If we have wet sand on top of our timing antennas, not only are we not going to detect readings well, but we may even screw up the RFID reader because a lot of the energy it emits is going to come back to it because it is not transmitted.

On the other hand, although dry sand is not conductive, it affects tag reading as well as other non-conductive materials. In fact, it has a big impact.

We have carried out an experiment on the beach of several cases that can occur in any triathlon or open water race and we have grouped and ordered them from greater to lesser incidence in the tag readings. We have taken the timingsense antennas as a reference. Other timing systems will also be affected, especially by the sand on top of the timing point, but will be affected in a different way.

• In green, the options that virtually do not affect the reading and performance of the timing system.
• In yellow, the options that have an impact but would allow timing, even if you would need to check for possible loss of tag readings.
• In red, the options that make it impossible to time a race.

Remember that theser are ordered according to how much they affect readings, from more to less.

Our conclusions

Wet sand affects readings more than dry sand, but even dry sand can prevent good timing. Where it has a bigger impact is when it is at the top. This is logical because the antennas used in timing based on UHF technology usually have a ground plane at the bottom so that it does not affect the composition of the ground so much.

Those of you who have used low or high frequency timing systems in the near field know what I am talking about and how a bad ground affects. I already talked about this in a previous post.

La arena húmeda afecta más que la seca pero incluso la seca puede impedir la buena práctica del cronometraje. Donde más afecta, es en la parte superior. Esto es lógico porque las antenas que se usan en el cronometraje basadas en tecnología UHF suelen tener un plano de masa en la parte más inferior para que no afecte tanto la composición del suelo. Los que habéis usado sistemas de cronometraje de baja o alta frecuencia en campo cercano, sabéis de lo que hablo y lo que afecta un mal suelo. Ya hable de esto en un anterior post.

Therefore, our recommendation is that if you are going to time on sand, use side antennas like the ones we sell with the Triathlon Pack or bring a good broom. 🙂