We got this question from a reader
Hello, I am currently doing a school assessment about the technology of rowing and I was wondering how the impeller is able to get the reading of splits/watts. What technology is used to measure/detect the speed?
The impeller has a magnet inside it and as it spins, the magnet passes over a corresponding magnet mounted inside the boat on the base of the hull (usually in your foot well) and this has a wire connecting it to both the under-seat magnet (for stroke rate) and the box that reads, interprets and displays the data.
The faster the impeller spins, the greater the speed of the boat. BUT you have to calibrate it first.
I’ve not seen an impeller that reads watts – most do boat speed in 500m splits or meters per second. From this the box unit can interpret through to distance travelled. Watts is a measure of power.
Anyone want to add to this?