A good while back I posted about an idea of having a audio speedo which beeps more  frequently the faster you go. Anyway didn’t come to much but with the current restrictions and sailing but not racing I have revisited. 

There are more details below but basically it is a piezo buzzer, battery  and a reed switch all driven off an impeller.

Tested it today and will it simply works and is a responsive indicator of speed for all aspects of sailing. Probably of little use to hot shorts but as a middle of the fleet sailor I’m hoping until will can get back to racing will help my restricted sailing. Yes I know I can’t use it for racing 

https://tinkboats.com/2021/01/03/sail-training-audio-speedo/" rel="nofollow - https://tinkboats.com/2021/01/03/sail-training-audio-speedo/

Thanks. Yes the silver cylinder is the magnet. Happened to have a nice strong one. I would say that less than two knots it stopped, to be honest I didn’t expect it to work as well as it did and had planned to add an extra set of blades for the low speed but didn’t need to. 

When the boat goes fast the impeller is very much surface piercing and when she accelerated the prop jumped out of the water. My stream testing had the impeller sinking too much  so I added adjust corks to control the depth. Now going to add weight.