We tried out the speed computer with the water wheel.
RPM and time could be read.

We investigated the modes and functions and way to connect.

Maximum revolutions per minute with the 40 tooth gear on the axle with
the water wheel went
240 RPM and could go to 300 RPM.

Changing the 24 tooth and the 40 tooth gear around the RPM was 140 and
could go to 180 at full force ( even 200).

We checked out the ratios to see if the numbers seemed reasonable.
 
 

For one more question to answer -
would the "paddle" float?

Yes, but only while there was still some air in or under it.