When I bought my first yacht in the late 70s I fitted it with a log which
used the doppler effect to
measure boat speed. Can't remember the make.
The sensors (one each side) were glassed onto the inside of the grp hull
and as I remember it was
accurate and worked perfectly.
There was never any need to remove and clean a fouled impeller.
It's still possible to buy these for commercial vessels (mains powered,
large power consumption etc)
but does anyone know if such instruments are currently available for small
craft?
Brian
