We will be using them to measure water currents past our jetty due to
passing shipping.

Steve Lusardi wrote:
I am very curious why you ask. This system has been out of production
for a long time now. I too am a fond user, so I am also concerned about
the availability of spares to keep it running.

They are an old design, but we've just bought two so they are still
available.

I hope you realize that it is designed to produce
the same pulse train rate of the conventional impeller, as the
electronics beyond the speed box are interchangeable. So it shouldn't be
rocket science, once the impeller pitch is measured.

We don't have a conventional impeller to measure, and I can't find info
regarding its ppnm rate anywhere either.

Sperry Marine make a much more
sophisticated version for ships. That system measures flow in both the x
and y direction and can have multiple sensors on the hull. Its purpose
is primarily used to measure water currents when inshore.

Hmmm. Pity I didn't know about that earlier. Too late - I must use what
I've got.

Thanks for your comments.