Newbie here. If I should be somewhere else, please let me know.

A couple years ago, I bought a pontoon boat. We chug around our lake
with it, and love it. I would like to add a speedometer. I've searched
around, and most boat speedometers cover a range of 0-60 mph, 0-70 mph,
or even 0-80 mph. It is the NASCAR syndrome. This is completely useless
on a pontoon boat, of course, since top speed is 15-16 mph. So I'm
looking for a speedometer that covers 0-15 mph or 0-20 mph. Slow speed,
in other words. Best I've found so far is a unit that covers 0-35 mph,
but the scale is non-linear, and 15 mph is way down at the bottom of the
scale.

Can anyone point me to a slow-speed speedometer, or a manufacturer or
distributor thereof?

Thanks in advance.

Bill