Richard Casady wrote:
On Fri, 4 Jul 2008 06:29:26 -0400, "Jim" wrote:

"Graham" wrote in message
news:ypjbk.54744$Jx.31786@pd7urf1no...
Does anyone know if these gauges display miles per gallon (or litres per
km) or just miles travelled and gallons consumed?

Do they need any special interface to work with standard GPS's like a
Raytheon chart plotter?

Thanks, Graham
The GPS reports miles per hour over land. It would be useless to use those
calculations in determining real miles per gallon over the surface of the
water.

It reports MPH everywhere equally well. It doesn't know sea from land
unless you get it wet. It reports speed over the land and if the land
is flooded, at sea or on a river, there may be an effect from
currents.

Casady


I keep my eye on the water, not on the gauges, unless I'm heading into
shallows, and then I watch out for diminishing depth. If I were
"voyaging" over more complicated waters than Chesapeake Bay, I'd pay
more attention to the electronics, I suppose, but I know the land sights
on both sides from Baltimore down to the mouth of the Potomac, so on a
reasonably clear day, I know where I am in space. This is no great
accomplishment...anyone who pays attention while out on the boat around
here can do the same.