Faria Gauge Calibration

[MaineDR]

So I got the boat out yesterday to test the new gauges. I ran into a problem with the speedo. The new faria speedo was about 10 mph too fast compared to the perfect pass. Perfect pass is fairly accurate from what I can tell. The faria gauge came with a pot adjustment but even with that the correction seemed to fall out of the range of the adjustment to properly calibrate. Anyone had a problem with this before and know how to fix it?

[Fast351]

http://faria-instruments.com/site_manuals/IS0105H.pdf

1. Coarse adjustments may be necessary due to variations in
hull shape and mounting limitations. The coarse adjustment
is made by turning the six-position selector switch at the rear
of the case. Start with the switch in position 3 or 4. Increase
the setting if the speedometer reads high or decrease the
setting if the speedometer reads low.

2. Fine adjustments. Remove the weather seal plugs on the
rear of the speedometer located in the holes marked “ADJ”

3. With the boat at the known speed, carefully vary the
appropriate adjustment pot (through the hole in the case) with
tool provided (5/64” Allen wrench) until your Faria Marine
Instruments speedometer is in agreement with the boat’s
known speed. Turning the pot clockwise raises readings,
counter clockwise lowers readings.

I think the external pot replaces the internal one, but there is a coarse switch on the back of the gauge. You probably have to change that.

[MaineDR]

Thanks for the help. That sounds like an easy fix.