i got out on the water today with a gps and calibrated my Perfect Pass and Stock Dash Speedo. Did this in a Small Stagnate area with no current, and I ran both directions.
I found my Perfect Pass and the Dash unit to be reading 3 mph low of actual @ 25mph PP set point. I adjusted the dash unit and PP to match the GPS. Then I decided to test and see if the variation was linear. (Basically, Will it still read correctly at 40mph.) At 40mph, the PP was dead on, however, the dash was reading 2mph low of actual. I adjusted the dash unit up to read correctly at 40mph. Dropping back down to 25mph, the dash unit reads 2 mph fast.
To sum, The PP reads correctly. However, the Dash unit doesn't follow a linear scale, I can calibrate it at 40mph, but it'll be off for slower speeds or I can calibrate it at 25mph, and it'll be off for high speeds.
Anyone else experienced this?
This is in an 04 Malibu Wakesetter, with a perfect pass that I added using the existing paddle wheel.