Speed recalibration after re-prop?

[svnfightsvn]

2007 vlx. I recently upgraded to a acme 1235 prop (was 537) and now it seems that my speed is way off. When I used to run 23mph or so, I now need to run at what is reading 27-28mph. Using a gps app on my phone, I can see that I'm really only doing the 23 like I was accustomed to. Has anyone had this happen? Is it because of the new prop with a lower pitch? Do I have to recalibrate my speedo? How do you go about doing that?

[mikeo]

Your speedo should be a paddlewheel (unless it's prefectpass) and reads from the movement of water and therefore there isn't any recalibration. The only 3 methods of boat speed I'm aware of are:

1. pitot tube
2. paddlewheel
3. GPS

None of these three methods have anything to do with the pitch of the prop or any engine parameter like the "old school" cable from the transmission in a car or newer wheel rotation sensors (piggybacked to ABS) where changing tire size required a recalibration of the speedometer. I don't have any troubleshooting ideas, but maybe I just need another cup of coffee. I'm interested to see what others suggest.

[svnfightsvn]

I'm talking about the perfect pass

[edwin]

http://perfectpass.com/sites/all/themes/perfectpass%20-%20Copy/images/wakeboardpro65manual.pdf

 

Section 6 CALIBRATING PERFECTPASS SPEEDOMETER (Wakeboard Mode)

If your digital speedometer is not accurate, you can go into the Speedo Cal screen of the system. This is accessed by pressing the DOWN key with the highlighted on the main Wakeboard screen.

 

Paddlewheel Factor SETPOINT

1. Calibration Adjust

We recommend you check and calibrate if necessary at 20 mph.

2. Menu Arrow

Speed Base Speed

 

With the Calibration Adjust highlighted on the screen press either the UP or DOWN keys to speed or slow the boat.

CASE 1. CASE 2.

Boat speedometer reading lower then PerfectPass Speedometer
Press the UP key until the boat speedometer matches the PerfectPass speedometer.
Boat speedometer reading higher then PerfectPass Speedometer
Press the DOWN key until the boat speedometer matches the PerfectPass speedometer.

 

When the speed readout matches the boat or reference speed press MENU once to highlight the then press the UP arrow to return to main screen.

Example: If you are set and engaged at 17 mph, but the analog speedometer or GPS is reading 18 mph, go into the Speedo Cal screen and press the DOWN key several times until the boat speed drops to 17 mph so the PerfectPass Digital Speedometer matches the GPS or boat’s speedometer.

Paddlewheel Factor – This value is the actual calibration value much like an RPM baseline. This number can be used to quickly determine where the calibration is at when troubleshooting the paddlewheel. This number is also very useful when trying to set calibration to match another system or to reset the calibration after a system RESET had been performed.