Spedometer Help!

[22vdrive]

My supra has two spedometers and they don't agree with each other on how fast we are going! I think they are both off to be honest; is there any way I can get them to post a more accurate reading? How can I calibrate them? My boat is a 2004 22 SSV GG

[dusty2221]

You should have two knobs that look like the knob for a PAC 1 directly under the dash. You can adjust them to the correct speed while moving. I used the speedometer app on my iPhone to calibrate it. This app uses gps to calculate speed. It was also dead on with my perfect pass.

Take a look under the dash on the left of the steering wheel and see if you see something you can turn. Then just remember where it is when moving across the water!

[22vdrive]

Thanks for the tip, I'm downloading the spedometer app or my iPhone. I'll be calibrating next time I take it out!

[jzelt]

My knobs are on the right side (starboard) by the fill/drain buttons for the ballast tanks. I have a Garmin E-trex I took but you said you have an app.

I set both gauges to the same speed. Previous owner said you would set one for wake surfing and one for skiing for instance. Don't they read the same no matter how slow or how much weight you have?

Do you calibrate one for something and the other for another sport?