Why does my boat seem slower than everyone elses?

i wakeboard behind 3 boats mainly.

1. My Mobius LSV

2. Friends Mastercraft X-10

3. Malibu wakesetter VLX

at the same length rope im at 21-22mph behind the mobius, 19mph behind the mastercraft, and 18.5mph behind the malibu.

the dealer told me that at 3K rpm my speedo's should read 30mph and they do, dead on, so is it the wake shape, speedo, or just boat??

Hull shape/weight will have more to do with wake shape at a given speed. What speed you ride at will depend on a number of variables.

Have you tried adjusting/tracking the speed using a slalom course? 20 MPH should take 28.97 seconds from start gate to end gate...

I don't think that 3k = 30mph thing is dead on with a V-drive. It was very close in my old Prostar, but my SSV seems geared a lot shorter.

Not all boats are exactly the same either. If you're doing the exact same RPM in all the boats, chances are they are definitely not going the exact same speed.

I personally prefer a calibrated speedo over the tach. Borrow a gps and check out all the boats.

Ditto Michah's suggestion. You can buy a handheld Garmin GPS unit for @ $100. When I want to verify my boat's speed I have the pitot speedo, a paddlewheel speedo for operation, and the handheld GPS for calibration.

And to add a note about calibrating...make sure you calibrate at the speed you're most concerned with. Indicated (speedo display) matches true (GPS) at only one speed in my boat: 24 mph. It lies under and over that speed. Not sure if a paddlewheel system would be any different.

A skier would calibrate at 30 mph or 3,000 rpm or whatever. A boarder might start there but then check at the speeds you're concerned with before shutting the jeeps down. I'd much rather have it right on at 22-24 than at 30.

Find a slalom course, it should take 16.2 seconds to go from the entrance gates to the exit gates (red boat bouys) at 36 mph, 17.2 @ 34, etc.