boat speed

[LostSailor]

Now that I got the boat up and running again I noticed she isnt quite what she used to be.

At 5000RPM she only goes 40-41 mph. She used to get 51.

Would a unwaxed hull and prop dings drag it down that much or is just a function of the 12 year old motor?

Thanks

[Bob H.]

What are you using to measure speed? Are you sure the tach is accurate? Wax will actually slow you down, but not 10mph and the hull stays cleaner. Prop "dings" shouldn't drop speed significantly either. There's a ton of variables. Check compression lately? Same weight and fuel? Same water conditions? Tachs and speedo's are notorious for being inaccurate as they age.

[LostSailor]

im chalking it up to what the speedo read 10 yrs ago to my GPS today....

[gary49]

Yep, that's probably what the problem is, Pitot speedometer is really not very useful. If your RPM is the same at WOT, then you're going the same speed as before.