Vibration at 20/30 mph

[Spoleto13]

I own a 2003 26ft Chaparral with a 320 Volvo Penta GXI 5.7. This sunday took it for a spin and noticed that between 20/30 mph there a vibration through out the boat. What could this be? <br /><br />Thanks for your help.

 

[vinney]

Re: Vibration at 20/30 mph

Land and Sea torque shift prop. With bright cams.