Its accurate enough to stand up in a court of law!

Bushnell has a low cost radar gun. We bought one for our speed shoot outs but have yet to try it out.

http://www.bushnell.com/products/digital/specs/10-1907.cfm

and what is wrong with getting the fastest instantaneous speed? That is what we are trying to get isn't it? Not an average over 500 metres which will be less.

Dave
http://www.westlakesailingclub.com