As others have mentioned, get a GPS and forget it. There is no way to
adjust without taking it apart and bending the expansion tube in the back.
This will make it read correct on top end but not at other speeds.
I highly recommend the Garmin emap. Easy to use. Great for in the car as
it has full maps and info on what is at every exit on the Interstate. Also
shows you where the rest areas are at. Has full map of most all lakes and
rivers. Don't worry about the memory card and extra maps. You probably
will never use them. Just get the base unit and a cig adapter cord.
You will also now know exactly how far you have traveled and know exactly
how far you can travel for a full tank of fuel.
Check ebay for a decent price. Should be able to pick one up for $100 to
$125.
I don't recommend saving the money and getting one without maps. You will
love the map feature once you use it.

--
Tony
my boats at http://t.thomas.home.mchsi.com



"Kirk Davison" wrote in message
news:kO5cc.190432$po.1008776@attbi_s52...
Is there an easy way to adjust a speedometer on a 1982 Bayliner 1950
Capri,
It shows my top speed at 35 but a radar gun is showing 42. I have a 125
Volvo IO. This is a putt around the lake boat and being an old boat there
are a lot of things I would rather put money into than this but if there
is
an easy adjustment that would be great.
Kirk