"Lu Powell" wrote:

Are you sure you need an outside unit? Most modern outboards and I/O
drives have the speedometer sensor in the lower units. Look for a small
rubber tube at the front of the foot, check it for blockage or
disconnect.

Mine works fine on the mercruizer alpha1 on my boat but my
question is...........how accurate are they? Says my boat will
does wot 50mph and that was from brand new. Still does that with
2 years and 200 hours on it......

John
Searay 185br 2001