voltage regulator
 

Thank you to everyone who responded. The problem was solved, when as a last
resort before removing the alternator, I checked the connections between the
alt . and the battery switch. I found a small amount of corrosion at the
switch, I really didn't believe this could be the problem, but I cleaned it,
reconnected, and took the boat for a test. The charging system worked as it
should, I have no idea why, this simple fix cured my problem, but the truth
is...who cares, couple of hours labor, $200 bucks, 60 mile roundtrip saved.
Thanks again.
John