Brian,
I think I know what the Captain's license means (can do charters, etc), but can you give us "land lovers" more details? 

Ride S
Fired00d

Gary I couldn't find a web site that gave detailed information on what the Captains license means
I received my OUPV license with an endorsement to tow. This allows me to be hired by up to 6 individuals in Inland waters ie; bays rivers, sounds,etc in the U.S.A. and up to 100 miles offshore . This opens up the Bahamas and when things change, also Cuba. This can be done in a vessel up to 100 tons of displacement.
You have to be a US citizen, be 18 years old, 360 days on the watersince your 15th birthday, not convicted of any felonies, and speak English to qualify to take the test.
My next step is to upgrade to 200 tons in an inspected vessel, If the Coast Guard allows some of my sea time, that was not allowed when I took my test, I should have enough sea time to accomplish that. That was wrong in saying it was not allowed....I had a boat that I had over 800 documented days on the water and for some reason the Dept of Wildlife in NC can see where I bought the boat, sold the boat, but can't see where I registered the boat....since this mix up occured my time on that boat is being held for 12 months for me to get it strait with the Dept of Wildlife......