It's accessable in 2nd. Flotte rather quickly at the beginning of the game.

If you have SH3 Commander, you can make it your default boat.

I've got SH3 Gen (love the intel reports lol), Harbor Traffic 1.47 (or whatever the latest version is), and...Chung's Improved Orders (I think that's what it's called, could be wrong).

EDIT: Got MapMarker v1.1 too. :D