sePL80: It looks like Sea Dogs: City of Abandoned Ships seems to be the most favorite iteration of this series amongst fans.
You can also check this forum for a link to an extensive mod to that game which seems to add lots of content (and eventually some gameplay-tweaks/bugfixes). This mod is still supported at the time of writing and seems to be updated regularily with additional content.
I still have to get my feet wet checking out this part of the series + the mod. (only just bought it during the current sale)
There has also been a "new" Sea Dogs release on steam as of lately, but it adds a lot of gameplay decisions which most Sea Dogs fans are probably not wishing for.
It was really too convoluted for my taste and added too much "Land RPG" to the game instead of concentrating on the "Sea RPG" part, cause that is where this series really shines in my opinion)
So I would strongly suggest getting your pirate paws on "Sea Dogs: City of Abandoned Ships" to get your Sea Dogs fix.
See you on the sea,
sePL
The forum link you are talking about doesn't seem to have posted. Perhaps this forum doesn't like external links. If that is the case I am thinking you are referring to Buccaneers Reef dot com. Just do a google search for Buccaneers Reef to find the extensive mod that you are talking about.