Grant Hutchison wrote:
The reason for this odd course isn't obvious in EarthA, but becomes
clear if you look at a map of Saint Martin / Sint Maarten, like the
one at http://www.netherlandsantilles.com/maps/stmarteen_map.jpg
the western end of the dry boundary turns SW and crosses a SW-facing
coast, propelling the equidistance line in that direction.

I find it incredibly difficult to find good maps of St.
Maarten/Martin. But the maps that I do find, sometimes have the
boundary turning point like on the map that you posted, but sometimes
they don't. An example of the latter is http://www.caribbean-on-
line.com/sm/smmap.shtml . I really don't know what is the truth here.
BTW, look also at the other dry boundary extremity, on the east coast
of the island. It looks like Oyster Pond is entirely enclosed by
Dutch territory.

I remember having seen a good 1:25000 French topo map of the island
once, but that is a long time ago. IGN will probably still have it on
sale. As for Dutch topo maps of the island: I haven't got a clue. The
Topografische Dienst advertises on its site only pre-1970 topomaps.
On-line: nothing.

I also found out that the Hydrographic Service of the Dutch Navy is
active in the mapping of the Dutch waters in the Antilles (together
with the neighbouring countries, it says). This was in 1999. The
similar service of the French navy is also currently involved in
this. It could be that they are still at it. So perhaps we will hear
the outcome in the near future.

Peter S.