[Freegis-list] Which OS GIS package to edit/query shapefiles?

[Brent Wood]

I have a coastline as a shapefile.

I want to draw lines across various bays.estuaries & harbours to determine
their areas.


Is there an OS GIS tool that will let me graphically interact with the data,
draw lines with the mouse, merge these lines with existing lines/polygons and
define the new polygons to derive the areas?

I can see a way of using PostGIS by gridding the regions with small cells &
running a query to sum the areas of the cells outside the coast &
left/right/below/above certain locations but this is a very cumbersome
approach, & is very non-graphical/interactive.

I can't seem to do this with JUMP, in that I close a bay by moving one vertex,
but can't get a clean topology with a new area (the bay) out of it.

This is frustrating as the operation is trivial with my commercial GIS package,
which I'm trying to replace with OS GIS software.


Any advice/help appreciated. 

Brent Wood