In the regular game, there are 18 locations where a settlement would touch only one hex (red dots), 12 locations where it would touch two hexes (yellow dots), and 24 where it would touch three hexes (green dots).
This is a ratio of 1.5:1:2.
In the 5-6 player expansion map, there are 22 locations where a settlement would touch only one hex (red dots), 16 locations where it would touch two hexes(yellow dots), and 42 where it would touch three hexes (green dots).
This is a ratio of 1.375:1:2.625. This new ratio is much more "open" with fewer 1-hex locations and more 3-hex locations. This open ratio allows players to build easily, without much interference from other players.
An alternate 5-6 player expansion map was created with 24 locations where a settlement would touch only one hex (red dots), 18 locations where it would touch two hexes (yellow dots), and 36 where it would touch three hexes (green dots).
This is a ratio of 1.33:1:2. This map forces the "tight" gameplay of the original map but is large enough to accomodate 6 players.
From your original game and 5-6 player expansion you will need:
Place the land tiles randomly following the pattern of 2,3,4,3,4,3,4,3,2 tiles per row. Randomly place a port at each end of each 3 tile row and place a port adjacent to each of the tiles in the 2 tile rows. Place a sea tile between each port. Your map should resemble the maps shown below (in the drawing, the dark blue triangles are the ports).
Randomly place the number tiles on the land hexes and play the game as normally.
There are two house rules we use with the alternate map that we think improve the game.