May I suggest the following addendum to the .map file? It ensures a reasonable spacing of start positions.
I can also make the neighbours of these start sites site-rich and large, if you wish to use such a change.
Code:
-perl -f BalancedWater.pl 4 3 < "Boiling the Ocean.map"
#start 374
#start 22
#start 35
#start 165
#start 137
#start 88
#start 239
-- sea start
#start 205
#start 122
#start 245
#start 23
#start 57
#start 190
#start 98
#start 142
#start 252
#start 288
#start 53
#start 286
-- sea start
#start 304
#start 340
#start 369
#start 346
#start 334
#start 355
-- found 25 start sites.
-- 269 is isolated from 25 start positions.