Free Tile Mapping App, Dungeon Crafter tiles fit it.

[gameleaper]

one more tip, is you can put the map back into the program for editing ontop, you place the finished map back into the user folder and that then will be the default backdrop, board.bmp

if you have a border like I have used , you can put the border file in the user folder for it to be the default backdrop board.bmp

, so if you don't change the position of the Ship from top left, you can keep putting it back into the user folder named board.bmp and keep re-editing it. but it has to be a bmp I use MSPaint for changing from png to bmp etc...

[gameleaper]

one more tip, if you use the cursor keys to scroll around the Map your editing, it can be a big map, so all your ships can be on one Map file, just don't past ships manualy with an art program because they wont to aligned to the grid, you can then keep plugging it back into the user folder for rediting. you get 2048x2048 pixel map to work with.