[This is a repost from our archives with new notes at the top (original post here): This rough Battleship Sudoku is a bit of a mind twister, at least until you carefully consider both how the fleet gets placed and what is special about the values across the boats. It is a quintessential example of the Battleship Sudoku that were in my first (and long since out-of-print) book that I might republish someday.]

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between number placement, ship placement, and shading modes. The shading mode in gray, which numbers can be written on top of, may work better than default ship placement.)

Theme: Twister

Rules: Standard Battleship Sudoku rules.

Estimated Difficulty*: 4 stars

Time Standards (highlight to view): Grandmaster = 5:45, Master = 10:30, Expert = 21:00

Solution: PDF