How to Play Battleship Solitaire: Rules, Fleet and First Moves
Battleship solitaire (Ships) for beginners: the rules, the fleet, the no-touching rule, revealed pieces and a full 6x6 puzzle solved step by step.
Battleship solitaire is a one-player logic puzzle. A fleet of ships is hidden in a square grid, and the number beside each row and column tells you how many of that line's squares hold a part of a ship. Ships are straight lines of squares, placed horizontally or vertically, and no two ships touch, not even at a corner. You use the numbers, the fleet list and the no-touching rule to find every ship, without guessing. This guide is for complete beginners.
The puzzle was invented in Argentina in 1982 and borrows its theme from the two-player guessing game (Conceptis: Battleships history). If you want to know how the two compare, read Battleship the game vs. Battleship the puzzle. Here we stay with the puzzle: the rules, what the numbers mean, and a complete small grid solved one move at a time.
The rules of Battleship solitaire
Battleship solitaire has four rules, and every deduction in the puzzle comes from one of them:
- The fleet is fixed. You are told in advance exactly which ships are hidden: how many, and how long each one is.
- Ships are straight. Each ship fills a line of squares next to each other, horizontally or vertically. Ships never bend and never run diagonally.
- Ships never touch. No square of one ship is next to a square of another ship, not sideways, not above or below, and not diagonally. Every ship is surrounded by water or by the edge of the grid.
- The numbers are exact. The number beside a row (or under a column) is the number of ship squares in that line. Not at least, not at most: exactly.
Every square that is not part of a ship is water. Solving means deciding, for every square, whether it is ship or water. A ship may lie along the edge of the grid or in a corner; the edge is not a ship, so it does not count as touching.
In Puzzle Picnic the game is called Ships. You tap a square to cycle between water and ship, or drag to paint several squares at once, and a fleet legend shows every ship you still have to find.
Reading the row and column numbers
The row and column numbers in Battleship solitaire are the main clues in every puzzle, and the most useful thing about them is that they are exact. Three readings come up again and again:
- A 0 means the whole line is water. Mark every square in it at once. Zero lines are the best place to start any puzzle.
- A line that has its number already is finished. If a row's number is 2 and you have found two ship squares in it, every other square in that row is water.
- A line whose open squares match its number is all ship. If a column's number is 4 and only four squares in it are not yet known to be water, all four are ship squares.
The numbers also add up. The row numbers and the column numbers each total the number of ship squares in the whole fleet. That gives you a quick check on a printed puzzle, and later it helps with counting ("this half of the grid still needs five ship squares").
The fleet: what you are looking for
The fleet in Battleship solitaire is always given, and in the classic 10x10 puzzle it is ten ships: one battleship of four squares, two cruisers of three, three destroyers of two and four submarines of one square (Conceptis: Battleships rules). That is 20 ship squares in a grid of 100, so four squares in five are water.
Smaller grids use smaller fleets. Ships has four levels, and the fleet grows with the grid:
| Level | Grid | Ships | Ship squares |
|---|---|---|---|
| Easy | 6x6 | 6: three of 1, two of 2, one of 3 | 10 of 36 |
| Medium | 8x8 | 8: three of 1, two of 2, two of 3, one of 4 | 17 of 64 |
| Hard | 9x9 | 9: three of 1, three of 2, two of 3, one of 4 | 19 of 81 |
| Expert | 10x10 | 10: four of 1, three of 2, two of 3, one of 4 | 20 of 100 |
The fleet is a clue in its own right. If you have already found the only four-square ship, a straight run of four open squares cannot be another one. If both two-square ships are placed, any ship you find next must be a submarine or a three. Keep half an eye on the legend as you solve; the strategy guide calls this fleet accounting.
Ships never touch, not even diagonally
The no-touching rule in Battleship solitaire means that every ship comes with a ring of water around it. Once you have found a whole ship, you can mark that ring straight away, which often finishes several rows and columns at once.
You do not even need the whole ship. A single ship square tells you something about its corners: because ships are straight, a square diagonally next to it can never belong to the same ship, and a different ship there would touch at a corner. So the four diagonal neighbours of any ship square are always water.
This "corners are water" habit is one of the most useful reflexes in the game. There is a whole post on it: why ships never touch, and how to use it.
Revealed squares and ship pieces
Many Battleship solitaire puzzles reveal a few squares at the start, either as water or as a piece of a ship. In printed puzzles the shape of a revealed piece tells you which part of a ship it is (Conceptis: Battleships rules):
| Revealed piece | What it is | What it tells you |
|---|---|---|
| Water | No ship here | One more square ruled out |
| Round piece | A whole submarine | All eight squares around it are water |
| Rounded on one side | The end of a longer ship | The ship continues on the flat side; the other three sides are water |
| Square piece | The middle of a ship of three or more | The ship continues on both sides, either across or up and down |
A middle piece against the edge of the grid is a gift: the ship cannot continue off the grid, so it must run along the edge. In Ships, Easy puzzles reveal a few squares to start. For more on what each piece forces, read reading ship pieces.
A first puzzle, solved move by move
Here is a complete Battleship solitaire puzzle on the Easy grid: 6x6, with the Easy fleet of one three-square ship, two two-square ships and three submarines. It reveals no squares, so everything comes from the numbers. Columns are A to F from the left, rows 1 to 6 from the top.
Move 1: the zero lines
Row 3, row 5 and column D all have the number 0, so every square in them is water. That is 16 of the 36 squares done before any thinking.
Move 2: column B needs everything that is left
Column B has the number 4. With rows 3 and 5 now water, column B has exactly four open squares left: B1, B2, B4 and B6. Four needed, four open, so all four are ship squares.
Move 3: B1 and B2 make a whole ship
B1 and B2 are ship squares next to each other, so they belong to the same ship, which runs up and down. Above B1 is the edge, and below B2 is water (row 3). So this ship is exactly two squares long: one of the two destroyers, complete. Its neighbours A1, C1, A2 and C2 are water.
Move 4: row 1 and the second two-square ship
Row 1 needs 3 ship squares. It has B1, and A1, C1 and D1 are water, so the only open squares are E1 and F1. It needs two more and has two open: both are ship. E1 and F1 sit side by side between a water square (D1) and the edge, so they form the second two-square ship. The squares under them, E2 and F2, are water. Row 2 needed only 1, and B2 already gives it that, so row 2 is finished.
Move 5: columns F and E
Column F needs only 1, and F1 is it, so F4 and F6 are water. Column E needs 3. It has E1; E2, E3 and E5 are water; that leaves E4 and E6 as the only open squares, and the column needs exactly two more. Both are ship.
Move 6: row 4 holds the three-square ship
Row 4 needs 4. It has B4 and E4, and D4 and F4 are water, so the two open squares A4 and C4 must both be ship. A4, B4 and C4 now form a straight run between the edge and the water at D4: that is the three-square ship. E4 has water on all four sides (D4, F4, E3, E5), so it is a submarine.
Move 7: the last row
Row 6 needs 2, and it has B6 and E6. Everything else in row 6 is water. B6 and E6 each have water all round, so they are the last two submarines. Check the fleet: one three (A4 to C4), two twos (B1 to B2, E1 to F1) and three submarines (E4, B6, E6). Every row and column matches its number. Solved.
Notice what you did not need: no guessing, and no trying a ship somewhere to see if it fits. Each move followed from the rules and the numbers. A puzzle with exactly one solution can always be solved this way.
Habits that make the first puzzles easier
A few habits make Battleship solitaire much calmer, especially on your first grids:
- Mark water, not just ships. Beginners often only mark ship squares. But four squares in five are water, and every water square you mark makes the "open squares" count in its row and column smaller. Most moves in the puzzle above came from water.
- Look at the lines with the biggest and smallest numbers first. Zeros are free. Big numbers, like the 4 in column B, often leave no choice.
- Draw the ring as soon as a ship is closed. When a ship has water or the edge at both ends, it is finished, and all its neighbours are water.
- Mark the corners of every ship square. Even when you do not know which way a ship runs, its diagonal squares are water.
- Recount after each ship. After you place a ship, check which rows and columns it finished. One ship often completes two or three lines.
When you get stuck, go round the grid once more asking the same two questions of every row and column: how many does it still need, and how many squares are still open? If that does not help, look at the fleet: where can the biggest ship still go? That question is the start of the next level of technique, covered in Battleship solitaire strategy.
Frequently asked questions
Is Battleship solitaire the same as the board game Battleship?
No. The board game is for two players who take turns guessing where the other has hidden their ships, so luck plays a part. Battleship solitaire is a logic puzzle for one person: the row and column numbers give you all the information you need, and a good puzzle has only one answer.
Can ships touch the edge of the grid?
Yes. Ships may lie along the edge or sit in a corner. The no-touching rule is only about other ships: no two ships may be next to each other in any direction, including diagonally.
Do I ever need to guess?
Not in a well-made puzzle. If a puzzle has exactly one solution, there is always a next step you can prove from the rules and the numbers. Every Puzzle Picnic puzzle is checked by a solver to have exactly one solution, and logic gets you there.
How big is a Battleship solitaire puzzle?
The classic printed puzzle is 10x10 with ten ships. Smaller grids are common for beginners. In Ships, Easy is 6x6 with six ships, Medium 8x8, Hard 9x9 and Expert the classic 10x10 fleet.
What is the best first move?
Mark every row and column with a 0 as water. Then look for a line where the number of open squares equals the number it still needs, and fill those squares with ship.
Where to go next
Once a 6x6 grid feels comfortable, the bigger levels add a four-square ship and more ships in all, so you lean more on the fleet. The strategy guide walks through a full 8x8 puzzle with the techniques that bigger grids need, and the Ships topic page collects everything else, including the story of the puzzle's many names.
To practise, the Ships page on Puzzle Picnic has the rules and a Play button. There is also one daily puzzle a day, the same for everyone; it rotates through the six games, so every sixth day it is a Medium Ships grid.