How to win at sea battle

Sea battle looks like a guessing game and mostly is not. Two players of equal luck will not finish level, because almost every decision — where the ships go, which square to call, what to do after a hit — has a better answer and a worse one.

Here is what actually moves the odds.

Where to put your fleet

Stop hugging the edges. Everybody's first instinct is to line the border, and everybody's opponent knows it. The edge is also genuinely worse for you: a ship against the wall has fewer squares around it that need to stay clear, so it packs in tidily and leaves your interior suspiciously empty.

Do not leave a big empty middle. The no-touching rule means your ten ships claim far more than twenty squares — each one reserves its own ring too. If you crowd everything into two corners, the shape of what is left tells a careful opponent where to look.

Split the big ships up. The four-square battleship is the easiest thing on the board to find, because it cannot hide: a shot every four squares will eventually cross it. What you can control is what happens next. Put it far from your cruisers, so that the ring revealed when it sinks does not also clear the neighbourhood of something else.

Put the boats where nobody sweeps. The four single-square boats are the hardest ships to find and the last ones anybody looks for. Tuck them into the awkward gaps a methodical hunter leaves until the end — two squares in from a corner, or alone in the middle of an otherwise empty quarter.

Never place the same way twice against the same person. Nothing gives a game away faster than a habit.

Hunting: the parity trick

While any ship of two squares or more is still afloat, you never need to fire at more than half the board.

Colour the grid like a chessboard and fire only at the dark squares. Any ship two squares long or longer must cover at least one dark square, whichever way it lies — there is nowhere for it to hide between them. Fifty shots, not a hundred, to guarantee finding every ship that is not a single-square boat.

That is a genuine halving of the search, and it is the single biggest difference between a careless player and a decent one.

When the trick stops working

Parity fails on the boats. A one-square ship can sit happily on a light square and your entire chessboard sweep will pass straight over it.

So watch the sinking announcements. The moment the battleship, both cruisers and all three destroyers are down, the only things left are the four boats, and the parity rule no longer applies to anything. Switch to sweeping every remaining square.

Players who never make that switch lose games they had already won — they spend twenty shots re-checking a pattern that cannot contain what they are looking for.

After a hit

You have a hit and the turn is still yours. Do not wander off.

Fire next door. Try the four squares orthogonally adjacent — above, below, left, right. Never the diagonals: a ship cannot bend, and nothing can touch it corner to corner either.

Once you have two in a row, you know the direction. Stop probing sideways and work along the line. Fire at one end; if that misses, go to the other.

Count. You know what is still afloat. If three destroyers are already down and you have three hits in a row, the only thing that can be under your shots is a cruiser or the battleship — and if both cruisers are sunk too, it is the battleship, and there is exactly one more square to find.

Read the wrecks

Every ring that opens around a sunk ship is free information, and most players look at it once and forget it.

A wreck near the middle of the board clears eight to fourteen squares at a stroke. What is left is a smaller board — and the shape of the remaining empty space often rules out the battleship entirely from whole regions, because four squares in a row with clear margins simply will not fit there any more.

Before your next shot, glance at the biggest ship still afloat and ask where it could possibly be. Late in a game, that question often has only two or three answers.

The one thing that beats all of it

Because a hit earns another shot, the player who finds the first ship often never gives the turn back. Your opening shots matter more here than they would if every turn were a single shot.

So open on parity, in the middle third of the board, and away from wherever you opened last time.