Sea Battle Strategy: Place and Hunt Smartly

The fleet

A carrier of five squares, a cruiser of four, a frigate and a submarine of three each, and a patrol boat of two: 17 ship squares in a sea of 100. Ships lie across or down and never overlap. Online, the server keeps both seas secret and sends each player only their own fleet and the shots they have fired; on one device, a curtain between turns hides each sea while the phone changes hands.

Placement: make the hunt expensive

A searching player finds ships by pattern and then finishes them by probing the neighbours of a hit. Placement should work against both:

• Do not touch. Ships placed next to each other let one hit lead straight to the next ship. Leave at least one square between ships.
• Use the edges and corners for some ships. Many searchers neglect the margins, and a ship along an edge has fewer neighbours to probe.
• Do not be predictable. All ships on edges is as readable as all ships in the middle. Mix.
• Break the chequerboard. The standard search hits every second square, which always finds ships of length two or more. You cannot defeat it, but a ship placed so that its squares alternate between "early" and "late" squares in a typical sweep delays discovery.
• Hide the patrol boat well. The two-square boat is the hardest to find and often decides the endgame. Put it where probes are unlikely: a corner or an isolated edge spot.

Auto-place gives a random legal layout, which is a fair default; a thoughtful hand placement is slightly better against the Hard robot.

Hunting: the chequerboard

Every ship covers at least two squares, so it covers at least one dark square and one light square of a chequerboard. Firing only at squares of one colour therefore finds every ship, with at most 50 shots instead of 100. Start in the middle of the sea, where more ship placements are possible, and work outward along the chequerboard.

Targeting: finishing a ship

When you hit, switch from hunting to targeting:

1. Fire at the four neighbours of the hit until you get a second hit.
2. With two hits in a line, fire along the line in both directions until the ship sinks.
3. When the game reports a ship sunk, return to hunting. If the hits do not add up to a sunk ship's length, two ships are adjacent; keep probing around the remaining hits.

Late game: think in probabilities

With few ships left and many misses on the board, the ships can only fit in certain places. Look for runs of unknown squares long enough to hold the remaining ships; a two-square boat can hide in many gaps, but the carrier needs five in a line. Fire at squares that lie in the most possible placements, which are usually in the middle of the longest unknown stretches. This is exactly what the Hard robot does, and it is why it finds the last ship quickly.

The robot levels

Easy fires at random. Normal hunts, then targets a hit until the ship sinks. Hard counts where the remaining ships can still fit and fires at the most likely squares, so against it the placement advice above matters: isolated ships and a well-hidden patrol boat cost it the most shots.

Common mistakes

1. Placing ships side by side. One hit finds two ships.
2. Hunting every square. Use the chequerboard; half the shots.
3. Leaving a hit unfinished. A found ship is the cheapest ship to sink.
4. Probing diagonally. Ships lie across or down; diagonal neighbours are never part of the same ship.
5. Forgetting the remaining lengths. If only the carrier is left, do not fire into gaps of four.

Glossary

• Hunt mode: searching for a ship with no current hit.
• Target mode: finishing a ship after a hit.
• Chequerboard search: firing at every second square so that no ship can hide.
• Sunk: every square of a ship has been hit; the game announces it.