How to 'always' win at Battleship?

Battleship is a strategy type guessing game for two players. It is played on ruled grids on which each player's fleet of warships are marked. The locations of the fleets are concealed from the other player. Players alternate turns calling "shots" at the other player's ships, and the objective of the game is to destroy the opposing player's fleet. In this video you will learn the best strategy to win this game.

Chapters:
00:00 Rules
00:42 Strategy 1
01:11 Strategy 2
01:46 Strategy 3
02:22 Strategy 4

[dodothebirb]

Me calculating the entire probability map of a 10x10 grid while my friend is wondering why I took an entire hour to fire one shot:

[evanescentenquirer]

I think calculating the probability maps for each shot will take longer than actual naval conflicts

[iwersonsch]

An important caveat is that, if your strategy is known, your opponent can be adversarial about their ship positions. So if your strategy isn't random enough, your strategy might only be as good as the worst possible score rather than the average.

[Kallyn]

Another way to win is to move your ships around after each move and always claim the shot was a miss

[PeterZaitcev]

Fun fact. In Russia, there's a different variant of the ruleset. The only but major differences are:
1. After you hit (wound or destroy a ship), you can fire again immediately
2. There are no 5-cell ships, but instead each player has 4x 1-cell ships, totalling up to 4x1, 3x2, 2x3, 1x4
3. Ships cannot occupy adjacent cells, _even diagonally_

This changes the game pattern drastically and adds a good level of mindgames during the deployment phase.

[PaulMurrayCanberra]

A still better strategy is not to shoot where the ship most likely is, but to shoot whichever square gives you the most *information* about where the ships are. Once you have 100% information, then you can take out the ships.

[Electifried]

This video forgets a crucial part of the game: The part where you initially hide your ships. Where are the best and worst places to put the boats at? If you can work out the last place your opponent would think to guess, then you could have a huge advantage by sticking a boat there.

[sabinrawr]

One important caveat about the "hit and hunt" strategy: ships can be placed next to each other (this is different from the version more common in Eastern Europe). If the opponent has done this, your hunt may take longer than expected. You could easily have a string of 5 hits and sink nothing.

I'm not saying that hunting around a bit is a bad idea, but for completeness you may wish to account for this possibility when adding your probabilities.

[calebklingerman]

The problem with this strategy is assuming your opponent will place randomly. An opponent who knows about this may choose to place their ships around the edge. Unless they know that you know that they know, in which case they will cluster in the middle. Best to build up an immunity to iocaine powder beforehand, just to be safe.

[danik]

you don't need to hunt ships that you hit. you may instead count all possibilities for what you may have hit and where to continue, and either hit another square where you are likely to find something, or hunt the ship by choosing the spot where you are the most likely to continue sinking the ship. that may slightly lower the average time to sink the whole fleet.

[aaronbredon]

I shoot in the 4 long pattern first - that gives a 50% chance of a destroyer hit, and 75% for the sub and cruiser.
The 4 long pattern can be converted to the 2 long checkerboard after all found ships are sunk.

Being aware of what patterns can be converted helps a lot.

[spartacus]

We played a version where you didn't announce when your opponent had sunk a ship. This led to sneaky tactics like placing the cruiser and submarine end to end, and your enemy would stop shooting after 5 hits thinking it was the carrier, when really you still had the tail end of the submarine alive XDXDXD

Placing ships in a zig zag meant that they had no idea what was still alive to adjust their probability maps.

[JohnnyNumber]

In Germany, you can'r place ships next to each other (like shown at 4:02). So you will know, after sinking a ship, that all places connected to the ship (the diagonale onces also) aren't inhibited by an other ship.

[GregMoress]

I discovered you could stack all the ships on top of one another. The beauty is two-fold:
1) It's much harder to find the 5 spots.
2) After the sink the top ship they don't fire again at the same spots to sink the one beneath it... I'd be incredibly honest and admit a HIT if they did.

[musicalcharge]

Even if you don't calculate the exact probabilities every time, you can eyeball it all pretty quickly, which intuitively makes sense as well. Chances are higher in big open areas.

[bugfacedog]

I always just do the pattern where you search for any length-3 ships, and you have a 66% chance of hitting the little length-2 guy. Also there are times where I don't finish off ships after the first hit because you can waste shots finding direction, but would be clear exactly what direction it is if the grid is a little more filled out.

[yahnmahn]

I'm proud to say that I thought of the first three strategies all on my own while playing battleship. Unfortunately, I must be very unlucky, my sister always manages to beat me through random chance before I beat her.

[BrianStDenis-pjtq]

I wrote this game and used a similar scoring strategy. My score was based on the largest ship available, not the sum of the best shot over all ships remaining. The result is almost always a set of squares with the same high score, so the algorithm picks one of those randomly to shoot. But, humans can beat it because humans don't place ships evenly spaced. Also, the computer player needs a strategy for placing ships. My game uses random placement, which humans can hit fairly easily. The game side needs good ship placement and good shooting algorithm to beat a human.

[GGw]

my favorite strategy at this game is either : put ur ships in all corners or just stack'em as one big pile, just note that stacking them can confuse ur enemy at first because, when they shoot around they might find that one of ur boat have a "+"shape instead of a "-", but once they realise u just glued them all, u basically lost.
(also try playing shipwrecker with the wind waker noises, it makes it more fun, if u know what i mean)

[thierrypauwels]

The rules that I learned were a bit different. Each turn you had to announce 3 shots, and your opponent would only tell you the result of all three shots together, without saying which shot touched what. And the winner was not the one who sunk all the ships of the opponent, but the one who could locate all the ships of the opponent. A bit like mastermind.