Which part of ship should be targeted while using guided artillery rounds?

Question

Situation, short:

• gun has similar firepower to 5 inch gun (5/62)
• most available rounds used are standard high explosives, there are a few armour piercing rounds available, rounds are guided and even around their maximum range have circular error probable of 10 m
• the target ships are being identified as 2 destroyer escort (~100m long) and 6 armed merchant (~150 m long)
• shells need ~45 seconds to reach their target, but can be reloaded in 6 seconds, so subsequent ones will be fired before any damage assessment is done

Which part of ships should be targeted while using guided artillery rounds? (Simple center of mass to have highest chance to hit? Around guns hoping they would explode? Try to score a hit near waterline? Around chimneys trying to get engine room? Ship bridge to get captain?)

Situation, long:

• on the other side, there is a small, semi-autonomous trimaran with a disproportionately big gun, classified as gun boat (a bit too slow to be considered as fast attack craft)
• under war conditions, when target is reasonably confirmed and human operators in HQ can not be reached the AI is allowed to open fire on its own
• there is a huge technological gap between both sides, but actually AI does not understand that. It is ordered to assume enemy quality of ships as "shoddy", but incorrectly assumes that it can be wiped out in any moment by torpedo or anti shipping missile.
• AI is NOT brilliant (a few versions earlier it was refereed as "Beached whale"). It's way of reasoning is highly simplified - meets with highly valuable enemy assets - unless is ordered to set some sophisticated trap by operators, should fire everything available at its targets. Simultaneously another algorithm should select where exactly to hit to cause the most damage. But such algorithm do not rely on sophisticated models, but mostly on reasonable rules of thumb - like try to hit anything but frontal armour of a tank or if enemy ship is listing to one side, then try to hit it more only from this side.

Answer 1

Given the parameters of your question, ("rules of thumb" and not being too smart), and assuming that this is about naval ships instead of space ships, the AI would select any hit below the waterline in nearly every case.

The most reliable way to end a battle with another ship is to sink it as quickly as possible. The most reliable way to sink a ship is to cause it to flood with water. The way to cause the most flooding possible is to hit the ship directly underneath the keel close to the center, such that a hole is created that allows water to go straight up into the ship as it is sinking. Hitting the keel is very difficult to do with guns, which is why this spot is typically targeted with torpedoes.

The next best thing to hitting directly below the keel is any place under the waterline. Any hit under the waterline will cause the ship to take on water. If the ship takes on enough water it will sink.

Finally, you ask about several alternative spots to target. Hitting a gun to make it explode may or may not make it reliably explode, but the explosion is not guaranteed to damage the ship enough to sink it. Hitting the engine room might kill everyone in the engine room and break the engine, which can cause the ship to stop, but it could still potentially shoot back at you and not sink. Shooting at the bridge to kill the Captain is a waste of effort; in a war situation the enemy will be prepared for this and will probably be able to assume control of the ship from a more secure location.

Shoot the waterline over and over until the ship sinks.