When ramming an enemy ship, a certain amount of damage is inflicted to the hit point pools of both ships. If a ship receives damage that exceeds 10% of its total hit points, it will begin flooding. Factors which affect the amount of damage inflicted by ramming are: a ship's speed (relative to the other ship), its mass and the size of its hit point pool.
Speed is the factor which determines the level of damage inflicted to another ship. To ensure the maximum amount of damage is caused to an enemy ship, collisions must be achieved at the highest speed possible. High-speed collisions immediately inflict a high level of damage to both involved ships. These types of collisions typically result in the destruction of one or both of the involved ships. In contrast, Low-speed collisions do not inflict a high level of damage. Instead, a lowered amount of damage is inflicted to both ships during the time they contact each other. The amount of damage is dependent on the speed of impact. This type of collision is not common because it only occurs when the combined collision speed is very low, between 0 and 5 knots.
Size Of Hit Point Pool
Damage from a collision is not determined by a ship's current hit points (HP). Rather, a ship's total HP pool determines the maximum amount of damage that it can inflict to an enemy ship. In a high-speed collision, a ship with a large HP pool has the potential to inflict heavy damage. Ships with small HP pools, such as destroyers, have a reduced maximum damage output in a collision.
For example, Yamato has 97,200 HP. Since ramming damage is determined by the total HP pool, Yamato is capable of inflicting 97,200 damage through ramming. If a Yamato with 5,000 HP remaining were to ram an enemy Yamato with 97,200 HP, both ships would be destroyed. This is because the maximum damage output during a collision is determined by the total HP pool of ships, rather than the current HP in a battle.
It seems that the ramming damage caused by a ship is roughly proportional to its mass and to the square of the relative speed (see Kinetic energy), except that the highest possible damage is the ship's total HP pool.
Flags And Achievements
If a player rams an enemy ship during a battle and survives, that player will be awarded a Die Hard achievement.
Hotel Yankee signal flags are rewarded for earning a Die Hard achievement, and provide the following effects:
- -20% to damage received when ramming the enemy.
- +50% to damage dealt when ramming the enemy.
Deciding To Ram
The first question is whether to ram at all. Since it is not trivial to pull of a ram, and even a successful ram typically results in the destruction of both ships, you must consider carefully whether this is better than the alternatives. Consider the following factors:
- What would be the effects of a successful ram? For example, ramming a battleship with a destroyer is rarely worth it, since it will certainly sink the destroyer but might not sink the battleship.
- How likely are you to pull off the ram? If you cannot survive long enough to ram, it is not a good idea to try.
- How likely is the target to die without you ramming them? If the local situation already favors your side, it is probably not worth throwing your ship away.
- How much health do you have, and how much health does your target have? If you are at low health and your target is at high health, it is a more favorable trade than the reverse.
Some factors influencing the chances of a successful ram:
- Proximity. The closer you are, the less chance the enemy has to notice and sink you or get out of the way.
- Facing. Most successful rams are head-on, or at least start that way, since this provides the highest rate of closure and the fewest options for the target to avoid your attempt.
- Speed and maneuverability. An advantage here means you reach your target quicker and makes it harder for the target to dodge. However, note that destroyers and cruisers, while generally faster and more maneuverable, are less likely to trade advantageously even if they do pull off the ram.
- Health. High health makes it less likely to be sunk before ramming. However, high health also makes the ram a worse trade.
- Local tactical situation. If there are many enemy ships with good shots on you, it is less likely you will be able to survive to ram successfully, especially given that the approach often will put you in an increasingly vulnerable position. Unfortunately, as with health, a good local tactical situation generally makes the ram a worse trade.
- Torpedoes. Attempting to ram a target that has torpedoes is very dangerous, since attempting a ram will put you in a perfect position for them to hit you with them.
During The Attempt
- If you judge the ram is likely to succeed, you may want to shoot enemies other than your ram target, given that both of you will likely be destroyed in the ram. Make sure you don't get too distracted and miss your ram though!
- On the other hand, if the ram is unlikely to succeed, or the ram target is a ship you simply must eliminate, you can shoot them for a little extra insurance. If you are lucky you might sink them first and not have to give up your ship in the ram.
- If your ram target notices your attempt too late, they may attempt to turn around. This is a good opportunity to shoot them in the citadel.
- Sinking enemy ships or disabling their armament on the way in can help you survive to ram. Shoot at key enemy ships, turrets, and torpedo tubes.
- Unlike shells or torpedoes, your target is most likely around the same speed as your own ship. A successful ram against a moving target thus requires sailing to intercept where they will be, rather than where they are now. This is especially true if they have guessed your intention to ram and seek to avoid it.
- Use your consumables aggressively. One way or another, they will likely soon be of no further use to you.
If you miss your ram, or decide to break it off at the last moment, you are likely still in a dangerous situation. Consider the following:
- You are almost certainly not going to get another chance to ram: you are now traveling away from each other, and one or both of you is likely to be sunk in short order.
- If you pre-turn your guns, you can try for a point-blank citadel shot as you pass each other.
- If you have torpedoes, use them. In some cases this may call for turning away from the enemy to get your other side's launchers to bear.
- Consider whether there is another nearby target you would like to try to ram.
The most effective way of avoiding a ram is to not get into a situation where it is even a viable possibility for the enemy in the first place. For example:
- Don't go around corners with an approaching enemy on the other side who might want to ram.
- If the enemy is at a clear disadvantage yet still has significant health left, don't charge him too aggressively.
Noticing a ram threat early will also let you avoid it with less risky actions. If a ram is in the offing, consider the following:
- Decide whether you even want to avoid the ram. For example, your enemy may be making a mistake in ramming, or avoiding the ram may be too costly in other ways. The ram may even be mutually beneficial in ways other than winning.
- If you decide to try to avoid the ram, shoot the would-be rammer, and get your allies to shoot him as well.
- If in a appropriate ship, reverse bow-on. This will greatly delay the ram if done early enough, giving you and your allies more time to sink the rammer, or at least giving you more time to get some last damage in.
- If you have to, turn around. This may give the enemy a shot at your broadside, though.
- If you have better maneuverability, try to fake out the would-be rammer by turning to one side, then the other.
Remember, Total HP Pool is your maximum HP, not your current HP.
- Ramming below 5 knots results in minor damage.
- Ramming above 5 knots results in major damage.
- Ramming damage dealt to the other ship equals your ship's total HP pool (or less if the ramming speed is too low).
- Received ramming damage of at least 10% of your ship's total HP pool will result in flooding.
- Hotel Yankee Signals give -20% damage received, +50% damage dealt.