If you're behind the ship, but too far away, you may have to deal with explosive barrels. The problem is maneuvering around the ship to target the back or front. It's highly recommended to aim low for the best results, but even if you aim low on the sides of the enemy ship, you won't be inflicting much damage. You can also use a strategy of ramming the ship in conjunction with chain guns (also targeting the back of the ship).
For this reason, aim your broadside cannons at the back of the ship to inflict the most damage. It's almost always focused on the sides of the ship. However, this hull plating doesn't generally cover the front or back of the ship. Aim for the Back The higher level ships tend to have very solid hull plating. If you slow down, and even throw in a sharp turn, it's relatively easy to avoid these attacks. In many cases, an enemy mortar attack is aimed to hit your ship in the position it will be in when the shots hit the water, given your present speed. As soon as you see the yellow circles indicating a mortar attack is coming, slow down as much as possible.
The best way to avoid an enemy mortar is to engage at full speed. Keep in mind, once you attack, they will fire their own mortar shots, so be ready to dodge. This gives you the jump and allows you to approach the enemy on your terms. You can hit an enemy ship with mortar shots long before you can engage them with any other form of attack.
Max Range Mortars While most of your battles against high level ships will take place at close range to avoid mortar fire from your opponents, it's still beneficial to upgrade your own mortar attack. Likewise, if you have enough hull plating to withstand a barrage of attacks from a level 60 vessel, but can't make a dent in its hull, you won't be winning that battle. Even if you have elite weaponry, it won't matter if a single mortar shot wipes out your health bar. When you're going up against higher level ships, offensive firepower and defensive hull plating are equally important. The only thing you'd have to worry about are ships outrunning the Jackdaw, and that's something that can be taken care of with a good battle strategy. If you maximize your upgrades, there are few ships that will be able to match your firepower and defensive capabilities.
We're not talking minor hull plating here or a few cannon upgrades. Upgrade! The best and most straightforward strategy is to simply upgrade the Jackdaw. But what happens when you want to engage the level 60 ships, or even the legendary ships? There are a few solid strategies you can use to make these fights much easier. Some are moderately easy to handle, especially the ships around level 20. As you level up the Jackdaw and begin to battle higher level ships, eventually you'll have to take on the Man o' War ships.