I love the animations to this, When you toss the bomb and it sinks. I think it's pretty cool!
Alright, if you don't know where/how to do this and was as clueless as I was, This is where:
Head to Wellson Shipyard. Jump in one of the cannons near the shore.
How: (Lol yes I was confused for a minute on how this works, so I am saying it for those who are like me).
So, this isn't like a click and it'll fire the bomb. No, this is like AoE. You click on it, and click where you want to throw the bomb. Btw, for moving boats, I suggest you put it a little ways in front of it, so that it'll run right into the bomb.
Oh and just a sidenote: Accursed Longshoreman CAN kill your cannon, thus having you get out of the cannon and having to kill it.
You can also get out of combat by jumping in the cannon.
For example:
Say you have 1-5 mobs after you, and you're running to the quest location. Jump in the cannon, And they'll run away back to their original spots.
But... For some reason, the Accursed Longshoreman kills the cannons? I have no idea why. But, yeah. Be careful for those and get the quest done quickly before they respawn.