Blitz
This assassination is much like the Blitz of Al-Ghul that aurllcooljay and I independently discovered. Again you must lure the target out. There are two places in the shipyard to get a hint on how to do that. Both of them say the same thing: burn his ship. Getting a hint is optional so here I proceed directly to Al-A'eshma's hiding place and climb onto the railing across from his door.
Surprisingly, it's possible to throw a knife at the explosives on the ship from this distance. The key is to enable the "Light Blade" enhancement in Tier Two. Then hold to charge your throw until the knife glows. Finally, aim and release.
Quickly turn around and wait for Al-A'eshma to emerge. Do not press as soon as you see him because this will cause Basim to swing his sword. Instead, wait for the "Assassinate" prompt and do a mini air assassination.
I'm using the word "blitz" here to describe the time between the door opens and the assassination (approximately 630 milliseconds). While the events leading up to this were direct, they were far from what I'd call a speed run.
Dynamic Drop
The new assassination style with a high-falutin name, the goal is to "drop" a net full of cargo onto the target's head while he is moving - thus "dynamic".
First I pre-assassinate all the guards in the area where the final assassination will take place. In doing so, you get to hear one of the hints about burning Al-A'eshma's ship. Then I clear dead bodies from the area. Otherwise, when the target gets here he will slow down to inspect the bodies.
Now climb a mast and set the ship on fire. You can use throwing knives again but from this distance throwing a lit torch is another option. Just aim really high.
When Al-A'eshma emerges his course is somewhat randomized. Sooner or later he will usually pass under the cargo net for a nice dynamic drop opportunity. The first time I pulled this off during rehearsals was hilarious. The target was sprinting from right to left and just got flattened. Unfortunately I wasn't able to replicate those conditions while recording.