As far as I know, this is the fastest way to Captain Trugust:
1. when you enter the dungeon talk to the lady npc.
2. after talking to the lady npc > go to the place where 2nd syasor is and find first muchaa then kill it. (note: you must kill muchaa first and loot the quest item then talk to the lady npc that'll appear before you make the 2nd syasor appear to gain the quest for the captain trugater's boat.)
3. then after that. do the next quests up to where morsus will be appearing at the entrance of that boat
.
4. voila! kill the captains :P