Cor, that's a lot to wrap my head around. And I never properly played the lominsan story arc. But I'll try throwing spanners and logic around anyway...

Quote Originally Posted by Anonymoose View Post
Here's a question:Do you think we're sometimes moving to different ships when someone on a ship triggers an echo?
Yes. We do it all the time. To quote Papalymo, "How the bloody hells did we get here?!?"
But because most lominsan ships are based of a standard (presumably) Naldiq & Vymelli model, the player couldn't be expected to properly identify the differences between various ships.
Quote Originally Posted by Anonymoose View Post
So, that begs the question, when Rusty Steel (Rostnsthal) is travelling around on Hob's cargo ship and triggers an echo... what would he, then Man of Steel (Sthalmann), have been doing aboard Hob's ship in civilian gear when the sea serpent appeared?
In transit, off-duty?
Doing some reconnaissance without wanting to attract too much attention?
On his way back from setting things up with Emerick?

A good officer knows when to put on a disguise and how to dress for the occasion.

^Both of these are of the same character: Belleza, 4th Admiral of the Valuan Armada, specialist in espionage, particularly when it involves getting information out of pirates.

Ok, so my fandom for Skies of Arcadia is filtering through here, but you get the idea...

Quote Originally Posted by Anonymoose View Post
Let's go through some (what I think are) facts (correct me if I make a mistake):
  • Seal Rock truly is Swallowtail Roam.
  • Swallowtail Roam appeared shortly (3 months) before Y'shtola arrives.
  • Sthalmann is Commodore when Y'shtola arrives.
  • Y'shtola is only in town for two weeks in 1562(ish), when the rest of the Circle arrive in Eorzea.
All correct, to the best of my knowledge.
Quote Originally Posted by Anonymoose View Post
Now that you mention it, what IS an Eorzean fortnight?
Don't hurt yourself buddy. Oh, wait, too late...

Quote Originally Posted by Anonymoose View Post
I'm forced to assume that [Y'shtola], herself, is time-jumping around (like she seems to in the Grand Comapny story arc), but spends most of, but not all of, her time in that two week period.
That would be quite a big call to make. Anecdotal evidence suggests that while the circle of knowing is aware of what the echo is, they have no personal familiarity with it before 1562.
Quote Originally Posted by Papalymo, after witnessing the Starshower at the Grand Rite
The echo has sounded, and nothing can stop it now.
Given the way all four members show up at the same time, your theory supposes that Y'shtola's mission in Limsa was different to that of Thancred's in Ul'dah and Papalymo's in Gridania, who sought to find out with what means the city-state would defend itself against the Garleans and get in its way if said means would cause more harm than good. Indeed, Y'shtola's presence can be easily justified with this mission, but your theory suggests she is history-hopping after the fact and the Sharlayan council decided not to worry about Limsa in the way it worried about the other city-states.

I'm kinda not buying it. She's a prowling cat who could have easily got a whiff of something not being quite right around Merodaulyn and decided to stow away during the expedition.

Um, yeah, I always figured that second appearance of Leviathan with the tidal wave following the ship fight was the seal rock expedition. Please correct me if I'm wrong there.

Quote Originally Posted by Anonymoose View Post
I'm bothered to a very great degree by the fact that, in order to make this work, I end up having to assume that Sthalmann went from deckhand to Commodore in three months. STILL, when you take the Trident into consideration, you can go from pirate to Admiral in a day... (Lookin' at you, Merlwyb!)
I'm looking at Merlwyb as well. She's held the chair for ten years now, it seems. Which leads me to a new question:
How often is the Trident held?
Is it a yearly thing? Or does it only ever happen when the previous Admiral falls off the chair (natural or assisted causes)? I'm gonna hazard a guess with the latter, and that makes me buy the "ascension to commodore" theory even less. Nah, that guy has been plotting for a long time. He also has the air of confidence and the respect of his underlings that you have to build up over years, not just three months.

At the very least, he was first mate to his captain, not a deckhand.