The point I'm making is that the timeline doesn't fit.
The number of people who could deliver an explosive capable of sinking a Dwarfen Monitor in seconds is very, very short. The fact that the gunmen retreated after only a volley or two is very telling.
Why?
Because it means they either had no idea who they were attacking and booked it as soon as they realized (Oh fuck we're not getting paid enough for this)
or they kept shooting without a care because they were elite regulars, and... To be honest? That's an absurd risk to be taking if it was Marienberg. You don't send your actual elites with actual discipline in to tweak the nose of a superpower, you use cut-outs and patsies, who you intentionally can set up to not know who their employer is. Or suggest your employer is someone else.
Either way, the trail goes cold there.
However, our attackers are... Unlikely to anticipate a very intelligent, very perceptive Grey Wizard is able to be on the scene within hours of the incident, with the best Windsight since Volans himself (Which Mathilde has kept under her hat). There is a chance that she could identify shenanigans going on before the water and currents wash away the traces of the explosive. Because guess what? Contact explosives are really, really fucking hard with this tech base! Firepower enough to send an ironclad vessel crafted by dwarf memes to the bottom before anyone could react? Very short list. To the point where there's only two factions I can think of who have both the technological know-how to set up the required detonator and the material science to create a suitable explosive, and both are likely to have telltale signs at the site of the boom.
That's worth the risk, that's a very depreciating asset. And it's why I take this obsession with chasing the obvious diversion with great terror.