Iohannes says, "I am leaning toward Vispilius' approach. Rather than getting technical about areas of the ship, and magi quarters, which might change from journey to journey, it defines your rights and status whenever they are aboard ship by invitation, as well as responsibilities. I don't even want to think about easements! And what he says about the ship being a whole..." Iohannes looks at Vispilius, "gets to the heart of it."
"A written agreement that all can see is a good thing. We can take oath as Vispilius suggests. If I invite a magus from the covenant aboard, I would simultaneously waive some of my sanctum rights regarding him for the duration of the invitation, and agree not to revoke that invitation until the end of the journey or visit, as long as that magus upholds his end of the bargain. I would also agree that whatever authority I have is about mundane captaincy.
"That might still leave the perception problem, but I think mundane laws suggest an approach: a transaction is not binding unless there is an exchange of value, a symmetry. So you would recognize that I have rights as host and ship captain and that ship and crew are part of my magical power, just as I recognize your own rights as magi, and, in exchange for my waiving some of my sanctum rights and protections, you agree to act to champion and protect my ship while you are a guest, which is something I imagine you would do anyway. Anyone who reads our agreement will see the authority and rank I gain as captain balanced or even exceeded by a magus Ex Miscellanea accepting the protection of another magus, and perhaps believe that I traded for this. If they are clever enough, they will see deeper, and appreciate how we navigated through some tricky Hermetic waters.
"As for scrying," Iohannes spreads his hands. "There's an old saying that there are no secrets aboard a ship. I will not pry into your thoughts or try to ferret out your affairs, but some of the crew can see things, and the cats... see deeper. And they keep their own counsel."
Iohannes looks to Scipio. "That kind of subinfeudation doesn't appeal to me; it's been ruinous on land and can only be worse at sea. I'm not a Tremere, but my parens and especially my years at sea have taught me a similar respect for rightful authority and wholeness; I think you would be poorly served by subinfeudating mine. Especially since I think we can satisfy your purpose, and get the best of all worlds."