If an when he's satisfied that he carries no more taint of the diseased wood, Vispilius shifts and settles onto the deck, and steps off the stave, willing it to follow some distance above and behind the ship.
"I can turn any of the corpses to dust, but beyond that my ability to affect the ship seems limited. And even from nigh onto it, not to consider from this great range."
There is a sound, like a hollow melon struck with a boot, but amplified a hundred times. The ship across the way gently puffs into a fine ash, and begins to be swept away, like thick smoke on the sea breee.
In the space where once the ship lay, a mass of human bodies, stacked like corded wood out of the weather, hover for a moment, before the corpses cascade into the water. They float easily, perhaps because some are puffed with the gasses of decomposition, and they begin to slowly stroke after the Sanctum Mysterium, despite its far greater speed.
(and yes, Vispilius's hands now look perfectly clean)
After 'curing' Vispilius' hand Scipio offers a formal bow followed by a couple of steps backwards, away from the other Magus. He watches the effect of his casting on the other's hand from this distance with keen eyes and hands & arms being pulled back under his cloak, nodding to himself after a moment.
(Here I assume (Correct me with prejudice if I am wrong.) V. says something to the effect of 'it worked' and 'thanks'. )
Scipio doesn't seem to give it much thought. "Of course." he is obviously however already moving onward in his thinking.
Afterwards he comes back to the fore to stand with Iohannes, watching the enemy vessel and his preparations with equal shares of his attention. Now his sergeants rejoin him, his work with Vispilius done... forming up a bit loosely in the heavy movements of the ship.
Scipio watches Iohannes' feat of spellcasting with some obvious doubt on his features... then a slight widening of his eyes as the ship crumbles into powder. A nod of approval is given to the now fatigued Magus. "Well done Comrade." he says, folding his arms over his chest.
Then as he watches the mass of bodies tumble down into the water and continue thrashing/flailing his expression darkens once more to mask of disgust. "The have no appearance of giving up the chase, as you ( Iohannes ) suspected. There are many of them, however long it might take them to swim anywhere. It will be laborious more than challenging, yet we should destroy them now that we have them at such a disadvantage. At the very least our enemy will have to replace them before attempting any similar feat. And hopefully by then the vessel will already be protected by my Aegis. As we are in no extreme danger and may slow our pace now, perhaps it would be wise if I layed it on the vessel before we drew near the creatures for the final blow. Unless you have any differing orders?"
Indeed Vispilius confirms the success of Scipio's efforts, and likewise offers his thanks before, finally, settling aboard with some obvious relief.
"Well done indeed." He looks at the drawn visage of their captain. "Tho' I believe, true to his word, that Iohannes is done casting any sizable spells for the day."
As the death ship evaporates, and the mass of ersatz humanity falls into the ocean, there is a further tension gone from his posture and visage, as that pressing threat vanishes. At Scipio's suggestion, a pause followed by a slight slump of the shoulders prefaces Visiplius' response.
"Hundreds of them?... 'Tedious' is one word for that, yes... perhaps an apt one. Won't the sharks and other creatures of the deep dispose of them? And if not, even were they to follow us to shore, what...", and here he pauses, wheels whirling in his mind, "... unless they carry a Corpus infection similar to the Herbem one we just witnessed..."
He lets out a great sigh, and looks around at the collection of magi.
"And am I, then, the only one who can attend to this matter?"
Scipio nods after a moment, sighing. "It is my thinking, likewise. These are creatures of Infernal Taint. It would stand to reason they may have the capacity to likewise spread their Corruption if not checked. And I do think you are most suited to the task. Though I am also able to assist it seems. Which is one reason I suggest getting the vessel into a state calm enough that I may ward it. Then I would be confident we could pull alongside the mass of them and destroy them at leisure. Or do you provide another option?"
Vispilius gestures toward the stave that he had ridden, that still hovered some distance above and behind the deck, occasionally drifting closer or further, but occasionally re-synchronizing its course with the ships at a thought from the mage.
"With me, or on your own that I would control. I brought two back in one piece, and while concerned with the ship. Simply hovering over the water and shooting dead fish in a barrel is nothing too challenging, so long as you need not touch them, which I think we agree would not be advisable."
Scipio eyes the hovering stave with a dubious expression. Shaking his head slightly he smiles after a moment. "I think I prefer to keep my feet about me for now. Perhaps in the years to come I'll craft my own means to accompany you."
Vispilius lets slide a smirk, and with an exaggerated tone, replies
"Oh, well, of course, if you're not up to the sort of challenge that my house is accustomed to, I understand completely..."
The stave slides over near the deck, and he swings a practiced leg over, and soon is off again, hitting the corpses that he sees with Dust to Dust, and trying not to count as he does so...
[ OOC: Any objections to the raising of the Aegis on the ship at this point? ]
OOC: Not by me.
Titius tries to aid in any way that he can. His skills are rather limited so he tries to look as if he could contribute with anything. Perhaps stride towards the rail and cast the odd pilum of fire upon the living dead.
Before Vispilius leaves, Iohannes suggests, "If we leave one or two of them mobile, we might experiment to see what it is they are chasing. Is it the ship itself? Someone on the ship? Something? It might be worth our while to take a page from Jonah and find out."
The mage causes his broom-like mount to hesitate just off the ship, already partially lost in the fog to all but the caster.
"This won't happen quickly. I'll leave the nearest ones for you to play with. If you make a decision or need additional help, I'm sure you can contact me."
None here.
Iohannes nods, and after a moment says, "Aye."
To Scipio, Titius and the crewman in active command, "It will be almost two hours before I'm rested again. Meanwhile, and before we continue to Visby, I want to see what these swimmers are chasing.
"I'm thinking about sending the small boat off a little ways from the Sanctum Mysterium, with a few men in it, and then see if the swimmers change course. It's a good thing we don't have much in the way of cargo, but we can do the same with our guests and their personal effects, until we know. This will take a few hours but might more than pay for our time.
"Any thoughts?"
(Timothy, if there is general agreement, we make this happen and see what the zombies do. BTW, are the cats doing anything worth Iohannes' notice?)
[I'm pausing for general agreement. Unless anyone objects in the next day, we go on. The cats are interested in what is going on, and are watching from various locations, but are not doing anything yet.
By way of warning regarding the cats, I have a new source of inspiration. Linda and I have just bought two kittens, and they so far have demonstrated a mystical power that allows them limited invisibility, and the strange ability to make you forget that they have just tried to climb you like a tree and left clawmarks in you.]
[OOC: If the agreement consists of A) Aegis on the Ship, B) Experimenting to see if we can determine who or what the zombies are after and C) Destroying all the zombies we can find... then I agree. If it doesn't, then I'm lost. 
]
[As you suspected, they are chasing the small, close boat, rather than your large, distant ship.]
Who and what is on the small boat when we notice this?
From here, we narrow down to whether they are chasing the closest or furthest, and exactly who and what they chase, separating people as needed.
(Liberal use of Rightful Authority and even Slumber, if our guests balk.)
Titius tries to cast whispering winds to determine who those on the small ship are and perhaps True sight of the air if he still needs it to see the small ship. Whatever of usefull information he finds out Titus tells his fellow magi.
OOC: Both are InAu 15 and the casting total is +5.
Just to clarify: the small boat is one of the ship's boats of the Sanctum Mysterium. You already know who is on it, because they are crew selected by the characters.
To answer Ken's idea: they are seeking the closer object, provided it has anything living on it at all. This includes cats, but not potted plants.