large masses of cold iron. Okay so avoid the ironclad steamboats.
Edit: isn't jasmine technically his step mother?

All the magic on Avalon is sensitive to the magnetic effects of cold iron. It disrupts the casting of spells quite a lot, especially if the iron is in motion, as with a sword or mace in battle. The iron has little effect on a stable, completed spell, but Sushi's vixen practice spell is a work in progress, and not very stable. If she bumps against the Dancing Bear's anchor, or that old cannon barrel on the deck, the spell will be broken.

Sushi's new body is not in heat, but it is lactating. That may cause her some unexpected discomfort soon, when the milk pressure builds up.