Nope, not limited by presence, just by area and a MR check for living and animated beings

So yeah, you could walk around with a Nimitz class carrier
IF you have the INT to cast it
Levitation SphereLevel: 70-80
Action: Active
Type: Spiritual
Effects: This spell causes objects and creatures to levitate. The caster can decide what will levitate and what will not, regardless of weight or size. Objects or people suspended in the air are moved by the caster with a Flight Value 6. Those wishing to resist the effects must pass a MR check. Only animated or live beings are entitled to a Resistance Check, as are constructions endowed with supernatural characteristics.
Casting Level: Base Intermediate Advanced ArcaneZeon: 150 200 250 300
Req. INT: 8 11 13 16
Base: MR 80 / 25m Area
Intermediate: MR 100 / 150m Area
Advanced: MR 120 / 250m Area
Arcane: MR 140 / 350m Area
Maintenance: 15 / 20 /25 / 30
DailyClosed Paths: Earth, Water
So no presence or weight limit, but getting to 16 INT for a Nimitz (333m) isn't that easy

Of course, there are ways around it such as CP advantages and Rituals, but walking around with that thing isn't a good idea... it can be done though
