A magical sailboat

[Anaraxes]

Essential Wood: improve strength and durability

Lighten, if you're willing to extend that from just armor and shields. Every pound the craft is lightened is another pound of potential payload. Also helps greatly with portaging a canoe or beaching a small boat.
Lighten Burden: lighten the payload itself

Find Direction, Tell Position, Tell Time: Navigation. Not necessarily to enchant the entire craft, but a high-magic society might well enchanted part of it, analogous to a compass binnacle.

Test Load, Measurement: The cargomaster would find a tool that supplies these to be useful.

Divination: Weather, of course, but there never was a merchant that wouldn't have wanted to be able to predict prices and availability of goods. Maybe that lucky eye on the bow sees more than we thought...

Weather: lots of useful spells, especially if you allow "portable" area spells for vehicles