I have 1 for voyages and 2 for crew, but no idea what they do... Do they just give me new voyages or does it reset the daily limit of how many voyages I can do, which I think is like 14? Thanks

Voyage reroll : adds 5 extra voyages for today.

Say, your day just started, it says "Voyages available : 15" - it will go up to 20. (I would use them only when you already ran out of trips)

 

Crew reroll : same deal

ok interesting, not sure how I got them, obviouslt the voyage ones are worth a lot more than crew

You get them from random events