A roll call is a thread for everybody booked on the same sailing. Start one like this.
Title it so people can find it by searching:
Ship Name — 14 March 2027 — 7 nights Eastern Caribbean
First post: which port you are boarding at, and whether you are after company or just the group chat. That is genuinely all it needs.
One thread per sailing. If yours already exists, post in it rather than starting a second — two half-full roll calls help nobody.
#1·