All the ships I’ve done were two musicians to a cabin, not three. Bandleaders get singles. And it is in no way trivial; your living situation can have a huge impact on how well you enjoy your contract.

The cabins are indeed pretty small, and how well you get on with your roommate can make or break the experience, depending on how adaptable your own disposition is to this kind of thing. I have had two roommates so far who had drinking problems, and while I liked them personally, it can be cumbersome to deal with this kind of issue. A lot of ship musicians deal with this by spending very little time in their cabin…they get off the ship when in port, go to the gym, attend some of the daytime activities where permitted, or just watch the scenery. Oh, and practice. Some people do that too.

Non-eq tours are also double occupancy, but at least you’re in proper hotel rooms and it can be much easier to switch roommates if issues do arise, depending on how flexible the company manager is. Also, while musicians (even conductors and tech department heads, increasingly) do typically share rooms, you also would have more power to negotiate otherwise once you have a good relationship with the company (caution: individual results may vary!), whereas ships are almost totally inflexible about this.

I don’t know how most union tours are doing it these days, but at one time it was common practice to be paid a per diem for your housing costs instead of the company providing lodging. That way, you could make your own arrangements, and people often opted to share anyway and pocket the rest. (You would “officially” owe taxes on the pocketed amount…) Or, you might be offered a choice of company lodging versus a buy-out for the same value.