Just been in it, it has a walk in area. To see the Doctor is $149, plus medication, but you can seek nurse advice and buy items over the counter like a pharmacy.
They can undertake " first aid" IE emergency and stabilisation, it has a bed and x Ray, but limited, if serious there job is to look after you until a helicopter or SAR boat, or the ship can dock, and that's it.
They have regular hours like 9 am to 11 am and 4.30 to 7 pm, or just call in an emergency.