Foveaux Strait is rough so no trip is guaranteed to be comfortable. What I got was a safe ferry operator who was sensible to cancel some sailings in bad weather. So what? We stayed an extra night and spent a little bit extra? The next day was still a rough crossing but we got back safely.
The boats (different boat each way) were clean and the crew were top quality and did what they could to help all the many sick people (including my children). Thanks.