there are other sites for this - usually on today's ferrys (the Ben) just boring unless you have a force 8 or 9 then smelly. The old small seacat was known as the vomit comet for its attractions in rough weather (ie for it anything more than a force 6) when it could be likened to a roller coaster hitting concrete and with a shared passenger area not pleasant. The last standard boat boat Lady of Mann was reputedly a good sailing boat but no boat is that comfortable in a force 8 on the Irish Sea where a gale can blow up very quickly. Several postcards I have pre WW1 describe that even during the holiday months some trips were bad; in the holiday months (June to sept)there could be 4 or more sailings a day from Liverpool + others from other ports (Heysham, Fleetwood ..) - you paid on board and queued for first available boat. In winter many fewer sailings as most boats would be laid up - there could be periods in which no sailings for several days on end. If you go back pre steam days then there could be weeks without a boat due to winds + some journies lasting 24hrs or so.