Originally Posted by
AyrMiles
I don't think you mention when you are travelling but bear in mind both of the ferry crossings (unless you take the Eurostar, of course) can be very badly affected by weather. Neither looks very daunting on a map but both the Irish Sea and English Channel suffer from pretty fierce weather during the winter (and at other times, though less regularly).
The Harwich-HvH ferry crosses the North Sea rather than the English Channel (which is a hundred miles or so further south). And in over 30 years of living near Harwich I don't recall a single instance of any of our ferries being affected by bad weather (there may have been the odd one that I don't remember, but it's rare). In fact I have, on occasions, taken the ferry home from the Netherlands when flights were cancelled due to bad weather, and I tend to look upon the ferry as being the more reliable mode of transport.
Also, it needs to be noted that both Harwich and Hoek van Holland are some way up-river - so the ports are quite sheltered, and a stormy North Sea is not going to stop ferries from berthing.