The time it takes is one thing, the other I expect is the cost. Is there really an alternative still running ocean transport between Europe and the US? (and not getting on a container ship Michael Palin's Around the World in 80 Days style)
Yeah QE2, costs about the same as an airline ticket last time I checked. For some people who are terrified of flying this is how they manage to visit the US/Europe.
Cunard. Prices aren't as too terrible, basic rooms are ~£1000 per person one-way.
I'm not sure about a regular ocean transport, but you could take a cruise ship between Southampton, UK and Key West, Miami or New Orleans. They're not particularly regular, on top of the additional cost/time constraints.
Even if you had the time (five days on the QE2 from Southampton to New York) there's not a lot of choice with schedule.
With a travel time of 5 days I assume you won't arrive jet lagged? I think that compensates for lack of schedule choice.
With the plane you can spend 2 days recovering from jetlag and still come out ahead.
They change the clocks an hour daily, so it is pretty easy on the body clock. More so in one direction than the other, of course, but still better than flying.
I'm curious where you saw that figure of 5 days. Everything I've seen is 7-8 nights, e.g., depart 9/9 and arrive 9/16. That doesn't substantively change your point; I was just surprised to see 5 days.
They can do it in 5 days, but most of the time they want you on there longer. It means they can both conserve fuel, and have you spending money for longer once you're captive.
Source: I worked on cruise ships for a couple of years. FWIW the crossing I did with Holland America took 6 days.