You can't sail from London to Cologne.
about 4 hours probaly 5
4 days
3 hours about
About six and half hours. See related link.
2 days
No longer than 1 hour 30 minutes
several days
6 and half days
approx 72 days
6 weeks
it takes about 2 hours by flight but im not sure how long it takes you to sail :/
If you are a sailor you will know the answer to this question. If you're not a sailor, don't try it.