Most likely - at some point in the water one crosses an international or country border much the same as happens on land.
Yes. A passport is not necessary to travel between Ireland and Britain.
Ireland is west of England. Sailing from England to Ireland is relatively short, though it will depend on where you are sailing from in England and where you are sailing to. Depending on that it could take anything from a few hours to a few days. If you are sailing using an actual sailboat, this would be longer than if using a boat with an engine. There are scheduled sailings between England and Ireland by ferry, and more commonly from Wales to Ireland, as Wales is closer than England.
Titanic left Ireland to set sail on April 11th, 1912.
Southampton, England, with a first stop in Cherbourg, France, and a second stop in Queenstown (Cobh), Ireland
If you are sailing within the US, no.
-20
Titanic was sailing from Southhampton in England to New York.
Southampton England to New York, NY, USA
It was sailing to New York
the poem was written after sailing to England
England.
Yes you will need a passport if the sailing is after June 2009. But if you are traveling before that you can still use your birth certificate.