By boat, yes, if you're willing to row a lot or have a really big gas tank for your outboard motor, LOL!
Anyway, I changed your question because a boat is a very small vessel, while passengers are normally carried on ships. The only ship line with regular service from the U.S. to Europe is Cunard, who operate the Queen Mary 2 (and soon the Queen Victoria) from New York to Southampton, England. From there you could easily transfer to Ireland.
Some lines operate what are called positioning voyages, on which a ship makes a special trip from say the Caribbean to Europe at the start of the fall season. These trips normally carry passengers (after all, those big things cost lots of bucks to run) and sometimes stop at other ports. Your best bet would be to go to a good travel agent who specializes in cruises and ask more questions.
Yes, US citizens need a visa to travel to Ireland.
The travel time from the US to India by ship can vary depending on the route and speed of the ship. On average, it can take around 20-30 days to travel by ship from the US to India.
Yes
West
Before planes, they would have got there by ship.
The only other way is by sea. You could sail your own boat or go on a cruise ship. You may first have to travel to another country to get a cruise, depending on when you want to travel.
Yes, as a US citizen, you do not need a visa to travel to Ireland for stays of up to 90 days.
By ship and aeroplane.
No you can't. Ireland is an island. It is on the other side of the Atlantic Ocean to the US. It is over 2,800 miles away. To get to Ireland from the US you would have to travel by sea or air.
not if you are traveling back to the us on the same ship
it would cost you $5287 to go from the US to London on a ship.
Typically between a month and 6 weeks.