First Atlantic crossing by boat

First ocean crossing by boat? Surely the skin boats used by the Irish and some of the Pacific people were capable of ocean crossings. I have sailed on the Atlantic myself for many years and met at least six people who crossed the Atlantic alone in small sail or man powered boats, so I know it can be done. The technology was there 2000 or more years ago, so why not sail the ocean rather than wait for some "land bridge"?