Rainbow was designed by W Starling Burgess and launched in 1934 from the Herreshoff yard where she was built in just 100 days. The yard workers were happy to have the difficult and sometimes hazardous work as the US was still in the throes of the Depression.

Rainbow was narrower than Enterprise and wider than Weetamoe with a hull of bronze plate over steel frames below the waterline and steel plate above. The J stepped a pear-shaped duralumin mast designed to take the strain of the double-headed jib — first used on Whirlwind — and she was originally rigged with a Park Avenue boom which was later removed because it was considered too heavy.

Rainbow's challenger, Endeavour proved to be the most able vessel yet to challenge the US for the Cup. Endeavour decisivly won the first two races and narrowly lost the third to Ranger. Ultimately it was the skill of Mike Vanderbilt as a skipper and that of his crew that made the difference as the US yacht won the next three races by small margins and defended the Cup.