He was also riding the Gulf Stream, that peaks at about 4 knots at its fastest areas.
And the water in the Gulf Stream is warm – Lindbergh noted that if Spirit of St Louis had crashed in it, he’d have been able to stay alive a longer time than in other parts of the north Atlantic.
Tangent:
Several people have kayaked from California to Hawaii. Ed Gillette did it without a support boat. It took him 63 days. He ran out of food near the end of his journey, resorting to catching fish and scarfing them down raw. When he landed on a beach in Hawaii, his legs had atrophied, so he could not walk.
Things went down hill from there.
Ed Gillette’s story