Unfortunately, there's a paywall you need to bypass in order to read this article, but maybe there's a way you'll be able to read it (perhaps you're a student and your university library has a subscription?).

Regardless, it's an article by John Pryor, and it's called, "The Transportation of Horses by Sea During the Era of the Crusades: Eighth Century to 1285 AD." It's a detailed and thorough article, and it really changed the way I think about the complex logistics of warfare.