The stumbling block for many can be insurance. I've been there 3 times in the last 20 years and in each case the boat was uninsured while in Cuban waters.
Insurance is more readily available now but you may have to change policy holders to get it. And some companies will not issue a short term rider for say a one time trip.
Here's one way to keep track of many things involving Cuba.
http://cubajournal.co