We did that trip last year and are going again this spring. Our draft is 5'11" and we had no problems at all. We departed Ft Pierce early and arrived at mangrove cay around 3am. Forecast
was completely wrong so we were beating into 20plus knots across the stream and the Bahama Bank but all in all a pretty easy run. The depth all across the bank to Spanish Cay was between 12 to 15 ft and very uniform. A few times we thought our depth sounder
was broken. Great Sale
Cay has a nice protected anchorage with several cruisers in attendance. Charts
(Navionics ) were more accurate than I thought and the Bahamas
guide was a good backup. Only time we were nervous was going through the inside passage
from the north end of Elbow
Cay to Tillo cut. Most of the time we would go outside to get to Little Harbor and Lynard Cay ( great little spot ).