Hi Dave. I am referring to the "14-mile railroad bridge". At mile marker 13.3 on the Black Warrior-Tombigbee Waterway. I will quote from the Tenn-Tom Nitty-Gritty Cruise Guide, "In fact, the biggest obstacle is the railroad bridge at Mile 13.3 which normally is in the closed position. It's a swing span with as little as four (4) feet of vertical clearance in the closed position. Even if it's in the open position as you approach, call him to make sure it stays open. You might as well know, however, that if it's you versus a train, you will do the waiting. Call him on channel 13 in advance. It is called the 14 Mile railroad bridge because it is 14 miles to downtown Mobile. True, most overhead obstructions provide a minimum of 52 feet of vertical clearance at normal high water. But this can change over night if in the spring and raining. We enjoyed the 450 mile trip very much. There are several marina's on the waterway, but are far between when traveling by sailboat. We were in a power cruisier and made marina's by night, but traveled 90 to 100 miles a day. All in all, you will enjoy it and remember it for many years to come. Oh, and I never saw a sailboat on our trip with the mast up. I know several sailors who have made this trip over the years, and all took the mast down. I would do more research before I left with the mast up. A word of caution, after you leave Demopolis Lock & Dam Marina south, there are no services for the next 216 miles. Seriously. Hope you have seen "Deliverance". Just kidding.