There is only 1 cross over( other than the 7 mile bridge ) on Marathon and that is at the Vaca Cut next ot Capt. Hook's dive/bait shop. This is at the 53 MM on Hwy 1.
This is a low over head
bridge and will not clear a sail boat
The only way "around" Marathon on a sail boat
is via the 7 Mile Bridge.
enjoy the wind
for it is free