Between us and the ocean was the 17th Street Causeway Bridge. We found out that we could barely slip Shibumi's 56 foot mast under the 55 foot bridge, at low tide. The tide was low and the bridge would not open for another half an hour so I inched forward on the thottle and slowly passed beneath the steel and concrete spans. Jill stood watch as we approached the bridge, but it was impossible to tell from our deck we would clear. We cleared with nearly two feet to spare.