If memory serves, and sometimes it does not, there was an earlier posting here on the Cruisers’ Net about the free city dock at Fort Walton Beach. In any case, what a deal, assuming, of course, you can clear an 17-18 foot fixed bridge (see below)!

Ft Walton Beach free dock if you can clear 17-18 ft bridge . Low amp electric & H2O available . Length & beam probably not a problem if you can clear the bridge . Airport short hop .
Jim Tharp

There are 50′ bridges at Navarre to the west and downtown Fort Walton (to the east Brooks Bridge) to navigate to get to the city dock. It is indeed free but you must call city hall or after hours the police department to request permission to stay. Numbers are posted on the dock.
Steve Purvis

We stopped here last spring on the way north. We did NOT spend the night but did use the free pump-out, and while I took care of that Jennifer went to the market for supplies. I don’t recall any low (18′) bridge to get into this dock. The free city dock is just off the ICW and just west of the high bridge.
Jim & Jennifer