The fuel vents are at the transom. They can be seen here above the swimstep at the outboard edge. The stbd side has the fuel vent outboard and the FW vent inboard. The swimstep is well above the water at rest and even higher underway.
On the Coot, they are on the saloon sides. Note the two "holes" between the saloon window and engine-compartment air intake:
Edit: OK, I just looked at the pic again in a larger format. The recessed fuel filler (?) looked like an ER vent. Now I see your tank vents.
I didn't do a very good job of describing my fuel and waste tank vents. Here's a better depiction of where they are. Note that the water tank fill is in the cockpit where a fueling mistake (water in fuel tank?) is avoided. Also the hose runs, both fill and vent are the shortest possible.