You must have some kind of load on the battery
or the solar panel wattage is a big lie. 14W =
about 1A x 6 hours a day = 6AH/day x 30 =
180AH/month.

Larry how 'bout we figure 60AH of usage per weekend x 3 weekends per
month and then the math works!

Seriously now, the only items I use with that single battery are my
depthfinder, GPS, anchor light, and blender. The blender's draw is
borderline for overloading the small inverter I use with it so I'd think
if the battery was ever deeply discharged then the blender wouldn't
break the ice. I've been using the solar rig with this battery for a
coupla years now and have added very little water to the battery. You
mention the solar panel might be overrated, and that's a possibility
since most stuff from Harbor Freight is cheap stuff. All I know is it
says 14 watts on the box.

Totally unrelated Footnote from the Fun Facts to Know and Tell
Department:
The blender is rated at 330 watts. I have 2 different inverters. One
is a 300 watt unit, and the other is listed as 350 watts. The 300 watt
inverter overloads when the blender hits an ice jam, but the 350 watt
inverter plows right on through to Margaritaville! The math sure seems
to work on those ratings.