The biggest drawback is late afternoon when the sun goes low. We were on a mooring last night in Camden Harbor, and the thermometer in the head(coolest place below and on the shade side) read 86 F at 4 pm. We didn't rig the awning because I know our orientation would make it useless. You had to escape the sun or swim(still a bit bracing for me)

The only escape was to sit on the shaded side deck(thankfully they're wide), and catch the breeze. When the wind blows off the land(west), even our 60 degree sea water that air conditions the Maine seabreeze, has absolutely no cooling effect until you get a mile or more off the coast.

This is a useful solution for low afternoon sun,... if you have it available.