As we spent more time on the boat at dock, we realized we needed a bit more control of the temperature.
Fans
When staying on the boat during the summer, it could get a bit hot and stuffy. So we bought some DC fans from Amazon. They run off the USB ports we installed all over the cabin, so we can use them whenever and wherever we need them.
Heaters
As the days got cooler, we still wanted to spend the night on the boat, but it could get chilly in the morning. We bought one heater from Amazon, and inherited another from friends who sailed off to Mexico. They are each 1500W and use AC power, so we can only use them at the dock, but they do a good job of taking off the chill.
When we first started using the heaters, we had issues with our battery charger complaining about low voltage. That is how we discovered that we needed to upgrade the wiring between the shore power plug and the AC panel. Now we can run both heaters just fine.