This summer has been very hot in Maryland. The outside air is incredibly hot and humid, making any desire to go sailing on the weekends wither and die. Our top priority is to keep cool and stay comfortable while this heat wave blows by.
We have air conditioning installed in the boat, which cools and recirculates the air presently in the boat and an active and passive air circulation system which keeps the boat filled with fresh outside air.
We keep the air conditioning set to 68 during the summer and the unit is able to keep the boat around 70 to 72 degrees Fahrenheit. During this heat wave, the air conditioner was struggling to keep the boat cool as the interior temperature reached 84 degrees! We need to take some steps to help it out.
Our first step is to tackle the air circulation system. The active air circulation is powered by solar fans which draw the interior air out. As the air is drawn out of the boat, the passive air circulation lets fresh air enter the boat via a series of vents.
We decided to leave the head's air circulation intact. This consists of a dorade vent to let air in and a solar fan to draw air out. Our composting toilet likes the air to turn over and circulate, so this setup can be left alone as long as we keep the door closed so the heat doesn't enter the rest of the boat.
The other dorade is in the hallway that connects the forward berth and salon. It also lies right over the air conditioner intake. Air from this dorade makes its way through the boat and then exits via a fan above the galley, also keeping a fresh turnover of air inside the boat. During colder months, this constant turnover of air helps keep condensation issues under control, but we don't have to worry about that with the summer heat.
Maddie and I noticed that the hallway was significantly hotter than the rest of the boat. The heat also became more intense as you moved your hand closer to the vent in the deck where the dorade feeds.
Dorade vents are typically screwed into the dorade box and held in place with a set screw. Simply loosen the set screw and unscrew the dorade vent to remove it from the box.
We then covered the dorade vent hole with a cover plate that screws into the same threads which hold the air scoop on. These covers are meant for heavy weather use, when raging seas are expected to swamp the deck and fill up the dorade box. Dorade boxes allow air to enter the boat while separating out any water, letting it drain out through the weep hole visible in the bottom right corner. If a huge wave were to fill the box faster than the hole could drain the water, water will then pour into the boat and soak the interior in salt water. In these situations, replacing the vent with a cover plate will prevent the ingress of water and keep your interior dry and clean.
We have never needed to use these cover plates before, since we heave to in heavy weather and don't take waves over the deck, but we had them in a locker and I knew right where they were.
As soon as I installed the cover plates, the heat in the hallway vanished and the interior temperature in the boat started to drop. In a few hours, the temperature was 71F and the air conditioner doesn't need to run as often either.
During these hot times, keeping cool takes priority over sailing. It certainly is nice to be plugged into shore power in a marina while living aboard!