If you're looking to cool down your boat cabin, there are a few things you can do. First, open up any windows or hatches that you have to allow for cross-ventilation. Next, consider hanging some damp towels or sheets inside the cabin - as they evaporate, they'll help to lower the temperature. Finally, if you have an air conditioner on board, make sure it's properly serviced and in good working order - it can make a big difference on those hot summer days!