Dark Hulls and Glass: Boat Air Conditioning Heat Loads
The short answer
Record hull and deck colour, exposed glazing and available shade when sizing marine air conditioning. This site’s calculator adds an illustrative ten per cent allowance for a dark hull; actual solar gain depends on construction, insulation, orientation and shading. Have the installer assess the real spaces instead of applying the allowance as a design rule.
Dark Hulls and Glass: Boat Air Conditioning Heat Loads — Requirements and Limitations
Deck colour matters more than topsides, because the deck is the biggest single heat path on most boats and it faces the sun directly. A dark blue hull with a white deck is a smaller penalty than the other way round.
It is also the load that shade fixes most cheaply. A bimini extension or an awning stops the heat before it enters, and reflective hatch covers deal with the glass. Both are worth doing before you size up, because ten per cent of capacity costs more than a cover does.
Related Sizing, Installation and Service Guides
Each of these answers a different part of the same problem.
- set the hull colour in the calculatorand watch the figure move
- the cheap measures firstshade and covers, with what each costs
- the base figuresbefore the hull and glass factors
- when the boat is losing heat fasterthe fault an unshaded deck creates