Painting topsides a dark colour

[Frank]

 I'm sure most if not all on here know....but "just in case"....I want to share this story. I'm back at Indian town marina and hope to cross to Bahamas tuesday if the forcast holds. I watched a fellow prep his trawler for paint. Lots of fairing and sanding. He primed it with white and painted dark blue over. It looked transparent and showed white a lot. Solution he thought....more blue paint. A bit better but same effect. Today he's sanding the entire job down and will prime with a dark grey primer. Lots of wasted labour and $$ on primer and paint.
 Moral of the story...if you are painting any dark colour, be it red, blue, green etc....use a dark primer.
 Hoping this may save one of the crew here from the same mistake.

[Grime]

You can also tint the primer to cut the white down some.

My question is. Why paint the deck on a boat a dark color? Its hard enough to cool the cabin with a white deck.

[Godot]

I think he is referring to topsides (the hull above the water line), not deck.  Although I bet having a light colored topsides is beneficial as well to keeping things a bit cooler.

[CharlieJ]

not just beneficial- in the south, painting decks a dark color is insane- you can actually blister feet on dark surfaces here

[Steve Bean]

A little beyond the topic: worst case, years ago a friend of my father's burned his feet on hot pavement in southern California, got gangrene, and lost both his feet.
Steve

[tomwatt]

Most colors indicate in their formula (paint store information) the shade of primer that works best under them... if you check with a paint store, they should be able to give you that info. I also have a study (Sherwin-Williams) that shows tinting primer grey works better than tinting it to a shade of the top color. I think yellow is the only exception, since it works better over a brown-tone than grey tone.
I really like dark, rich colors. But living in The South, I'm finding having black Jeeps to be a problem. Agreed with CharlieJ's comment that you can get a serious burn from trying to walk on a dark surface... having burned my feet on asphalt streets as a kid.

[phil416]

     While painting the topsides of Deep Blue I could find only white primer for the chosen paint Rustoleum Marine Enamel. I went to Michaels and bought a tube of Prussian blue and added same to the Primer.  Let you know in a couple of years how this worked out.  Fair winds Phil

[tomwatt]

You've got the right idea there, although Prussian blue wouldn't have been my top recommendation... it's an older-style dye color, not all that stable.
Actually, to tint a primer coat, best bets would be raw umber, mars black, or mars red. A gray undercoater gives you the best chance of getting the topcoat color to look right, and umbers and iron oxide colors ("mars" black for instance) are all chemically stable and sunfast.
And there's no reason you can't use the same process (artist's oil color) to custom tint any alkyd topsides enamel. Ralph Mayer's "The Artist's Handbook of Materials and Techniques" details the rudimentary basics of paint chemistry in artist's colors (colours for you folks in the U.K.) and provides information on unstable or chemically reactive pigments.