Red Color Painting of Hulls

[FlyingOnFumes]

Why are the hulls of warships painted red under the waterline instead of dull grey all the way around? Is it simply the underlying color with just the primer without additional paint on top to save weight & $$$ (kind of like Space Shuttle External Tank no longer being painted white and only the primer being left on (reason for the orange color) after STS-2) or is it specifically painted red for a reason?

 

[C420sailor]

It's anti-fouling paint. Keeps barnacles and other sea life from growing on the hull.

 

[skim]

Other ships have been getting a blue coating that help them travel better through the water

 

[CAMike]

The pigment of the anti fouling paint was not specific to a certain goal. Many moons ago the red lead anti-fouling paint served its purpose. That being to kill small sea critters that decided to bond with our hulls. After a short love affair they would absorb some of the lead based paint and would subsequently fall off the hull screaming in low IQ agony. Now we live in a greener world where lead has been replaced with a more environmentally friendly concoction of micro pore slippery paint where the critters have a much harder time hooking up with the hull. The blue stuff that "skim" refers to may be some new fangled KY that the BM's play with- I haven't been in service since 1992 so I'm not totally up to speed on the newest coatings.

BigRed or Steve W. would likely have more up to date hull coating gouge.