Not heraldry, but interesting nonetheless. In WWI and a bit in WWII ships were painted in these bizarre, colorful patterns.
I read about this once. I think it was presented as "Wilkinson camouflage", after the dude who came up with it.
The idea was not to make the ship invisible (good thing!), but to make it harder for enemy ships and submarines to determine its speed and the exact direction in which it was moving.
A bit better idea than the ships made of out of ice and sawdust