When the 16 was introduced (1970), you could pick and choose between 12 (!) gel coat colors, mix and match your hulls / decks.
Some of the more interesting "standard" schemes were:
Blue decks / green hulls
Gold decks / tangerine hulls
Cream decks / red hulls
and of course,
Regatta blue decks / white hulls - by far and away the most popular.
Hobie continued to produce that scheme into the late 70's / early 80's.
They had problems from the beginning with sun fading - colored gel coat just doesn't hold up to UV radiation. The reds/organges were the worst, so they stopped making those by the late 70's. Green was bad, too. Eventually, the colors were pared down to yellow, blue and white, with a few exceptions. Now you can have your boat in any color - as long as it's white.