Complex sentence: The variation of house colors results because fishermen, doing their jobs just offshore, wanted to be able to distinguish their houses with ease and make sure their wives were still home doing the wifely duties.
Split into simpler sentences: The variation of house colors is because while fishermen were doing their jobs just offshore, they wanted to be able to distinguish their houses with ease. This way, they could make sure their wives were still home doing the wifely duties.