Were there plans for a 4th season?

It looked like the season 3 finale two-parter "Flipper's New Friends" was setting the stage for a possible season 4 minus Sandy and Bud and introducing Fran Whitman and her kids. The network probably gave the series the axe anyway leaving the Whitman family (and possibly Porter falling in love and marrying Fran) in limbo.

The evil in this world is made possible by nothing but the sanction you give it. - Ayn Rand