how to do sailing excursion and also tour island?

Hi,

We'd like to the sailing racing excursion which goes until 12:45, but also would like to tour island. We are in port until 6. Carnival excursion for touring island is in morning, so we'd miss it. We'd like to see Marigot and Phillipsburg, but don't want to pay tons for a private tour. Does anyone know if there would be tours we could take in the afternoon, or how hard and pricey it would be to do own own? It would most likely be me, my husband and our 13 year old daughter doing the tour or exploring the island. She's not doing the sailing, so we have to return to boat to get her. Thanks for any advice!

crewsing with fam, going on Carnival Breeze 8/15/2015