It needs to be at least 18ft to safely fish 3 people. A carolina skiff with a smaller horsepower engine and a trolling motor will be necessary to get back in the flats off the inter coastal. A john boat with a 5hp kicker would be a bad idea for 3 people. We use an 18ft scout with a 115 Yamaha in Pinellas up around Walsingham bridge up to Clearwater pass and it works great for that area. Grabbed it off Craigslist for $5000. Boston whaler makes a decent 16 foot skiff that might be ok for 3 people but that's pushin it. Probably find a used on for about $2000. When you hit the lottery get a 24ft Sterling with two casting decks and a tower.