The peer-to-peer rental concept popular among travelers has gone pier-to-peer.Like Airbnb.com, where homeowners rent out a room or the whole house to vacationers, boat-sharing websites give landlubbers who want to spend a few hours on the water an online marketplace to search for boats of various sizes and prices.Instead of going to a boat charter company, potential renters log onto a website such as Boatbound.com and connect with boat owners directly. For the owners of the vessels, it's also a way to make some extra cash off their boats when they're idle."I am a captain and I like to see people on the water and Cruzin gives people a chance to get on the water," said Tom Dwyer, 73, a Florida resident who lists his two kayaks and his 20-foot and 30-foot Albury Brothers boats on Cruzin.com, which launched last year. His smaller boat, called the Risky Business, rents for $200 a day. He said it's a way to keep his boats running when he's away.Jaclyn Baumgarten, a co-founder and chief executive of Cruzin, said that "with peer to peer rental, it's a way to take that natural community that exists offline among boaters and bring it online. It's about that social experience. I think boaters are naturally social people who love spending time with friends and family."The San Francisco entrepreneur, who lived in Hollywood, Fla., to launch the platform, got the idea for the company after seeing her two brothers wrestle with the possibility of having to sell their boats because of the high maintenance costs associated with them."I knew about Airbnb and car-sharing models," recalled Baumgarten, who thought the sharing economy could "create a safe experience for the renter and the (boat) owner."Baumgarten also wanted to make boating more accessible for everyday folks. She decided to launch the company in south Florida to see how the concept would work in a region known for boating."We knew that if we could build a program that would work for Florida, that it would work anywhere," she said. The company has since expanded nationally.So how does it work?Boat owners log onto Cruzin for free and create a profile with photos of their boat, size and rental fee. Renters use the site to browse for boat style (from kayaks to yachts) and price.An online map features the image of a small sailboat that marks where there is a boat available. On a recent weekday, there was an 18-foot Tahoe Q3 rented for $150 a day, while elsewhere, there was a Stingray available for $200 a day."These boats are privately owned, well-loved and well-appointed," added Baumgarten. "They are much nicer than what one would find in a typical rental fleet."The company prequalifies renters using Experian and fraud-prevention checks. The customer also has to have at least two years boating experience, which they explain in the screening process, or they can bring a licensed captain. The boat owners are also protected by $2 million in hull insurance and $1 million in liability insurance and towing service. Cruzin gets a 40 percent cut and covers the insurance."It's safe, easy and fun, just the way boating was meant to be," Baumgarten added.Other sites, Boatbound.com and fun2boat.com among them, are taking a similar approach in matching people with vessels.BoatSetter.com launched last February and rents boats in the 28- to 60-foot range regardless of one's experience. Recently, an eight-passenger, 28-foot boat in Boynton Beach was going for $126 an hour.The website lists designated marinas and areas to rent from. The site also matches people with captains for hire if the renter prefers to have someone with more experience aboard.Former boat owner Julian Lopera was looking to charter a 23-foot-power boat recently. He decided to try Cruzin."I wanted a powerboat just to go out with the family for the day," Lopera said. He spent about $420 including gas to rent the boat from an owner who showed him the ins and outs of the boat.Lopera took the boat out with his wife, two young boys and other relatives."They loved it," he said. "It's definitely better to rent a boat than to own one."