He had spent more than 20 years in the hospitality sector, working his way from valet parker to vice president of operations for Annapolis valet parking firm Towne Park.
Snag-A-Slip contracts with marinas for a few slips of various dimensions to ensure enough listings are available. Staff take pictures and review the facilities and amenities. If the site gets a reservation, the company takes a cut of the booking fee from the marina, rather than the boater.
More than 80 marinas in the Chesapeake Bay now have listings on the site, which spent more than two years in development, Cowens said. Snag-A-Slip hopes to work its way south to Florida by Thanksgiving, with more than 250 marinas on board by the end of the year.
"We've had such an overwhelming response that we accelerated the three-year plan," Cowens said. "It's been a whirlwind, and we've just had to continue to move that horizon and set new benchmarks down the road."
The company isn't entering completely uncharted waters. Marinas.com, which dates to 1995, has a database of marinas, and Marina Life, which dates to 2000, offers a centralized booking platform.
Newcomers also include Rhode Island-based Dockwa, which this spring said it raised more than $1 million in seed funding for an app-based booking platform.
But listing and finding slips remains a fragmented process, with most people calling individual marinas to book trips, sticking with places they know, or relying on referrals from other boaters.
"I would want to use it if I knew about it," said Hesterman, a Delaware resident who plans to stay in Baltimore for a week. "It would be helpful because if you want to find a marina now, you have to specifically know the name."
Michael T. Morgan, president and owner of St. Michaels Marina, agreed to list his marina on the site after Snag-A-Slip approached him about a month ago. So far, Snag-A-Slip is responsible for a few bookings, and he didn't mind the charge, he said.
"If they can find a boat out there that normally wouldn't use a cruise guide or call the marina but is digitally active or Internet-savvy, I'm all for it," he said. "That's a customer I wouldn't have otherwise."
Morgan said technology has been slow to affect boating practices, in part because the pastime requires a degree of wealth, which often comes with age. But that's bound to change.
"As the younger generations … come into money, they're going to be more inclined to be on an iPad than reading a cruise guide," said Morgan. "I think it's a super idea. It's absolutely the future."
Cowens said he knows it will take time to build trust and change the behavior of both marinas and boaters. He declined to discuss financial details or specific reservation numbers, saying he was worried about giving information to a competitor. But, he said, more than 80 percent of people who've used Snag-A-Slip return to make another reservation.
Cowens, who served in the Army and started the company with classmates from the executive MBA program, said he expects the company to grow from eight full-time staff to about 80 by next summer.
Right now, he's funding the business through a combination of savings and $50,000 in startup funds from a Salisbury University entrepreneurship competition. The firm is in talks with investors and trying to raise $2 million, he said.
The company also is testing future iterations. One possibility would be to create a marketplace like AirBnB, where long-term slip holders could offer their spot directly to another boater instead of through marinas.
"I can't tell you too much about future vision," Cowens said. "We want to build out the next version as it makes sense and the industry is prepared for."
On Monday afternoon, Larry Gundler brought his sailboat into the Inner Harbor Marina, a spot he's frequented for more than 30 years. Gundler said he hadn't heard of Snag-A-Slip and isn't sure about demand for such a service. Many boaters, like him, head to marinas they know or are forced to stop where there aren't a lot of options.
But, he said, that could change.
"I'm not saying no," he said. "In the future, sure, everybody's going to be used to that sort of thing."