It’s easy to carry along a six-pack or two of beer on ice when you’re cruising Casco Bay on a hot summer day, but that other thing you’re likely to crave as the sun beats down on your forehead – ice cream – well, that’s not quite as easy to take along without making a gigantic mess.

Ashley Rutherford to the rescue.

Rutherford, a 34-year-old medical practice manager who lives in South Portland, is launching a new business this weekend selling ice cream from her boat on Casco Bay. Rutherford already spends a lot of time on the water – she holds a recreational lobster license – and when it gets hot, she craves grape popsicles. Figuring other people feel the same, she decided to start her own business, stocking her 20-foot Mako with Italian ice, ice cream cups, Snickers and Twix ice cream bars, freeze pops, ice cream sandwiches and similar treats.

“Anything an ice cream truck would have,” she said, “that’s what I want to have.”

Sea Snacks will make its first rounds on Sunday, but most weeks the floating ice cream truck will be out on Casco Bay Fridays after 4 p.m. and Saturdays and Sundays from 11 a.m. until dark. Rutherford plans to hang out part of the time near the island piers where the Casco Bay Lines ferries pick up passengers, but mostly she’ll cruise in the area between Peaks and Great Diamond islands, where lots of boaters, kayakers and paddlers pass through.

“That’s very busy,” she said. “There are three piers, and you can see all of them right there.”

Once upon a time, sailors navigated with sextants or by looking to the heavens, using the stars to plot their course. Boaters on Casco Bay who would rather plunder popsicles than pirate booty will be able to rely on a more modern tool to locate the sweets they crave: Rutherford plans to post her up-to-the-minute location on the Sea Snacks Facebook page.

If you’re out on the water, look for a big blue-and-pink flag with two ice cream cones on it. The flag says “ice cream” in big block letters.

You might also look for more than one person dishing out the goodies. Ice cream-loving friends who have fallen in love with Rutherford’s idea – or who, we suspect, love the idea of a summer day spent on the water – are volunteering to be her helpers.

Even her 5-year-old nephew has offered to be a member of her crew. How many freeze pops will he accept in lieu of a paycheck, we wonder?