Got a boat? You may need a license.

Getting ready to leave all his everyday worries behind, Jeffery Bard energetically preps his 26-foot powerboat, "My Way," for a sojourn across Oyster Bay. For him and millions of other skippers, a day on the boat is one of the few ways left to disappear, to become just another zooming dot on the glimmering horizon.

But the days of the autonomous and anonymous sailor may be numbered. The US government, eager to improve boating safety and plug holes in a largely unguarded coastline, is considering requiring all states to license boaters or possibly mandating that all boaters obtain a federal photo ID.

Some skippers are offended at the idea of the government following too closely in their wake. Others, including Mr. Bard, are more sympathetic. "Right now, you don't need to take any courses, you don't need to take any tests, anyone can get behind the wheel," he says. "It's harder to drive a boat than it is a car."

Indeed, the trick to extending vehicle licenses to vessels, terrorism experts say, is to walk a thin plank between precaution and the civil liberties of boaters – a group whose tradition is to slip away from the dock and into anonymity.

"As we look along the coast and along the water, the issue of recreational vessels is the next logical step when considering potential gaps in security," says US Coast Guard spokeswoman Angela Hirsch in Washington. "The goal is getting a better understanding of who's out there."

With some 17 million boats on the water, as many as 70 million boaters, and 95,000-plus miles of shoreline, America has a coastal vulnerability that extends beyond the few miles of range around major ports that the Department of Homeland Security (DHS) has secured so far.

While the federal government will spend $178 million next year to attain a goal of placing radiation monitors at 98 percent of US ports, many experts say a jihadist cell would be less likely to ship a nuclear device in a container and more likely to deliver it in person in a recreational-style boat.

The attack on the USS Cole, for one, showed that small boats such as bowriders and cuddy cabins can be used to ram large ships and to launch mortar attacks, terrorism experts say.

"We've been doing relatively little, if anything, on the thousands of miles that are the unmonitored and uncontrolled coastal borders," says Henry Willis, a Pittsburgh-based policy researcher for the RAND Corp., a think tank that has studied America's coastal vulnerabilities.

Enter a boater's license. Currently, states regulate small vessels, and only two – Alabama and Connecticut – require licenses for boat operators. Attempts before 9/11 to introduce a license in Utah, which has no coastal waters, failed as legislators moved to protect "the last frontier" from onerous regulation, says Ted Woolley Jr. of the National Boating Safety Advisory Council.

"People don't think about boating the same way they do about driving a car," says Lt. Erica Shipman of the Alabama Marine Police.

The US Coast Guard has been advocating legislation that would give the federal government power to require safety classes and a completion certificate for all boaters, but it's currently stalled in Congress. In speeches, Coast Guard Commandant Thad Allen has broached the idea of requiring all states to license boaters.

"We don't want to make the protection against a small vessel ... so onerous and burdensome that we destroy your livelihood or your pleasure in [boating]," DHS Secretary Michael Chertoff told 300 boaters and industry folks at the Small Vessel Security Summit in Virginia in June.

At the same time, pushing through boater identification has become a priority at DHS. In March, the agency implemented new maritime-worker identification rules at 98 percent of US ports, and it is looking at controlling secondary threats from Cape May, N.J., to Catalina Island, Calif.

"It's true that boats are potential instruments for terrorist use, so [boat licenses] are a way for the government to zip up the country as much as they theoretically can," says Dennis Pluchinsky, a retired State Department terrorism expert.

Some boating groups accuse the US of trying to build an onerous bureaucracy that would punish boaters instead of bolstering the Waterway Watch, a post-9/11 citizen action program that taps boaters as eyes and ears on the water.

"What concerns us is that [DHS] is trying to basically use boating safety as a fig leaf to cover their real intention, which is to identify recreational boaters and get them licensed," says Mike Sciulla, spokesman for the Boat Owners Association of the United States in Alexandria, Va. "For the government to suggest that boaters should be required to take classes for national security reasons is ... unwarranted."

Back on the docks at the Oyster Bay Marine Center, sailboat owner John Domenech says such a law must be approached carefully. Would it, for example, affect the ability of his 16-year-old granddaughter to pilot a rubber dinghy around the harbor, he wonders. His friend, Ken Keighron, says "old-timers" should be grandfathered under any new licensing law.

Out in the harbor, a breeze is blowing, cooling off Richard Cassano as he gets his 40-foot sailboat ready to head to Maine. A few weeks ago, he says, he would have been against any federal ID law. But now, after a near-crash with an erratic 50-foot powerboat, he's quick to endorse it – if only for safety reasons.

"There has to be some accountability" on the water, says Mr. Cassano. "Like, you can risk losing your license."