The Coast Guard (search) says millions of pleasure craft, fishing boats and ferries fall outside its security nets, hampering its ability to safeguard thousands of miles of coastline against terrorist attack.

"How do we include recreational boats — some 58 million in this country — into our security regime without infringing upon the liberty of boaters?" Admiral Thomas Collins (search), commandant of the Coast Guard, said Tuesday.

Boaters are proud people who "toot around on the water" and don't want the government to tell them where they can go, Collins said following an address at the U.S. Maritime Security Expo (search), a conference on protecting ports, harbors, ships and cargo against terrorists, thieves and other threats.

"But some of those yachts are big," he said, "and can hold lots of good stuff and bad stuff."

The Coast Guard has identified 50 areas in which the maritime system is vulnerable to a terrorist attack, Collins said. It is working on solutions to blend everyone's needs: to close the gaps and mitigate the risks while not impinging on boaters' rights or interfering with the flow of commerce.

Specific initiatives will be presented to President Bush as part of a National Maritime Security Plan (search).

Among the Coast Guard's targets are recreational boats, an estimated 110,000 fishing vessels, and ferries that carry tourists and commuters, Collins said.

"How do we screen for explosive devices on a ferry system that moves millions of people, particularly commuters, without constipating the whole system?" Collins asked.

Better technology for detection of explosives on ferries and cargo ships is needed, he said.

"Right now the most capable technology we have," Collins said, "is dogs."

At least 95 percent of the goods coming into the country arrive on ships, according to Collins, and cargo security is crucial.

But Collins said he believes it is "illogical" to screen each cargo container, and inspecting millions of containers would be impossible.

"The issue is inspecting the right one," he said.

That goal can be reached by targeting those ships that have been identified through intelligence reports as having anomalies in the crews, cargo or containers, he said.

"You want to inspect the highest risk," he said, "not every ship that comes into our port."