ISLIP, N.Y. (CBSNewYork) — Every year, hundreds of people are killed or injured in boating accidents on Memorial Day weekend.

On Long Island, police say they’ll take to the waters to track down drivers under the influence, but experts say that’s not the only threat on the waterways.

As CBS2’s Jessica Layton reported, thousands of boaters on Long Island’s South Shore were lining canals and docks Friday gearing up for their holiday plans on the water.

For educator Sammy Gergis, of Islip, getting his boat ready means checking to make sure everything is ready safety-wise for his guests when he takes the helm this weekend.

“Just being cognizant of all the surroundings and everyone that’s around me, to prevent any sort of accident, to minimize the risk,” he said.

And there is great risk. Last year, police recorded 14 boat accidents in the Great South Bay — one person was killed and five injured.

At the Bay Shore dock, police showed off the vessels they’ll use to watch for unsafe drivers, especially those under the influence.

Besides the county boats, Islip is adding its harbor boat and a dozen marine patrol officers. Police Commissioner Timothy Sini said intoxicated boaters should expect no mercy.

“If you make the decision to drink and drive, we will arrest you,” he said.

But operator error by sober captains is involved in half of all boating accidents. While Suffolk County mandates operators take a safety course, no license is required statewide.

George Fontaine, who teaches boat safety, pointed to the capsizing five years ago in Oyster Bay of a family boat in which three children died when the waters were overcrowded.

“There’s no brakes on a boat, OK,” Fontaine said. “So you don’t think you’re going to go out there and run along at 15 knots and then all of a sudden stop dead. You’re not going to do it.

Fontaine said the No. 1 safety mist for any holiday boater is to have plenty of life-saving flotation devices on boards.

Under the law, repeat offenders of unsafe boating face stiffer penalties than first-timers.