IN PERIL, by Skip Strong and Twain Braden, The Lyons Press, 2003, 272 pages, hardcover, $22.95.

“Steve, how far from the shoal?” I yell into the chartroom.

“Eight-tenths of a mile,” comes the reply. We are running out of room. The Cherry Valley is just over a tenth of a mile long and we are only eight ship lengths from our drop-dead point.

The Cherry Valley is a 688-foot-long, single-hulled tanker with almost 10 million gallons of number-six oil on board. Tropical Storm Gordon is in the area. The seas are running in excess of 20 feet and the wind is blowing at 40 knots with gusts to 60. The rain is falling in blinding sheets. The ship is rolling 20 to 30 degrees with each wave. The “drop-dead” point is less than a thousand yards from the buoy marking Bethel Shoal off Fort Pierce, Fla.

Somewhere in the murk is a tugboat, with five men aboard, that is towing a large barge. The tug has lost both engines. It and the barge are being driven inexorably toward Bethel Shoal by the wind and seas at a speed of 21/2 knots (almost 3 mph). The Coast Guard asks the Cherry Valley to render any assistance possible. There is nobody else available and there is very little time.

Prentice “Skip” Strong III, a graduate of Maine Maritime Academy and resident of Southwest Harbor, is making only his second trip as a captain. He is 32 years old. Any aid that can be rendered is his decision and his alone.

If the Cherry Valley winds up on Bethel Shoal and spills her cargo, thereby coating the Florida beaches with oil, the Exxon Valdez will be forgotten and Skip Strong will replace its captain as “Environmental Enemy Number One.”

In normal operations, tankers are the vessels towed, not the vessel doing the towing. While the Cherry Valley is far smaller than a super tanker, it still takes a mile to stop from a speed of 10 knots and a mile and a half at 15 knots. It is propelled by a steam turbine that turns a single, 22-foot-diameter propeller (screw). It is a more complicated task to control a steam-powered ship in close quarters when rapid changes in power and direction are being requested by the captain. A steam power plant simply isn’t built for that.

More modern ships have electronically controlled diesel power plants that react to engine orders from the bridge almost instantaneously. Powerful, ocean-going tugs, in addition to diesel power plants, have twin screws that immeasurably increase the vessel’s handling ability. With twin screws, you can go back on one and ahead on the other, enabling the ship to turn in its own length. Strong has none of these advantages in the Cherry Valley as she slogs north along Florida’s east coast.

What follows is convincing proof that nonfiction can be equally as gripping as the best fiction. With time running out, Strong and his crew display award-winning (literally) seamanship and save not only the tug and its crew but the barge as well. The maritime heroics over, a problem of a distinctly different variety surfaces.

The barge is carrying a fuel cell, belonging to NASA, headed for Cape Canaveral and the space shuttle. It is valued at roughly 50 million dollars. Saving the tug and barge brings into play the ancient maritime tradition of salvage. This entitles the owners and the crew of the Cherry Valley to a reward equal to a portion of the value of the vessels and cargo they saved. Can you spell lawyer? Can you predict federal court?

To a sailor, the legal struggle isn’t quite as absorbing as getting a towline from a tanker to a tug in the middle of a blinding gale, but it’s not a bad second. Suffice to say, it is easy to tell the good guys from the bad guys. Guess who is working for the government?

Strong and his co-author, Twain Braden, have written a marvelous yarn about an incredible rescue. Along the way, they have sprinkled in enough facts about ships, their operation and their crews to assure that even the rankest landlubber doesn’t get left on the pier. They have also left no doubt that the Maine tradition of courage and excellence on the high seas is alive and well.