I AM THINKING of spending the rest of my life plying the waters of the Chesapeake Bay on the Teresa Ann, the neat little excursion boat that makes the round trip daily between Reedvile, Va., and Smith Island, Md. I want a lifetime pass so I can spend my days lying lazily on the deck and studying the gulls overhead while we breast the waves at an unhurried 10 mph. I want forever to be suspended between two worlds, cut loose from real life, aboard this classy white beauty with its engine chugging comfortably and the crabbers waving as they zoom by.

Like the migratory birds, the Teresa Ann will be gone when the winds blow sharp in October, heading south for her other life on the west coast of Florida. But right now she's offering daily an escape from life on the mainland, 10 a.m. to 4:15 p.m., and there could hardly be a nicer way to spend a summer's day. At precisely 10 every day, Capt. Gordon Evans, son of skipjack captain and former first mate on the shipjack Ruby Ford, pulls a blast on the hoarse-throated ship whistle and she's off to explode the island charted in 1657 by Capt. John Smith.

The Teresa Ann is named after Capt. Evans' pretty daughter, whose picture hangs prominently in the pilot house among the inspection documents required by the government. Teresa was two weeks old before her father first eyes on her, a measure of the press of the waterman's life when the crabs run. Cold dawns aboard the Ruby Ford and the long dull winters on Smith Island before the coming of electricity convinced Gordon Evans that there must be an easier way to earn a living. Now he wears a natty white uniform and a permanent tan, dividing his life between Ft. Myer, Fla., and Reedville, Va., a man at peace with his soul.

Evans is not an uncommon name on Smith Island. Nearly all the 650 inhabitants are named Evans, Bradshaw or Tyler, a circumstance which makes nicknames almost mandatory. Everybody makes a living from the sea, though there is more grumbling than there once was about the hardships of the life.

In spite of its isolation, for better or worse, the island is moving slowly into the 20th century. The last skipjack was sold last summer and telephone poles now march across the marshy terrain. High school students who once left home Monday and stayed the entire school week at Crisfield, now travel by school boat to the mainland, returning nightly. The new sewage plant is the island's proudest boast.

Capt. Evans' passengers find other things more intriguing. The Teresa Ann maks the circuit of the island to tour the Glen L. Martin National Wildlife Refuge, where anyone with binoculars can spot egrets and a variety of birds forever safe from the hunters' guns. As the boat picks its way through the tumbledown crab shacks, Evans who was born on the island, paints a thumbnail sketch of life on this archipelago.

You learn of the problems of a line minister tyring rantically to serve three churches on a Sunday, about the hodlings pens in which "peeler" crabs molt their shells, and a bit aobut how it was to grow up in the brown frame house by the docks where he lived much of his life. Steaming at last into Rhodes Point, he gives a blast on the ship's horn to warn the Bayside Restaurant it's time to put the soup on.

You walk straight down the gangplank almost to the front door of the Bayside, where for $8 the lunch courses keep coming till you cry for mercy. The Bayside, one of three island restaurants, is clean and attractive, and the crab soup which is the lunch opener is faultless. Everything is family style so you get to know your fellow passengers while handing on heaping dishes of clam fritters, ham, crab cakes, cole slaw, macaroni salad, green beans and pie. Soft shell crabs (being high even on Smith Island) are not on the menu, but if you're lucky and they have some on hand, you can order them a la carte. In June, an order was $3 extra.

After lunch, Betty Jo Tyler, the 17-year-old daughter of the restaurant owner, loads everybody into the Smith Island elementary school bus parked nearby on the oyster shell turnabout and gives a tour of the island. Don't think of missing it.

What you get to see through the bus window is a complex of canals, inlets and waerways of all kinds, the whole so flat that the tide barely manages not to wash over everything. Between the three major settlements grow acres of marsh grass and a few struggling trees, and near Rhodes Point by the side of the road stands one of the most impressive auto graveyards you are ever apt to encounter. Smith Islanders have a loose relationship with their cars, importing them from the mainland when they are already on their last legs and driving them until they will go no farther. The last mile is the one to the dump, where the owners simply get out and walk away, leaving the cars to rust away in the salt spray. License plates are considered unnecessary. Everybody knows who everybody else is, so why bother?

"yall these junk cars, they've been piling up here for years," says Betty Jo, driving poast with her pretty nose in the air. "Some trash compacter people came here a while back and we're just hoping they'll be back."

Other points of interest on the tour include the library, which nobody used so it was turned into the office of the semi-monthly visiting dentist. Farther on is the nurse's house, empty since the nurse got a better job offer on the mainland. "Lord knows who we'll get next," says Betty Jo philosophically, shifting gears. "There's no doctor." On to Aunt Livy's general store where Aunt Livy at 96 puts in a daily eight hours.

Capt. Evans has no competition from Reedville, but the Island Belle, under the command of Capt. Frank Dise, carries mail and frieght to Smith Island from Crisfield, delivering empty crab boxes to crab shanties along the way. Capt. Dise is well known for his ringiong renditions of Methodist hymns, offered up as he shifts his boxes among the shanties. Betty Jo searched for him to introduce him to her passenges as we lumbered through the settlements, but he was not to be found.

The Chesapeake can get rough in an excursion boat. Going over, the chair on which I sat in the pilot house came alarmingly close to tipping over and all of us made our way hand-over-hand along the railing. Going back a shift of wind smoothed the choppy waves to a placid sea, encouraging us all to leave the shelter of the afterdeck and sunbathe in the bow. The trip takes an hour and 45 minutes, mainly because Capt. Evans holds her head into the wind to avoid the worst of the buffeting.

Everything has its drawbacks, and the cruise on the Teresa Ann's difficulty is the starting time of 10 a.m. Since Reedville is 150 miles from Washington, the three-hour drive under pressure of not missing the boat is not relaxing. To avoid this, we left Washington Friday and spent the night at Windmill Point Marine Resort about half an hour south of Reedville on a promontory jutting into the Bay.

Windmill Point is a favorite port of call for pleasure boats working the bay and looking for a slip for the night and a ship's store to stock up.

It's a bit pricey -- $40 for two at the motel -- but our room was right on a sandy beach by the water, large and pleasant. We arrived late Friday night and were given the key and a map of the complex which proved so inadequate that after 15 minutes we had to return to the office to complain and demand an escort. This gave an initial bad impression, but a glance out our sliding glass door in the morning made us forget all about it. You can get a nice breakfast overlooking the yacht slip early enough to allow plenty of time to arrive in Reedville for sailing.

Rte. 3, which leads you to these watery delights, is a pretty, hilly, mostly two-lane strip bordered by nice countryside and an unusual number of picturesque rural churches. The air coming in the car windows is sweet with honeysuckle, and trumpet vine and field flowers brighten the ditches. Jelly fish have arrived in the bay, spreading their umbrellas everywhere along the shore, so watch it if you use the beaches at Windmill Point.

Reservations are essential for everything. The Teresa Ann charges $14 for the round trip; children 3-12, $7. Call 813-549-2484. Windmill Point has a toll-free line from Virginia -- 1-800-552-3743. The rest of us must call 804-435-1166.