One of the more interesting oceanographical phenomena of recent years is that Bermuda has been moving closer and closer to the mainland.

It is now well within range of family cruising boats, 25-foot midget ocean racers, formerly experimental multi-hull yachts and shorthanded versions of all of the ahove.

The Onion Patch, as the island is never called anymore come to think of it, is still 640 miles from Newport, R.I. What has changed are the sailors and their boats.

The classic Bermuda race is still held every other year and is the premier event of East Coast yachting. It is a race for big boats, big crews and big checkbooks. You and your boat have to be invited, too.

This is an Annapolis-to-Newport race year -- it will start June 16 -- and that used to mean there'd be no Bermuda race. In fact, there are no fewer than five races to the island this spring, each serving a special category of competitor. For the first time, one will start at Annapolis.

The senior of these newcomer events is the multihull Bermuda race, now in its 12th year, for trimarans and catamarans.

For aficionados of do-it-yourself sailing, the Bermuda One-Two will depart Newport June 9, the same day as the multihulls. The One-Two is a single-handed race to St. Georges, with a double-handed (two-person) return.

The cruising fraternity, eschewing spinnakers and rule-beater hulls, will start its race from Marian, Mass., and encourage family crews. For southern-based yachts Newport is a long passage away, so a Daytona, Fla.-to-Bermuda contest will be inaugurated it May.

The Chesapeake gets into the act this year because Roger Bartholomee of Baltimore, who is rear commodore of MORC, Station 15, couldn't quite find a Bermuda race that fit.

Bartholomee sails a CS-27, and wanted to enter the Marian cruising race in 1977. His boat was too small, so he signed up for the Bermuda One-Two instead. After the solo voyage to Bermuda, and the return race with his wife Earlyn, he made two decisions: "That single-handling wasn't my bag, and that there really ought to be a race to the island from the Chesapeake."

So June 9, while multihullers and One-Twoers start from Newport, Batholomee expects between six and 10 MORC boats to depart Annapolis for the same destination. Since the distance between the mainland and Bermuda has shrunk, so has the size of the boats.

MORC stands for Midget Ocean Racing Club, and its members feel that good seamanship and good equipment make a good 25-footer as logical an offshore choice as any gold-plated 10-halyard syndicate yacht. Ever since Partick Ellam and Colin Mudie boggled the big-boat world by sailing a 19 1/2-foot dinghy transatlantic in the early 1950s, MORC folks have been on fire to cross the Gulf Stream.

Bartholomee says that his Bermuda race has no strict length requirements, and that entries are expected to be strong, miedium-displacement boats, such as those already signed up for MORC's 360-mile Great Ocean Race, a circumnavigation of the Delmarva peninsula that starts Thursday evening, May 24.

Some midgets, however, are smaller than others. What happens if somebody shows up with a minitonner?

"Well, I hope we don't have to face the problem," Bartholomee said. "But if somebody is crazy enough, say, to enter with a Creekmore 22, I would probably get some other opinions. I tend to be a little conservative... but not as conservative as some people. When you come right down to it, size is not as important as design and construction."

The MORC race is timed so that contestants can race back to Newport with the double-handed leg of the One-Two. More information is available from Roger Bartholomee, 1000 Woodsdale Road, Baltimore, Md. 21228.

Midget racers undoubtedly will catch guff from old hands who observe that the North Atlantic does not always have a sense of humor, and that the lessons of offshore passage-making are enforced with serious punishment.

Few groups of sailors have been more fully instructed in these matters than the multihullers, who this year expect to have their largest fleet, perhaps 20 boats.

Trimaran and catamaran design has come a long way the past decade, mostly from lessons learned rasing in Australia, on the West Coast and in the Atlantic. The early designs of Arthur Piver -- innovative in concept, cheap to build, roomy inside -- are now viewed with amused horror, like ugly ducklings offering a same of Russian roulette.

In the early years of the multihull Bermuda race half the fleet looked as if it couldn't make it, and sometimes it didn't. Boats broke because they weren't strong enough; they leaked because their hatches weren't designed right, and their rudders fell off during 18-knot bursts of speed. Some were too heavy, some too light, some had centerboards, some had keels, some had neither. Owners didn't seem to know how to sail them and de-designers seemed to rush back to their drawing boards after every race to undo their mistakes.