From the wave washed level of a rubber raft or fisherman's rowboat, Lake Erie in rough weather might just as well be the Atlantic Ocean to the man who needs help in a hurry.  The water is just as wet, in some places just as deep. and it can be just as dangerous when a sudden squall lashes down out of Canada.     Wise men treat Erie with respect, but hundreds have been caught on it through engine trouble, or because they run out of gas or forget such essentials as oars or life-jackets.  Scores have vanished in its depths or frozen to death on tiny islets.     For decades, the alternatives often were sink or swim.  But in the past five years, fishermen and pleasure-craft owners have come to rely on Grosse Ile Naval Air Station's crack helicopter and crash-boat rescue squadron to seek them out in this watery wilderness.                                                                           "May Day"     Pilots too, know that the international distress signal of "May Day!" will bring quick help if they are forced to "ditch" their planes in the lake.  Last summer, for example, crew members of a Royal Canadian Air Force plane were saved by Lt. Cdr. Lou Helms - at night - when they fired rocket flares toward the sound of his rotors.     An Amherstburg, Ont., man who had been stranded on a windswept dike in the Livingstone Channel for two days after his boat drifted away was brought home to his grieving family.  Dozens of downriver-area fishermen have been picked up, chilled and famished, after being lost overnight in a storm.     Last January a woman and her son were air-lifted from a small island in the lower Detroit River, three days after her husband had drowned, by Cdr. Gene Mullkoff.  The woman and son swam ashore through ice floes, but were unable to summon help until mainland residents heard them clanging a ship's bell.     It renewed the squadron's determination to keep searching on every mission until all hope is exhausted.  Sometimes, tragically, the search is in vain.     Many of the regular squadron's seven pilots and four aircrew men, as well as 60 part-time reservists in two helicopter training units, are veterans of World War II, the Korean conflict and "life guard" duty at sea, where their job was to save downed fliers.     Grosse Ile" senior helicopter pilot, Lt. Cdr. Walter Staight, recently completed four years of such duty with the Pacific Fleet, in which he flew Walt Disney photographers while they filmed a movie.     Grosse Ile is equipped with three HUP-2 (helicopter utility.  Piasecki model) twin-rotor craft and a fast, trim crash boat for combined operations.  The latter often is used to tow in stranded sportsmen who are not in danger.     "Our whirly-birds may not be the most graceful aircraft compared to some of the sleek, new Navy jets," said Lt. Cdr. Cody Owen, Grosse Ile's public information officer, a helicopter pilot himself.  "But a plane zooming overhead at 500 miles an hour can't very well stop to help."     *Article for the May 11th 1958 Detroit News Pictorial Magazine