A memorial service for Stephen Mitchell Hoyt, 27, a former Washington resident who was lost at sea on Sept. 23 off the coast of Rhode Island, will be held at 11 a.m. Wednesday in the Bethlehem Chapel of Washington Cathedral.

He was the son of Mary Finch Hoyt, press secretary to First Lady Rosalyn Carter.

As experienced seaman, Mr. Hoyt was captain of the 75-foot trawler, Lobsta I, which capsized 54 miles of Point Judith, R.I. Four other crew members, companions of longstanding, were also lost.

Mr. Hoyt was born in Pasadena, Calif. He came to Washington at the age of 7 with his parents, the late James Mitchell Hoyt Jr. and Mrs. Hoyt. He graduated from the Hawthorne School in 1970.

He became interested in fishing while attending Roger Williams College in Rhode Island, and for the last three years had commanded Lobster trawlers harboured at Point Judith. He and his crew were making their first trip on the "Lobsta I" when they disappeared. He was making arragements to invest in the ship as a part owner.

In addition to his mother, he is survived by his wife, Janet Wing Hoyt, of the home in Narragansett, R.I.; a brother, Thomas Wade Hoyt, of Sumner, Md., and his grandmother, Virginia P. Finch, of Pacific Grove, Calif.