"My horse saved me over the last fence," was the way Rodney Jenkins explained his victory aboard Second Balcony in the Eisenhower Trophy competition at the Washington International Horse Show at Capital Centre last night.

The 9-year-old gelding, owned by Edie Spruance, toured the course in 29.79 seconds to edge Melanie Smith on Calypso by less than two seconds in the two-horse jumpoff against time before a crowd of almost 3,500.

Second Balcony and Calypso were the two survivors of a world class field of 27 jumpers that started the Eisenhower competition during the afternoon. Designer Steve Stephens' twisting layout, with a combination of difficult doubles and trebles, had eliminated 12 before the evening session began.

France's Faolo d'Escla and two open jumpers, Hole in One and Quick Draw, were added to the night's opening round but were quickly eliminated. Calypso, a winner of three Grand Prix this year, including the Upperville Virginia classic, went clean and was followed by Second Balcony, also faultness.

The next 14 entries fell victim to the course, several at the triple combination. Eight managed to survive with only four faults and tied for third place, but sat on the sidelines as Smith and Jenkins came back for the jumpoff.

Smith went first and Calypso, a 10-year-old Dutch bred, racked the first fence, tapped the second, made a brilliant cut into the third and went clean over the final three obstacles in 31.72.

Jenkins, who has won more Washington International jumping classes than any competitor and won the Eisenhower on Idle Dice in 1971, took Second Balcony over the first cleanly, tapped the second and third and was clean over the fourth and fifth before rolling over the final.

"We made a tighter turn going into the last fence than I thought," said Jenkins. But the bar held.

Tonight's program will open with the Ben O'Meara Memorial Challenge Trophy at 7:30. The Driving Championship, exhibitions by the Budweiser hitch and the Black Stallion precede one of the premier events of the show, the Prix des Nation.