Jimmy Buffett and Jesse Winchester took an unexpected turn off the Beltway on the way to Townson State College yesterday and their resultant free concert at American University made the afternoon for a relaxed campus audience.

Winchester, whose personal story of draft resistance and night-clubbing in Canada is now firmly entrenched in the rock 'n' roll tradition, managed to impress despite some built-in disadvantages.

Winchester is naturally languid, and outdoors, where intimacy is sacrificed for atmosphere, his style of vocalizing can appear a bit lame. Also, his celebrity aura may have waned recently through overexposure. Still, Winchester and his all-Canadian "Midnight "Let the Rough Side Drag" and "Rhumba Man" and both "Yankee Lady" and "Nothing But a Breeze" were precise and moving. The latter two demonstrated that despite his years north of the border Winchester's music is rooted in the American South.

The development of Jimmy Buffett as an artist is directly related to the evolution of his Coral Reefer Band into a first-class musical unit.

Yesterday, pianist Jay Spell turned "Banana Republics" into an exhibition of tangy flourishes and Greg "Fingers" Taylor's mournful harmonica accented "A Pirate Looks at Forty" and "Tampico Trauma."

Buffett, as usual, was loose and enjoyable and he seemed to bring out the sunshine on cue. You couldn't have cast a better lead for a pleasing afternoon on the grass.