This intimate floating concert hall is, as usual, host to a variety of repertory this week. On April 18 the pianist Gilles Vonsattel's program is heavy on modern music by composers like Benjamin Shadow, Messiaen and Frederic Rzewski. (The Rzewski work, "Winnsboro Cotton Mill Blues," returns as part of the pianist Thomas Schultz's recital on April 23.) The barge's artistic director, the violinist Mark Peskanov, takes the stage on April 19 with the pianist Doris Stevenson and works by Bach, Schumann and others. The concert on April 20 will honor Herbert Stessin, a longtime piano faculty member at the Juilliard School who died in 2011, and feature the pianists Orli Shaham, Jonathan Feldman, Rita Sloan and Sakiko Ohashi.