sentences:  Experiments with radio acoustic ranging, despite initial difficulties, demonstrated that the method also was practical, although difficulty with getting some of the explosive charges to detonate hampered some of the experimental program.In April 1924, the Coast and Geodetic Survey concluded that both echo sounding and radio acoustic ranging were fundamentally sound, with no foundational problems left to solve, and that all that remained necessary was continued development and refinement of both techniques during their operational use.Heck turned over continued development of echo sounding and radio acoustic ranging to "Guide"'s commanding officer, Commander Robert Luce, and returned to his duties in Washington, D.C.
  
  Operating off Oregon in 1924, "Guide" became the first ship to employ radio acoustic ranging operationally.