Performers who favor a "traditional" style do not necessarily believe they are replicating the exact style of shanty singing of the 19th century. However, within the constraints of modern contexts, they tend to adhere to certain stylistic traits that are believed to have characterized the genre historically. These may include a loud or full voice, an emphatic, strident—even harsh—tone (as if to carry over the noise of wind and waves), and tempos and rhythms that are reasonably conducive to working. They often perform "a capella" or only with light instrumentation typical of sailors (e.g. concertina). In general, performances may be more "rough around the edges" and be of variable length to accommodate impromptu changes in verses.