Dirhavel (or Dirhaval) was of the house of Hador, and had probably fled from Dor-lomin when he came to the Havens of Sirion. Because of his ancestry he was very interested in the deeds of his house and searched for information among all the refugees. Thus he met Mablung of Doriath who told him many things about Turin Turambar. By luck he also met an old man called Andvir. He was a son of Androg who had been a member of Turin's outlaw-band.
He used the information he had gathered and wrote in Sindarin a very long, in fact the longest of all from that time, lay in the verse-mode called Minlamad thent/estent. This mode was spoken verse, not unlike the Old English alliterative mode. The Narn I Chin Hurin tells of the fates of Hurin's children Turin and Nienor, with emphasis on Turin. It is a very tragic story, but the lay was highly praised by the Elves and remembered by them. It is the only full account on Turin's life, and all later writings on the subject fall back on this one.
Unfortunately, Dirhavel was killed when the sons of Feanor finally attacked the Havens of Sirion in the third and last Kinslaying.
The meaning of the name is unknown. It seems to contain the elements dir "watch", el "star", but this is too uncertain to make any guessing.
•The History of Midde-earth vol. 11 Aelfwine and Dirhaval
•The Silmarillion Index