E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Fifth-rate men of war. Thus, in Howells letters we read, At the return of this fleet two of the whelps were cast away; and in the Travels of Sir W. Brereton we read, I went aboard one of the kings ships, called the ninth whelp, which is . 215 ton and tonnage in kings books. In Queen Elizabeths navy was a ship called Irons Whelp, and her navy was distinguished as first, second tenth whelp.