Hence prob. chock adv. (XVIII) close (up) to, and in chock-a-block (i) naut., said of a tackle with the two blocks run close together, (ii) gen., crammed close together.
"chock-full." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. (September 18, 2018). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/chock-full
"chock-full." The Concise Oxford Dictionary of English Etymology. . Retrieved September 18, 2018 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/chock-full