'MUA', All Acronyms, 13 January 2018, <http://www.allacronyms.com/_Medical/MUA/Medical> [accessed 13 January 2018] Bluebook All Acronyms, MUA (Jan. 13, 2018, 7:01 PM), available at http://www.allacronyms.com/_Medical/MUA/Medical. CSE All Acronyms. MUA [Internet]; January 13, 2018 [cited 2018 JAN 13]. Available from: http://www.allacronyms.com/_Medical/MUA/Medical.
A sea anchor is deployed off the bow and a drogue is deployed off the stern. The sea anchor keeps the bow up to weather, a drogue is usually smaller, and allows you to move downwind while acting as a brake. Each has wide variations in the sizes used, and this affects their specific role in sea survival.
Well first of all it's not an anchor. It isn't used to hold your boat in one position or tie it to the bottom. It is a device that you trail off the back end of the boat while at sea. It helps keep the boat pointed into the waves or wind, after you've taken the sails down.