'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.
It is very uncommon in heraldry. The anchor is the emblem of salvation and hope. It is also an appropriate device for the coat of arms of a family with a seafaring tradition. It is a common figure in the English armour, which is not surprising given that Britain is an island. It was even a device that was once born by King Richard I.