A traditional term in the British Navy meaning to serve out an additional tot of grog to a ship's crew. The main brace itself was a purchase attached to the main lower yard of a square-rigged ship to brace the yard round to the wind. However, it probably has little to do with the saying beyond the fact that hauling on the main brace called for a maximum effort by the crew. In the days of sail the main brace was spliced (in terms of drink) in very bad weather or after a period of severe exertion by the crew, more as a pick-me-up than for any other purpose. But with the introduction of steam propulsion, with machines to take most of the harder labour out of seagoing, the main brace was spliced only on occasions of celebration or, occasionally, after battle. Now that rum is no longer issued aboard ship, splicing the main brace is a thing of the past.
A small tap used to empty contents from a barrel containing rum or whisky aboard ships.
Brass spigot or tap used for inserting into a barrel containing liquid such as rum, whisky or vinegar etc