Also spelled weather gauge
The weather gage refers to how two ships are positioned relative to each other in relation to the direction of the wind. The biggest application of this tactic came during the age of sail when battles were often decided by how well vessels could use the wind to the best of their advantage. To have (or hold) the weather gage is to be positioned to the windward side of another vessel. As with any naval tactic, there are advantages and disadvantages to holding the weather gage.

Advantages
The biggest advantage for a vessel on the windward side is that it can often dictate an engagement, as well as the time and place of attack. A ship holding the weather gage can easily move downwind towards its enemy at its own pace, thus controlling its range and position to the enemy. Since the vessels may be heeling over due to the wind, this position was also advantageous for allowing the guns to fire into the enemy’s exposed hull which was a favored target by the British. The direction of the wind also means that any smoke from the guns of the windward ship is blown away from them and towards the enemy, limiting their visibility (Grant, 2008, p. 159). It’s also easier for ships to windward to see signal flags hoisted by the flagship or repeated by the frigates in a battle line since the smoke from the guns is blowing away from them. The windward position gives a fleet a further advantage of making it easier for the van or rear to double the enemy line. Fireships, when they were used, could also be employed by the windward side (Kemp, 1988, p. 485).
For the vessel on the leeward side, their main advantage is that the wind allows them to easily withdraw from the fight. Since moving downwind is far easier than moving upwind, the ships on the leeward side of the battle can simply turn and sail away from their aggressor. The heeling of the leeward ship also makes it easier for them to fire more of their guns into the rigging and sails of the windward ship. The idea was to destroy the windward ship’s method of propulsion (Grant, 2008, p. 159). Any damaged or disabled ships may slowly drift from the windward to the leeward side, thus allowing them to be captured. A damaged or disabled ship on the leeward side of the engagement could also easily bear away from the fighting. While the windward force could technically control the engagement, the leeward force could be at an advantage to force the engagement if the windward side didn’t want to fight (Kemp, 1988, p. 485 – 486).
Disadvantages
A potential disadvantage of holding the weather gage is that it commits a vessel to combat and they have poor options to disengage from battle should they need to. The windward vessel could also find itself in a position where fewer of its guns are available for use on the engaged side if the seas flow into the lower gun ports due to the vessel heeling over too far (Grant, 2008, p. 159).
For the ship on the leeward side of the fight, the obvious disadvantage is that they can’t dictate the pace or range of battle. They also risk being raked across the stern if they disengage and turn away from the fight (Grant, 2008, p. 159).
The Battle of Cape St. Vincent (February 1797) – It doesn’t always matter
Historically, the British Royal Navy famously favored attacking from the weather gage. They would approach their opponents and aggressively bear down on them (Grant, 2008, p. 159). That being said, having the weather gage didn’t always ensure victory.
Richard O’Neill (2003) writes that during the Battle of Cape St. Vincent on 14 February 1797, the Spanish held the weather gage and the British fought defensively from the leeward side (p. 122). On the morning of the 14th, the British frigates had sighted the Spanish in two main groups to windward. Whereas the British, under Admiral Sir John Jervis, were quick to form a battle line, the two groups of Spanish ships, under Admiral Juan de Cordova, struggled to get into position when he ordered them to form a battle line. Though the Spanish held the weather gage, the difficulty that they had in forming a battle line saw them break into three groups. Admiral Jervis led his battle line around to attack the largest group of Spanish ships that were approaching the rear of the British line and could’ve potentially crossed them at the stern before fleeing for Cadiz. However, Commodore Horatio Nelson, aboard the Captain and third from the rear of the British line, saw what the Spanish were trying to do and broke formation to engage the Spanish flagship, Santisima Trinidad. The ships behind Nelson saw what he was doing and turned to follow him. Ultimately, Nelson successfully captured the San Nicholas and San Josef in what became known as, “Nelson’s patent bridge for boarding enemy vessels.” While the Santisima Trinidad briefly struck her colors to surrender, she escaped after further Spanish assistance arrived. The remaining Spanish fleet, badly damaged, fled to the port of Cadiz, where they were eventually blockaded in by the British. While the Spanish began the battle with more powerful ships and the advantage of holding the weather gage, they were defeated by the better-trained Royal Navy. The British made good use of intelligence, used frigates as scouts, and established supremacy over the Spanish by allowing aggressive action by individual captains once the melee began (O’Neill, 2003, p. 124 – 127). Thus, despite being upwind at the start and possessing a numerical advantage in both ships and firepower over the British, the Spanish fleet was hampered by inexperienced crews, poor training, and poor morale. The British compensated for their initial disadvantage in position by having far more aggressive leadership, cohesive doctrine, and motivated crews.
Of course, there are certainly many examples of naval battles where the weather gage was a (significant) factor in the victory. The above is merely one example where it wasn’t. It’s important to remember that good leadership, thorough training, clear communication, reliable intelligence, and flexible battle plans that allowed captains to take the initiative were far more conducive to achieving victory than any single tactic.
Modern Times
The use of the weather gage obviously isn’t a major factor in naval battles anymore. However, wind direction still does factor into naval operations, particularly when it comes to aviation. Specifically, aircraft carriers need to turn into the wind and increase speed to increase the apparent wind over the deck when launching and recovering aircraft. This could potentially put them in a position where they’re vulnerable to attack.
References
Grant, R.G. (Eds.). (2008). Battle at Sea: 3,000 Years of Naval Warfare. D.K.
Kemp, P. (Eds.). (1988). The Oxford Companion to Ships and the Sea. Oxford University Press.
O’Neill, R. (Eds.). (2003). Patrick O’Brian’s Navy: The Illustrated Companion to Jack Aubrey’s World. Salamander Books.