Completely against us, then. Unfortunate, that.
Move 3 ahead of the ship we're guarding. With the wind favouring the enemy, they'll be coming towards us quite quickly, so we'll want to get ahead to meet them. Both the barque and my own Nottingham should be maneuverable enough to get off a broadside and then turn around for a second, while a ship as big as that probably is not. Chain shot on both sides for me. Don't actually fire until they definitely hostile, though.
On a side note, how many squares away is the horizon?