One small piece of advice to the original poster. DO NOT shoot the flare to windward! You may find it drifting back upon you!
I was running on fumes late at night coming into Morro Bay Ca. I was talking with Harbor Patrol to advise them of my situation. Not hardly a breath of wind on the bay. The Coasties jumped in, and were returning from a search. They asked me to shoot off a flare, and they would spot me 5 gallons of fuel.
I thanked them, and went down for the gun. Without thinking I shot it up into the direction of the Coasties. As it started to descend it began to drift back to me. I had both sails up seeking any wind at all. The flare drifted what what seemed like inches past the luff of my headsail......LESSON LEARNED