I really like the new flares and enjoy firing them off whenever I can find the slightest reason.
I thought it would be interesting if there was some sort of game event that created particularly dark seas at night so that flares would be necessary for safe navigation. Perhaps a lunar eclipse or some sort of majic curse.
Additionally I like firing them off when I see a ship approaching if I am doing a voyage and don't want any trouble. I have no idea how other ships perceive this warning shot though. I also shoot fireworks if the other ship does not seem aggressive as a way to say hello.
How about everyone else, is there any message you intend for other crews by firing a flare or fireworks?
If you were on the prowl and a target ship fired a flare would you heed the warning?
