"Easy. We will make up our signal and then take the flags necessary to show it and conceal them where we can get them at any moment. Then when we sight a vessel we can bend them onto the halliards and have them aloft before anyone can interfere. It would be a minute or two before they could haul them down, even if they discovered them at once, and in that time it is likely that the other ship would have read them. Anyway, it is worth trying."