The days when Yachtmasters had to learn all the signal flags and Morse code are mercifully long past. However, recognising one or two signals remains a useful safety factor. The ‘T’ flag looks like a French ensign with the colours back to front. It means that the vessel flying it is engaged in pair trawling. Somewhere away on her beam will be her partner, and the consequences of finding yourself between them don’t bear thinking about. You won’t see pair trawling often – the practice is banned in UK waters – but continental fishing boats really do show this flag even though you might feel their lights sometimes leave much to be desired.