CT-Rich
Contributor
Seems to me that you should take a surface bearing before dive and swimming the reverse on the on the way back. If visibility 50-100 feet a beacon on the anchor line will get you good enough. If this is a dead reckoning situation, you could plan out how far you were out were swimming on the original heading and have pre-plotted return headings based how you far you swim left (a bearing of 270) of your original course. Prior planning prevents poor performances. If you are running some sort of search and we are only talking a few hundred feet, with no obstructions (like a sand bottom) you might try running a line and then your return vector is based on winding in the line. Math skills are supposed to deteriorate before you become aware of narcosis, so trying to calculate a return vector will be hard unless you do the math topside.