SUBSIM Radio Room Forums - View Single Post - Question about convoys' navigation at night

CaptBones · 12-09-19, 01:26 PM

Having spent most of a 30-year Navy career at sea, I've steamed in formation without lights quite a few times; in company with aircraft carriers, cruisers and even battleships. Even in the deadest darkness of night, at distances of 500-1000 and usually out to several miles, the shape/shadow of a ship is very noticeable. An experienced seaman can make out a vessel and with fairly good accuracy, determine its AOB/heading and even the approximate speed. Most importantly, you can judge the relative movement of even a darkened vessel at several miles ("CBDR" is that red flag that you want to avoid..."constant bearing, decreasing range").

To be sure, merchant ship Captains (Masters) as well as their First and Second officers are generally more than just a little bit experienced. Most of those who sailed in convoys in WWII were genuine "Old Salts" and would have little trouble keeping station in all but the worst weather conditions. In those conditions, the convoys would be dispersed precisely because station keeping would be impossible, even with navigation lights and those lights turned the ships into big, fat targets. But then, dispersing a convoy was also asking for trouble; trying to get out of that collection of ships, all of which were also trying to get away, was itself an invitation to potential collisions all around. There were also collisions due to other factors; propulsion/steering breakdowns and the like, or just inattention or confusion by bridge watch personnel.

The dimmed white stern light was adequate for assisting ships to maintain station in convoy under most circumstances...follow the leader, but no too close. The lead ship in each column had to keep station on the other column leaders, 90 degrees to port and/or starboard and at the desired distance. Even at 500-1000 yards at night, determining distance with a stadimeter is usually not that difficult. However, contrary to the idea that the dimmed stern lights were helpful in foggy conditions, in anything more than just a very light fog, a dimmed white light in fog is almost useless.

12-09-19, 01:26 PM	#4
CaptBones The Old Man Join Date: Nov 2010 Location: Rockton, IL Posts: 281 Downloads: 208 Uploads: 0	Collisions did happen. Having spent most of a 30-year Navy career at sea, I've steamed in formation without lights quite a few times; in company with aircraft carriers, cruisers and even battleships. Even in the deadest darkness of night, at distances of 500-1000 and usually out to several miles, the shape/shadow of a ship is very noticeable. An experienced seaman can make out a vessel and with fairly good accuracy, determine its AOB/heading and even the approximate speed. Most importantly, you can judge the relative movement of even a darkened vessel at several miles ("CBDR" is that red flag that you want to avoid..."constant bearing, decreasing range"). To be sure, merchant ship Captains (Masters) as well as their First and Second officers are generally more than just a little bit experienced. Most of those who sailed in convoys in WWII were genuine "Old Salts" and would have little trouble keeping station in all but the worst weather conditions. In those conditions, the convoys would be dispersed precisely because station keeping would be impossible, even with navigation lights and those lights turned the ships into big, fat targets. But then, dispersing a convoy was also asking for trouble; trying to get out of that collection of ships, all of which were also trying to get away, was itself an invitation to potential collisions all around. There were also collisions due to other factors; propulsion/steering breakdowns and the like, or just inattention or confusion by bridge watch personnel. The dimmed white stern light was adequate for assisting ships to maintain station in convoy under most circumstances...follow the leader, but no too close. The lead ship in each column had to keep station on the other column leaders, 90 degrees to port and/or starboard and at the desired distance. Even at 500-1000 yards at night, determining distance with a stadimeter is usually not that difficult. However, contrary to the idea that the dimmed stern lights were helpful in foggy conditions, in anything more than just a very light fog, a dimmed white light in fog is almost useless.