Question about convoys' navigation at night

CaptBones · 12-14-19, 01:20 PM

...but, to answer the question...no, not really.

Mostly cloudy or overcast skies generally don't make much difference. Yes, starlight and moonlight are filtered or blocked almost completely. However, there is still a distinct difference along the line of the horizon (provided you have decent "night vision" to begin with). In fact, clouds beyond the horizon will often help you to see the shape of a vessel that is on or just beyond the horizon (hull down). Unless you're looking at/for a small silhouette or shadow (like a surfaced U-Boat) at close range, you can readily make out the shape/shadow of a vessel at a good distance.

The hard part is seeing those small shapes at close range. When you're looking "down", those tend to merge with the darkness of the water. But, they also tend to produce waves/foam along their waterlines, provided they are moving at more than a crawl. That will give them away...unless the seas are a little rough and wave action is producing whitecaps and some foam, which it almost always is. It is often the case that lookouts in small vessels can spot things on the surface at night more easily than lookouts in large vessels. They are down closer to the surface and the line of the horizon is closer, paradoxically meaning they can see shapes and shadows farther away. One of the "tricks of the trade" for night operation in blackout conditions is to put extra lookouts down on the lowest weather deck...young kids with good night vision come in very handy.

Fog is the real problem at night...during the day as well, of course. It eliminates the horizon and shrouds even the largest ships (not to mention rocks, reefs, buoys, lighthouses, and everything else out there). In foggy conditions, sound becomes much more important than sight for "seeing" things. Sound carries over long distances in fog and can reveal the presence of a vessel miles away. That's when young kids with good hearing come in very handy.

12-14-19, 01:20 PM	#7
CaptBones The Old Man Join Date: Nov 2010 Location: Rockton, IL Posts: 281 Downloads: 208 Uploads: 0	You're very welcome... ...but, to answer the question...no, not really. Mostly cloudy or overcast skies generally don't make much difference. Yes, starlight and moonlight are filtered or blocked almost completely. However, there is still a distinct difference along the line of the horizon (provided you have decent "night vision" to begin with). In fact, clouds beyond the horizon will often help you to see the shape of a vessel that is on or just beyond the horizon (hull down). Unless you're looking at/for a small silhouette or shadow (like a surfaced U-Boat) at close range, you can readily make out the shape/shadow of a vessel at a good distance. The hard part is seeing those small shapes at close range. When you're looking "down", those tend to merge with the darkness of the water. But, they also tend to produce waves/foam along their waterlines, provided they are moving at more than a crawl. That will give them away...unless the seas are a little rough and wave action is producing whitecaps and some foam, which it almost always is. It is often the case that lookouts in small vessels can spot things on the surface at night more easily than lookouts in large vessels. They are down closer to the surface and the line of the horizon is closer, paradoxically meaning they can see shapes and shadows farther away. One of the "tricks of the trade" for night operation in blackout conditions is to put extra lookouts down on the lowest weather deck...young kids with good night vision come in very handy. Fog is the real problem at night...during the day as well, of course. It eliminates the horizon and shrouds even the largest ships (not to mention rocks, reefs, buoys, lighthouses, and everything else out there). In foggy conditions, sound becomes much more important than sight for "seeing" things. Sound carries over long distances in fog and can reveal the presence of a vessel miles away. That's when young kids with good hearing come in very handy.