What do the circles mean?

ETR3(SS) · 04-29-17, 12:15 PM

From what I remember from my lookout training, it was 14k yds(7 nm) to the horizon but that also depends upon the observers height as well. As for the various circles, you're on the right track. The 1/2 circle is the coverage area of the units active sonar, the 3/4 circle is the passive sonar envelope. The next two full circles are for visual and radar, with radar having greater distance than visual.

CaptBones · 04-29-17, 02:02 PM

IIRC the "3/4" circle for passive sonar/hydrophone is (should be) more like 330 degrees...all-around except for the baffles, 15 degrees either side of dead astern....in game or real world.

You "hit the curvature of the earth" right at the point where you're standing; the distance to the horizon depends on your height of eye. If you're bobbing around in a life jacket or on a raft, the distance to the horizon is a mile or less.

An observer's height of eye of 36ft provides for distance to the horizon of 7nm; that's about correct for a lookout in the shears of a fully surfaced USN "Fleet Boat" (or on the sail of a surfaced "boomer").

To get distance to the horizon of 14nm requires a height of eye of almost 145ft. But, you should also account for the height of the object you are looking for...consider that to be the height of eye looking back at you. So, a lookout with height of eye of 36ft should be able to sight an object that is also 36ft above the surface, at a distance of 14nm (provided it's large enough to be seen at that distance to begin with).

A good lookout, well trained and experienced, should be able to pick out the masthead of a ship well over the horizon. Of course, smoke can be a dead giveaway from an even much farther distance over the horizon.

Sniper297 · 04-29-17, 08:52 PM

This is an FAQ, so I made a new picture;

The outer ring has nothing to do with radar, it's the average distance a lookout will see something the size of a surfaced submarine. Sometimes they'll see you further away, sometimes you can get in closer than the max circle, it depends on a variety of factors. Seeing a big ship on the horizon is a lot easier than seeing smaller ships and boats, that's why the outer ring doesn't go all the way to the horizon - a WWII sub was a boat, a small target difficult to see more than 4 to 5 miles away.

The red half circle is the area where the sonar "pings" have a good chance of reflecting from a submerged sub strong enough to be detected. The yellow "3/4" circle is just listening for propeller cavitations and other noises like machinery and loading torpedoes, which is why there's a "SILENT RUNNING" option. Depending on how good the crew is, how fast you're going, how deep you are, and how far from the center of the circle you are, they might or might not hear you inside that semicircle.

The reason for the cutout at the back is "baffles", sound interference from the ships own machinery and propeller noise.

getbac · 04-30-17, 02:02 AM

very helpful......... the berbster told me the outer ring was visual but I could not understand it until now ...

getbac · 04-30-17, 02:24 AM

Quote:

Originally Posted by Sniper297

This is an FAQ, so I made a new picture;

The outer ring has nothing to do with radar, it's the average distance a lookout will see something the size of a surfaced submarine. Sometimes they'll see you further away, sometimes you can get in closer than the max circle, it depends on a variety of factors. Seeing a big ship on the horizon is a lot easier than seeing smaller ships and boats, that's why the outer ring doesn't go all the way to the horizon - a WWII sub was a boat, a small target difficult to see more than 4 to 5 miles away.

The red half circle is the area where the sonar "pings" have a good chance of reflecting from a submerged sub strong enough to be detected. The yellow "3/4" circle is just listening for propeller cavitations and other noises like machinery and loading torpedoes, which is why there's a "SILENT RUNNING" option. Depending on how good the crew is, how fast you're going, how deep you are, and how far from the center of the circle you are, they might or might not hear you inside that semicircle.

The reason for the cutout at the back is "baffles", sound interference from the ships own machinery and propeller noise.

WAY AWSOME.... copy/paste as we speak... thanx

04-29-17, 12:15 PM	#1
ETR3(SS) Ocean Warrior Join Date: Dec 2007 Location: Between test depth and periscope depth Posts: 3,021 Downloads: 175 Uploads: 16	From what I remember from my lookout training, it was 14k yds(7 nm) to the horizon but that also depends upon the observers height as well. As for the various circles, you're on the right track. The 1/2 circle is the coverage area of the units active sonar, the 3/4 circle is the passive sonar envelope. The next two full circles are for visual and radar, with radar having greater distance than visual. __________________ USS Kentucky SSBN 737 (G) Comms Div 2003-2006 Qualified 19 November 03 Yes I was really on a submarine.

04-29-17, 02:02 PM	#2
CaptBones The Old Man Join Date: Nov 2010 Location: Rockton, IL Posts: 281 Downloads: 208 Uploads: 0	That's right... IIRC the "3/4" circle for passive sonar/hydrophone is (should be) more like 330 degrees...all-around except for the baffles, 15 degrees either side of dead astern....in game or real world. You "hit the curvature of the earth" right at the point where you're standing; the distance to the horizon depends on your height of eye. If you're bobbing around in a life jacket or on a raft, the distance to the horizon is a mile or less. An observer's height of eye of 36ft provides for distance to the horizon of 7nm; that's about correct for a lookout in the shears of a fully surfaced USN "Fleet Boat" (or on the sail of a surfaced "boomer"). To get distance to the horizon of 14nm requires a height of eye of almost 145ft. But, you should also account for the height of the object you are looking for...consider that to be the height of eye looking back at you. So, a lookout with height of eye of 36ft should be able to sight an object that is also 36ft above the surface, at a distance of 14nm (provided it's large enough to be seen at that distance to begin with). A good lookout, well trained and experienced, should be able to pick out the masthead of a ship well over the horizon. Of course, smoke can be a dead giveaway from an even much farther distance over the horizon.

04-30-17, 02:02 AM	#4
getbac Watch Join Date: Jan 2017 Location: Mountains of Central Utah Posts: 25 Downloads: 160 Uploads: 0	thanks yall very helpful......... the berbster told me the outer ring was visual but I could not understand it until now ... __________________ getbac/out

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04-29-17, 08:52 PM	#3
Sniper297 The Old Man Join Date: Dec 2005 Location: Philadelphia Shipyard Brig Posts: 1,386 Downloads: 160 Uploads: 19	This is an FAQ, so I made a new picture; The outer ring has nothing to do with radar, it's the average distance a lookout will see something the size of a surfaced submarine. Sometimes they'll see you further away, sometimes you can get in closer than the max circle, it depends on a variety of factors. Seeing a big ship on the horizon is a lot easier than seeing smaller ships and boats, that's why the outer ring doesn't go all the way to the horizon - a WWII sub was a boat, a small target difficult to see more than 4 to 5 miles away. The red half circle is the area where the sonar "pings" have a good chance of reflecting from a submerged sub strong enough to be detected. The yellow "3/4" circle is just listening for propeller cavitations and other noises like machinery and loading torpedoes, which is why there's a "SILENT RUNNING" option. Depending on how good the crew is, how fast you're going, how deep you are, and how far from the center of the circle you are, they might or might not hear you inside that semicircle. The reason for the cutout at the back is "baffles", sound interference from the ships own machinery and propeller noise.