Another bearing question

[overandout]

I read numerous posting about calculating bearing. It seems more important attacking a convoy in a storm. I figure to use the deck gun while heading 270 deg amd get notice of merchants bearing 300. I travel 30 deg (300-270 port) and still can't see them. Can anyone pls help me calculate the bearing? What formula to use? I thought to take my heading and subtract the enemy bearing. I sometimes stumble upon the ships and they start shooting at me before I can do anything! Any suggestions on setting myself up for success is appreciated.

Cheers,

Lee

[Diopos]

Heading 270° means that you are traveling towards the West.

Target at bearing 300° means the target is at 300° relative to your heading. If you turn 60° to the left you' ll bring the target at bearing 0°.

On the map -compass it is loacated at 270 +300 (or equivalently at 270-60)= 210°.

[I'm goin' down]

Your boat:
The bow of your boat is pointed at a relative bearing of 0 degrees. You can find its true course by tapping the equal key, and your sonarman will tell you. The bow of your boat will always be pointed at a bearing of 0 degrees, irrespective of the angle it is actually pointed. However, the boat's true course changes as the direction of the bow changes.

The target's relative bearing is its bearing relative to your boat's bow: The bow of your boat is always pointed at a bearing of 0 degrees regardless if your boat changes course. If the target is at a bearing of 90 degrees, that is 90 degrees relative to your boat's bearing of 0 degrees. If it is at a bearing of 270 degrees, that is 270 degrees relative to your boat's bearing of 0 degrees. For example, if a target is is at a bearing of 0 degrees, it is directly in front of the bow of your boat (point the periscope at 0 degrees). If you cannot see the target it is due to weather conditions or it is out of visual range. Don't confuse a target's bearing with its range from your boat. Your target could be miles away. A target at a relative bearing of 30 degrees lies at a point 30 degrees from the bearing of the bow of your boat which is pointing at a bearing of 0 degrees.

The target's bearing has no relationship to your boat's true course or the target's true course.

Target's true course. This is the direction the target is heading on the Nav Map:
0 degrees is true north, 90 degrees is true west, 180 degrees is true south and 270 degrees is true west. How about that? Just like a map that you buy at the store.

How to find true course on the Nav Map? Open the compass tool in the Nav Map. Surprise! A compass appears. The compass contains markings reflecting 0 - 360 degrees. Drag the compass on the Nav Map map making a line on the screen. The bottom of the compass intersects the line at a degree representing the true course. For example, please draw a vertical line (a perfectly vertical line) from the bottom of the map to the top of the screen with the compass tool. The bottom of the compass will intersect the line at 0 degrees. The heading is true north. If the target is heading in that precise direction, its true course is 0 degrees. If it is heading towards the bottom of the screen (i.e. heading in the exact opposite direction), drag the compass tool from the top of the screen to the bottom of the screen. The bottom of the compass will intersect the compass at 180 degrees.

In summary, A boat with a true course of 0 degrees is heading true north and one heading 180 degrees is heading true south. You can read those same numbers on the compass tool you are using as you plot its course. Regardless of the true course of your boat, its bow will always point at a bearing of 0 degrees. When you look through the periscope at 0 degrees, you should see the bow of the your boat.

That should get you started.

[Munchausen]

:cool: If the target bearing you get is from sonar ... and you cannot yet see the target ... turning toward the bearing will usually get you into visual range only if the target isn't moving ... or is moving along your course line (heading directly toward you or away). Otherwise, the target will drift one way or the other. If that's the case (your sonar operator can confirm it), you're not likely to get a visual if you try looking for it along the original bearing.

:shucks: You need to head it off at the pass!

[I'm goin' down]

:up:

[Platapus]

The target's bearing has no relationship to your boat's true course or the target's true course.



Let's just repeat this. Wish I had a buck for every single frickin time I got this confused in the heat of battle. :oops:

That and that whole confusing East West thing. :damn:

[I'm goin' down]

You are relaxed. You are falling asleep. You are not in a deep sleep. When you open your eyes, you have no idea where in the world you are, but you find yourself standing on the bow of your sub in the middle of the Pacific Ocean, looking straight ahead. You do not know if the sub is heading north, south, east or west. Why? Because you are lost, silly!

When you look at the horizon in the direction that your boat is heading, you are looking in the direction of a 0 degree relative bearing. That bearing has nothing to do with the true course of the boat, which, since we are lost, we do not know. To find the true course you need a reference point, such as the north star, to help you figure out your true direction. However, unless you use celestial navigation (it is a mod in the game, but it is too complicated for me), you need a tool to help you find true course. That tool is a map.

In the game, your reference point for true direction is the Nav Map. Imagine the map being round like a compass. Each degree on the circular map points in a different direction. The direction that your boat is heading on the map is its true course. The same principle applies to the direction of the target on the map. Again, you can get the true course of your own boat, not the target's, by tapping the = key on the keyboard with your periscope pointed a 0 degrees. Presumably, the navigator on the boat has given that data to the sonarman, who announces it when you tap the = key on the keyboard. The sonarman will give you the true course of your boat, but remember that has nothing to do with the boats relative baring. The bow of the boat, turning or not, is pointed a relative bearing of 0 degrees.

Now for the target: If a target is 30 degrees to starboard, point your periscope to 30 degrees (the target's relative bearing as viewed from your boat) and hit tap the = key on the keyboard. The sonarman will announce your new course, as you have ordered the boat to turn to a new course 30 degrees to starboard. Your boat will turn to 30 degrees and you will be heading in that direction. After the boat turns, your boat will still be heading at a relative bearing of 0 degrees (even thought it has turned 30 degrees), and the target will be straight ahead if it has not moved in the interim. The target will be ahead of your boat at 0 degrees relative bearing.

Thing of it this way. True course is the direction you are heading in the real world. Your reference point is a map and the directions are degrees on a compass.

Relative bearing is where the target is in relation to your boat. We know the bow of your boat points to 0 degrees relative to the other boat. The target's relative bearing is determined in relation to your boat.

Reread my posts--slowly.

You will now wake up and remember everything.

[tomoose]

As with aircraft using the clock system to indicate targets etc regardless of which direction the aircraft is flying, a sub or ship use the same idea except much more accurately.

So while an aircraft can be flying along a course of 315 degrees (relative to north which is 360 or 0 degrees) a crew member when yelling "bandit! 3 o'clock level" still indicates the target is 90 degrees to the right of the aircraft. The nose of the aircraft always points to 12 o'clock regardless of which direction it's travelling.

It's the same for ships/subs except they don't use the clock system, they use a 360 compass heading but still using the ship as the center and the bow always pointing to zero degrees so to speak. The confusion lies for some people in the fact that both the course and bearings use a similar reference (degrees). So to use the above example of the aircraft:

The sub/ship is zipping along on a heading of 315 degrees (relative to north). A crew member yells out, "ship spotted, 090 degrees!". The crew instinctively look 90 degrees to the right of the centerline of the boat.

http://img.photobucket.com/albums/v66/Tomaz99/SHIV/CourseversusBearing.jpg

Not sure if that helps or causes more confusion, LOL.:D
Having said all that I know that the sea dogs among us can explain expressions like "sail sighted, two points off the starboard bow" or "abaft" etc as that's also a similar "clock" method for sailors but in their own jargon.

[I'm goin' down]

[QUOTE=tomoose;1447592]reference (degrees).
The sub/ship is zipping along on a heading of 315 degrees (relative to north). A crew member yells out, "ship spotted, 090 degrees!". The crew instinctively look 90 degrees to the right of the centerline of the boat.

http://img.photobucket.com/albums/v66/Tomaz99/SHIV/CourseversusBearing.jpg

I quoted the portion of tomoose's post that I think will help you the most.

When the lookout says 90 degrees, he is telling you that he has spotted a ship at 90 degrees from the center of the his boat. The lookout does not know the course as he is looking though his binoculars while on duty in the conning tower. But he does know the the target's relative position to his boat, because he knows the bow of his own boat is always deemed to be pointing at at 0 degrees. The lookout is saying, "I do not know what true course our boat is heading, but at 90 degrees from our sub I have spotted a possible target." The possible target that he has spotted is at a position 90 degrees relative to his boat. That is its relative bearing. Why is it called "relative" bearing? Because it is determined in reference to the direction of our boat, which, without considering our boat's true direction (course), is deemed to be zero degrees.

Target's true bearing: We know from the map that the true course of your boat boat is 315 degrees. That is its direction in relation to true north. (Look at the map and confirm this.) However, we do not know any information about the true course of the target, as it could be moving towards your boat, parallel to it, or away from it. To figure out the true course of the target, you have to plot the target's course over time using the pencil tool, and then use the compass tool to determine its course. It the target's course is parallel to your boat, its true course would be 315 degrees also, but its longitude and latitude would be slightly different.

Got it?

[tomoose]

If you are in-game then it's simple to see this graphically. While on the bridge, use your binos or the bridge target bino and look at the readout in degrees in the top of the screen. You'll see when you are looking at the bow it's always 0 and the stern is always 180 etc. The binos are set up with the relative bearing indicated. Now have a look at your compass dial in the bottom right of your screen. That's your course/direction relative to north and obviously doesn't always correspond to your relative bearing info.

As I'm Going Down has stated, it doesn't really matter initially what course you are on when you hear one of your crew yell "ship (or aircraft) spotted, bearing XXX degrees" as that yelled bearing is always relative to your bow/stern centerline. This goes for your sonar guy too when he says "Merchant, bearing xxx, medium speed, long distance, moving away!" etc. The trick is to determine what your target's true course is, albeit roughly at first, so you can initially head in the right general direction and get more info/data which will firm up your plan of intercept/attack. Surface radar later in the war helps with this a lot.:salute:

[I'm goin' down]

then, you can confirm your true course (which the sonarman will announce when you tap on the = key) by looking at the ship's dials on left screen. The button dial is your boat and it is pointed in the direction of your true course, and it should so the degree at which you are heading.