Upside down compass on map tools

Hylander_1314 · 03-30-08, 11:20 AM

First click on your boat. Then move say at 45 degrees to the left and down. Your line that trails as you move the pointer should be matched up with 225 degrees on the protractor, giving you a proper bearing. This is based on the knowledge that 0 degrees is always north reguardless of what heading your boat is traveling.

So even if you are heading at say 295 degrees, your bearing will still be 225 on the protractor using the above example. This applies to the navigation, map only, and helps with calling out headings. This in reference to the compass. So if you want to change headings, to say 270 degrees, you call out, come to heading 270, not change heading 25 degrees to port.

Your readings on your TBT, binoculars, and periscopes will of course be based on what your heading is.

So if you are traveling at the same heading of 295 degrees, and you spot a ship 25 degrees off the port bow, you wouldn't call out ship spotted 2-7-0 degrees, even though that is where it would be on the map, you call out ship bearing 3-3-5 degrees. Since that is in relation to your heading.

It takes a little getting used to, but remember to keep navigation, and attack commands seperate.

Hope this helps!

I've been teaching my daughter this stuff when she takes the helm of my 16 ft. Runabout.

It's easier to explain in a 3d world, than it is to explain it on a 2d screen. As you have to imagine the 3rd dimention, of depth. If you have a compass, protractor, and ruler, you can practise on paper during the cruise, and apply your knowledge when in the heat of battle. It really helps when you have shallow waters nearby, and have to stay deep to avoid destroyers and aircraft.

spec24 · 03-30-08, 12:39 PM

ok, but when my sonar man calls out a contact at bearing 265, that's 265 deg in relation to my boat. As the front of my boat is the 0 deg that stays constant. A stationary freighter's bearing will change as I move around it (in other owrds). That 265 that the sonar called out is in relation to the 0 deg front of my boat. Bearing is in relation to my boat, not north 0 deg. I see, however, that it makes more sense when I drag from the target to my ship rather than my ship downwards (it does not equal 225 deg if I drag 45 deg down and to the left) with the compass tool.
For compass bearing it makes sense when you drage from the targets. It would be nice to be able to rotate them however.

Hylander_1314 · 03-30-08, 09:32 PM

I see your cofusion here. I don't use the map tools when hunting. I've gotten good enough over the years at doing the math in my head for bearing soundings, as to where they are in relation to my boat. If I get multiples for say a convoy, I'll use the trusty old pencil and paper.

Your point is well taken though. It would help to have a set of attack tools that could be used to assist in bearing, but it would have to stay constant with relation to the heading of your boat, or it would have to be made to rotate it so you could do so manually.

Munchausen · 03-31-08, 06:50 PM

As was done in real life, you need to convert relative bearing to true bearing. Easily done if you look at the bottom wheel of your TDC: find your relative bearing on the inner dial ... your true bearing is opposite it on the outer dial.

Now use your compass. Start at your sub's position and pull in the direction indicated on the "backward" compass rose.

04-01-08, 01:27 AM

Sonar man uses bearing. Your boat has a heading.

Bearings are allways relative to your boat - your heading is allways relative to north. Most of the time the skippers wrote the stuff as bearing 234 and heading 234 T (T telling it was relative to True North)

Look for the tool called "360 bearing" it gives you a "compass" that rotates with your boad when you zoom in close enough. Its included in the larger mods RFB and TM(i think).

Good luck

Buffalo9 · 04-01-08, 08:09 PM

Bearing is the inverse of your heading, hence N is inverse of S. That's why the plotting compass is upsidedown.

03-30-08, 11:20 AM	#1
Hylander_1314 Sea Lord Join Date: May 2006 Location: 5 Miles Inland West Of Lake Huron Posts: 1,936 Downloads: 139 Uploads: 0	First click on your boat. Then move say at 45 degrees to the left and down. Your line that trails as you move the pointer should be matched up with 225 degrees on the protractor, giving you a proper bearing. This is based on the knowledge that 0 degrees is always north reguardless of what heading your boat is traveling. So even if you are heading at say 295 degrees, your bearing will still be 225 on the protractor using the above example. This applies to the navigation, map only, and helps with calling out headings. This in reference to the compass. So if you want to change headings, to say 270 degrees, you call out, come to heading 270, not change heading 25 degrees to port. Your readings on your TBT, binoculars, and periscopes will of course be based on what your heading is. So if you are traveling at the same heading of 295 degrees, and you spot a ship 25 degrees off the port bow, you wouldn't call out ship spotted 2-7-0 degrees, even though that is where it would be on the map, you call out ship bearing 3-3-5 degrees. Since that is in relation to your heading. It takes a little getting used to, but remember to keep navigation, and attack commands seperate. Hope this helps! I've been teaching my daughter this stuff when she takes the helm of my 16 ft. Runabout. It's easier to explain in a 3d world, than it is to explain it on a 2d screen. As you have to imagine the 3rd dimention, of depth. If you have a compass, protractor, and ruler, you can practise on paper during the cruise, and apply your knowledge when in the heat of battle. It really helps when you have shallow waters nearby, and have to stay deep to avoid destroyers and aircraft. __________________ A legislative act contrary to the Constitution is not law. -John Marshall Chief Justice of the Supreme Court ---------------------

03-30-08, 09:32 PM	#3
Hylander_1314 Sea Lord Join Date: May 2006 Location: 5 Miles Inland West Of Lake Huron Posts: 1,936 Downloads: 139 Uploads: 0	I see your cofusion here. I don't use the map tools when hunting. I've gotten good enough over the years at doing the math in my head for bearing soundings, as to where they are in relation to my boat. If I get multiples for say a convoy, I'll use the trusty old pencil and paper. Your point is well taken though. It would help to have a set of attack tools that could be used to assist in bearing, but it would have to stay constant with relation to the heading of your boat, or it would have to be made to rotate it so you could do so manually. __________________ A legislative act contrary to the Constitution is not law. -John Marshall Chief Justice of the Supreme Court ---------------------

03-30-08, 12:39 PM	#2
spec24 Swabbie Join Date: Sep 2002 Posts: 13 Downloads: 12 Uploads: 0	ok, but when my sonar man calls out a contact at bearing 265, that's 265 deg in relation to my boat. As the front of my boat is the 0 deg that stays constant. A stationary freighter's bearing will change as I move around it (in other owrds). That 265 that the sonar called out is in relation to the 0 deg front of my boat. Bearing is in relation to my boat, not north 0 deg. I see, however, that it makes more sense when I drag from the target to my ship rather than my ship downwards (it does not equal 225 deg if I drag 45 deg down and to the left) with the compass tool. For compass bearing it makes sense when you drage from the targets. It would be nice to be able to rotate them however.

03-31-08, 06:50 PM	#4
Munchausen Commodore Join Date: Jul 2002 Posts: 608 Downloads: 25 Uploads: 1	As was done in real life, you need to convert relative bearing to true bearing. Easily done if you look at the bottom wheel of your TDC: find your relative bearing on the inner dial ... your true bearing is opposite it on the outer dial. Now use your compass. Start at your sub's position and pull in the direction indicated on the "backward" compass rose.

04-01-08, 01:27 AM	#5
Mav87th Stowaway Posts: n/a Downloads: Uploads:	Sonar man uses bearing. Your boat has a heading. Bearings are allways relative to your boat - your heading is allways relative to north. Most of the time the skippers wrote the stuff as bearing 234 and heading 234 T (T telling it was relative to True North) Look for the tool called "360 bearing" it gives you a "compass" that rotates with your boad when you zoom in close enough. Its included in the larger mods RFB and TM(i think). Good luck

04-01-08, 08:09 PM	#6
Buffalo9 Seaman Join Date: Apr 2008 Posts: 31 Downloads: 0 Uploads: 0	Bearing is the inverse of your heading, hence N is inverse of S. That's why the plotting compass is upsidedown.