More TVMDC – Practice Problems – Correcting and un-correcting the compass

TVMDC – Practice – Correcting and un-correcting the compassCorrecting and Un-correcting a compass is still a useful skill.  Paper charts and plotted course lines are still in use, even with today’s Cell Phone Apps and GPS Plotters.   If you take a Navigation or Piloting class that lasts more than 4 hours you will need these skills.  Here are 48 more Compass Correction practice problems to help polish your skills.

“Correcting” is converting a magnetic (M) direction to true (T). “Un-correcting” is converting from true to a magnetic direction. “True” direction is relative to true north (north pole).  Compass is the compass heading of the vessel.  Wind and current also have an effect on the Course To Steer (CTS), those outside effects are not addressed here but you need to be aware that they exist.

Variation is the difference between where a magnetic compass points and true north for a given point on the earth.  Variation is read from the compass rose on the chart. Variation is the same for all boats at the same point.  If North on the magnetic compass points to the East of True North the Variation is called EASTERLY.  If North on the magnetic compass points to the West of True North the Variation is called WESTERLY.

Deviation is the failure of the compass to point to magnetic north due to local magnetic fields on a boat.  These fields may be caused by the engine, instruments or other electronic equipment, power wiring, tools or any other magnetic objects. Deviation is specific to an individual boat. Deviation changes with the boats heading. Deviation is read from the Deviation Table on the boat.  Deviation will usually change for a boat based on the boats heading.

Compass error is the combination of Variation and Deviation.

Direction is written using three digits (000T (True), 000M (Magnetic) or 000C (Compass).

Use the same order for the formula working the solution either up or down, this always puts the same information in the same order, this makes checking the work easier and makes is easy for someone to double check the calculations.  NEVER do the good old piece of scratch paper where you just add one number to another, that seems to produce much higher rates of errors.

              ↓         T      ↑                True
     (-) E    ↓         V      ↑     (-) W	Variation
              ↓         M      ↑     	        Magnetic
     (+) W    ↓         D      ↑     (+) E	Deviation
              ↓         C      ↑                Compass

     Tele-Vision Makes Dull Children add Wonder.

     The heading must be uncorrected to provide a compass reading
     for the helmsman to steer.

 

Navigators Piloting and Charting Reference Card

Navigators Piloting and Charting Reference Card

Navigators Piloting and Charting Reference Card Reference card with help for correcting and un-correcting a compass, speed / time formulas and other quick hints for navigators.

Correcting Compass Error – More TVMDC Practice Problems and TVMDC help.

TVMDC – Practice – Correcting and un-correcting the compass – 24 more TVMDC compass correction practice problems.

Printer Friendly TVMDC practice sheets (pdf).  Printer friendly version of this exercise with answers.

TVMDC – Compass Correction Practice Problems

01 02 03 04 05 06
T 265 004 283 255 333 148
V 004W 014E 003E
M 285 140
D 005E 005E 003E 001W
C 290 246 327
07 08 09 10 11 12
T 290 232 097
V 019E 011W 014W 008W 007W
M 291 289 077
D 005E 005E 006E 001E
C 294 074 215
13 14 15 16 17 18
T 321 183 284 264
V 012W 017W 013E
M 307 135 293 335 270
D 003E 002W
C 303 204 288 333
19 20 21 22 23 24
T 062 147
V 008E 015W 007W 014E 009W
M 078 098 046 268
D 003E 002W 003W
C 000 075 041 130

TVMDC Compass Correction Practice Problems

25 26 27 28 29 30
T 285 012 213 003 118
V 014W 017E 011W 004E
M 226 006
D 005E 005W 006E 001E
C 231 002 106
31 32 33 34 35 36
T 090 287
V 015W 021W 023E 002W
M 062 079 144 308  020
D 004E 003E 003W
C 059 146 018 252
37 38 39 40 41 42
T 191 299 161
V 011E 009W 011E 005W
M 353 208 318
D 004E 001W 001E 003W
C 351 088 315 325
43 44 45 46 47 48
T 009 034 181 021 268
V 004E 011W 005E 015E
M 196 178 286
D 002E 004E 002W
C 002 199 180

TVMDC Compass Correction Practice Problem – Answers

01 02 03 04 05 06
T 265 004 283 255 333 148
V 004W 014E 002W 003E 003E 008E
M 269 350 285 252 330 140
D 005E 005E 005W 006E 003E 001W
C 264 345 290 286 327 141
07 08 09 10 11 12
T 310 290 275 232 097 207
V 019E 011W 014W 008W 020E 007W
M 291 301 289 240 077 214
D 005E 005E 005W 006E 003E 001W
C 286 296 294 234 074 215
13 14 15 16 17 18
T 321 123 183 284 348 264
V 014E 012W 017W 009W 013E 006W
M 307 135 200 293 335 270
D 004E 003E 004W 005E 002E 002W
C 303 132 204 288 333 272
19 20 21 22 23 24
T 011 062 083 039 147 259
V 008E 016W 015W 007W 014E 009W
M 003 078 098 046 133 268
D 003E 003E 002W 005E 003E 003W
C 000 075 100 141 130 271

TVMDC Compass Correction Practice Problem – Answers

25 26 27 28 29 30
T 285 012 213 355 003 118
V 014W 017E 013W 011W 004E 011E
M 299 355 226 006 359 107
D 005E 005W 005W 006E 003W 001E
C 294 000 231 000 002 106
31 32 33 34 35 36
T 047 090 123 287 043 247
V 015W 011E 021W 021W 023E 002W
M 062 079 144 308 020 249
D 003E 004E 002W 003E 002E 003W
C 059 075 146 305 018 252
37 38 39 40 41 42
T 004 083 191 299 337 161
V 011E 009W 017W 019W 011E 005W
M 353 092 208 318 326 166
D 002E 004E 001W 003E 001E 003W
C 351 088 209 315 325 169
43 44 45 46 47 48
T 009 034 181 021 193 268
V 004E 011W 015W 005E 015E 018W
M 005 045 196 016 178 286
D 003E 002E 003W 004E 002W 002W
C 002 043 199 012 180 288

 

Thanks to Captain’s Nautical in Seattle for letting me use one of their compass’s and letting me spread a chart out in the middle of their store on the floor while I took the picture  for the header.

Thanks for your interest in and support of boating safety

c / m

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