What is a deviation card?

Asked By: Nansi Hanneman | Last Updated: 6th March, 2020
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A deviation card is produced after your onboard compass, usually located at the wheel binnacle, has been swung. Deviation is vessel specific and also varies dependent on the vessel's heading.

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Similarly, what is ship deviation?

Deviation is the error in reading a bearing from the compass caused by the magnetic influence of some nearby object, such as a metal post or an engine. In the case of boats it may even be due to the materials from which the boat is constructed.

Secondly, what is deviation curve? You can plot a graph of the effect of change in boat heading on the Deviation, this is called a Deviation Curve. Deviation can be measured by 'swinging the compass', that is, checking the compass reading when the boat is on a known heading, round a 360° series of headings, and plotting the resultant errors.

Likewise, people ask, what causes compass deviation?

In navigation manuals, magnetic deviation often refers specifically to compass error caused by magnetized iron within a ship or aircraft. This iron has a mixture of permanent magnetization and an induced (temporary) magnetization that is induced by the Earth's magnetic field.

How do you make a deviation table?

Five Easy Steps to Make a Sailboat Deviation Table

  1. Turn on standard equipment.
  2. Find your boat's deviation-free zone.
  3. Steer your Steering Compass- tracklines.
  4. Find the deviation.
  5. How to Use Your Deviation Table.
  6. Plot the trackline from starting point to destination.
  7. Enter the table and look under the Boat Heading column.
  8. Read the deviation in the second column.

37 Related Question Answers Found

How do you steer a ship by using a compass?

The lubber line (a small line on the compass) marks your direction on the compass card. The direction is given in degrees. You pick a course on a marine chart. Then, you steer the boat so that the lubber line points to the correct degree on the compass card.

What is the difference between true north and magnetic north?

Geographic north (also called "true north") is the direction towards the fixed point we call the North Pole. Magnetic north is the direction towards the north magnetic pole, which is a wandering point where the Earth's magnetic field goes vertically down into the planet.

Is a compass deviation card required?

My understanding is that a Compass Correction Card is legally required for an aircraft to be airworthy, per 14 CFR 23.1547: "§23.1547 Magnetic direction indicator. (a) A placard meeting the requirements of this section must be installed on or near the magnetic direction indicator.

What is variation and deviation?

Variation and deviation is used in celestial calculation to determine the magnetic compass error. Variation is difference between earth magnetic north and the geographical north. Deviation is the difference between earth magnetic north and the magnetic compass(fitted on ship) north.

What is a compass correction card?

Compass correction/deviation card. A small card placed in the cockpit to show the compass deviation for each heading. The card reads the courses to be steered in lieu of the required headings. Also called a deviation card.

How do you carry out a compass swing?

Performing the Compass Swing
  1. With engines running and aircraft in proper configuration, align the aircraft to the 0 degree (north) heading.
  2. Align the aircraft to the 90-degree (east) heading.
  3. Align the aircraft to the 180-degree (south) heading.
  4. Align the aircraft to the 270-degree (west) heading.

How do you find variations from a chart?

To find the variation for any given year we need the variation from the compass rose and the year for which it was correct, then add or subtract the annual change. This would be rounded up or down to the nearest whole degree for practical use. So the variation to use in 2007 is 7°W.

What is true course?

True Course: The aircraft's course over the ground relative to true north. True course is measured with a navigation plotter and a sectional map.

How do you do variation and deviation?

If the variation given is West and the annual Variation correction to apply is East then you subtract. Conversely if variation was East and the annual deviation correction to apply is West then you again subtract. If Variation given is West and the annual Variation correction to apply is also West then you ADD.

How do ships navigate?

An angle-measuring instrument called a sextant, to measure the angle of the stars above the horizon. A chronometer for telling time. Accurate charts so the navigator can find the position of the ship in latitude and longitude or in reference to the land or a hazard such as rocks and shallow water called shoals.

Why do they call it a compass rose?

Origins of the Compass Rose. The compass rose has appeared on charts and maps since the 1300's when the portolan charts first made their appearance. The term "rose" comes from the figure's compass points resembling the petals of the well-known flower. Naming them all off perfectly was known as "boxing the compass".

Do I add or subtract magnetic variation?

Use this mnemonic to remember that with variation west, the magnetic direction is going to be "best" or greater than true. Variation is added to true to arrive at magnetic, or subtracted from magnetic to get true. With variation east, magnetic will be "least" or less than true.

What is the difference between magnetic variation and magnetic deviation?

The difference between true north and magnetic north is called magnetic declination or magnetic variation. Some sources also erroneously refer to it as magnetic deviation. It's essential to take this phenomenon into account when navigating with a compass.

What is dip error?

An error in an aircraft magnetic compass. In the Northern Hemisphere, the compass lags behind the turn when turning left or right through a northerly heading and races ahead when turning through a southerly heading.

What is my magnetic deviation?

Magnetic declination, sometimes called magnetic variation, is the angle between magnetic north and true north. Declination is positive east of true north and negative when west. Magnetic declination changes over time and with location.