Dead Reckoning

Dead Reckoning — the process of continuously and sequentially accounting for the elements of vessel movement — course and distance travelled — relative to an initial point, for the purpose of determining and predicting the vessel position at any given time.

Dead Reckoning is based on the continuous accounting of the direction and magnitude of vessel displacement over time.

Menu path

Transition to dead reckoning mode

ECDIS transitions to dead reckoning mode in the following cases:

• Automatically when GNSS receiver data is unavailable

• When an observation performed by manual methods is accepted for dead reckoning

DR mode operating features

ECDIS automatically switches to dead reckoning mode without applying set and drift — DR. Dead reckoning starts from the last valid position; COG/SOG calculation is discontinued.

If speed (STW) and/or heading (HDG) sensors are available, coordinates are calculated from compass and log data.

Important

When navigating by dead reckoning, errors accumulate. To correct the growing error, it is recommended to correct the coordinates using manual and other backup position-fixing methods.

№	Element	Description
1	Dead reckoning	Dead reckoning elements
2	Drift	Drift elements
3	Correction	Entry of permanent corrections to navigational parameters

№	Element	Description
1	Dead reckoning coordinates	Dead reckoning coordinates. When dead reckoning mode is off, data from the primary position sensor is fed to these fields. To shift the vessel position to entered coordinates (for example, after determining coordinates by astronomical methods) — press Apply
2	Apply	Applies the entered coordinates. Available when DR mode is on
3	Forced DR mode activation	Toggle for forced activation of dead reckoning mode
4	Go to Manual Observations	Go to Manual Observations for vessel position correction
5	Manual course input	Manual course input. When selector (6) is off, data from the heading sensor is fed to this field
6	Enable manual course input	Selector to enable manual course input
7	Manual speed input	Manual speed input. When selector (8) is off, data from the speed sensor is fed to this field
8	Enable manual speed input	Selector to enable manual speed through water input

№	Element	Description
9	Latitude correction	Enter latitude correction
10	Longitude correction	Enter longitude correction
11	Course correction	Enter course correction
12	Speed correction	Enter speed correction

№	Element	Description
13	Set and drift speed	Set the set and drift speed
14	Set and drift direction	Set the set and drift direction. In ECDIS, the set and drift direction is directed from the compass
15	Set and drift timer	Set and drift timer. Maximum set and drift accounting time is 3 hours. The timer starts when selector (16) is enabled and when set and drift parameters are changed. 5 minutes before the set and drift accounting time expires, ECDIS displays a notification with a countdown: When the set and drift accounting time expires, ECDIS discontinues set and drift accounting and generates a notification:
16	Set and drift enable selector	Toggle to enable set and drift accounting

Simple dead reckoning mode

When ECDIS transitions to Dead Reckoning (DR) mode, the navigational indicator displays the data source — DR, and the values are highlighted in yellow.

№	Element	Description
1	Dead reckoning vessel position	Dead reckoning vessel position without set and drift; in dead reckoning mode, the coordinates field is orange
2	Vessel speed vector	Vessel speed vector
3	DR mode indicator	DR — indicator of dead reckoning mode without set and drift

Set and drift accounting

When set and drift accounting is enabled, ECDIS calculates the course over ground vector and the track line relative to the ground.

№	Element	Description
1	Dead reckoning vessel position with set and drift	Dead reckoning vessel position with set and drift; in dead reckoning mode, the coordinates field is orange
2	Position by alternative source	Position by an alternative coordinate source. For example, from a GNSS receiver
3	EP mode indicator	EP — indicator of dead reckoning mode with set and drift
4	Manual input indicator	MAN — indicator of manual course and speed input
5	Set and drift indication	Indication of set and drift direction and speed on the navigational panel