The DP Classes

Here below there are the classes of DP according to the IMO (International Maritime Organization) and the Classification Societies. The IMO apply the rules to vessels built after July 1st 1994.

IMO

Class 1 Loss of position may occur in the event of a single fault.

Class 2 Loss of position should not occur from a single fault of an active component or system such as generators, thruster, switchboards, remote controlled valves etc. But may occur after failure of a static component such as cables, pipes manual valves etc.

Class 3 Loss of position should not occur from any single failure including a completely burnt fire subdivision or flooded watertight compartment. A single fault includes a single inadvertent act by any person onboard the vessel.

The Classification Societies define the different class as follows:

ABS
DPS 1 Vessels are to be fitted with a dynamic positioning system which is capable of automatically maintaining the position and heading of the vessel under specified maximum environmental conditions having an independent centralized manual position control with automatic heading.

DPS 2 Vessels are to be fitted with a dynamic positioning system which is capable of automatically maintaining the position and heading of the vessel within a specified operating envelope under specified maximum environmental conditions during and following any single fault excluding a loss of compartment or compartments.

DPS 3 Vessels are to be fitted with a dynamic positioning system which is capable of automatically maintaining the position and heading of the vessel within a specified operating envelope under specified maximum environmental conditions during and following any single fault including a loss of a compartment due to fire or flood.

D.N.V.
AUT An automatic position keeping system with a remote thrust control back up and a position reference back up.

AUTR An automatic position keeping system with redundancy in Technical design.

AUTRO An automatic position keeping system with redundancy in technical design and physical arrangement.

Lloyds
DP(AM) This notation is assigned when a ship is fitted with automatic and standby manual controls for position keeping and with position reference system(s) environmental sensor(s) and machinery arrangements as defined in section 5.2 (within LR Rules)

DP(AA) This notation is assigned when a ship is fitted with automatic and automatic standby controls for position keeping and with position reference system(s), environmental sensor(s) as defined in section 5.3 (within LR Rules).

DP(AAA) This notation is assigned when a ship is fitted with automatic and automatic standby controls for position keeping together with an additional/emergency automatic control unit located in a separate compartment and with position reference system(s), environmental sensor(s) and machinery arrangements as defined in section 5.3 (within LR Rules).