Class III DP (DP3)
E4. Cruise, offshore energy and auxiliary/specialised fleetsDefinition
Single fault including fire in compartment does not cause position loss.
DP equipment Class 3 (DP3) is the highest IMO dynamic-positioning tier: DP2 redundancy plus physical separation, so no single failure including fire in any one compartment or flood in any one watertight space causes loss of position. Redundant thrusters, generators, switchboards, and DP controllers sit in A-60 fire-rated, separated compartments with independent cabling routes. Defined in IMO MSC/Circ.645 (1994) and MSC.1/Circ.1580 (2017), DP3 is specified for high-consequence work such as heavy lifts over live infrastructure and saturation diving where drive-off must be survivable.
Source: IMO MSC/Circ.645 (1994); IMO MSC.1/Circ.1580 (2017), DP system guidelines.