DYNAMIC POSITIONING CLASS OF DP VESSELS

This is in Continuation to my previous post about DYNAMIC POSITIONING SYSTEMS & DYNAMIC POSITIONING VESSEL found at :
http://www.jahajee.com/dynamic-positioning-systems-amp-dynamic-positioning-vessel/180/0.html

A Dynamic Positioning Classed vessel means the vessel must have a DP class notation from a Classification Society and not simply be fitted with Dynamic Positioning equipment. IMO has given guidance on DP equipment classification and redundancy requirements as follows :
  >>  Equipment Class 1 has no redundancy. Loss of position may occur in the event of a single fault.

  >>  Equipment Class 2 has redundancy so that no single fault in an active system will cause the system to fail.
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. (Two independent computer systems)
  >>  Equipment Class 3 also has to withstand fire or flood in any one compartment without the system failing. Loss of position should not occur from any single failure including a completely burnt fire sub division or fooded watertight compartment. (At least two independent computer systems with a separate backup system separated by A60 class division)

Based on the IMO guidance on DP Equipment Class main Classification societies have classed DP vessel in their own Class notations which can be downloaded from :
http://www.jahajee.com/dynamic-positioning-class/272.py

Again keeping things simple (for better understanding) ,  Class of Dynamic Positioning Vessel can be :
  >>  Dynamic Positioning Class 1 units with class 1 equipment, used during operations where loss of position is not considered to endanger human lives, cause significant damage or cause more than minimal pollution.
  >>  Dynamic Positioning Class 2 units with class 2 equipment, used during operations where loss of position could cause personnel injury, pollution or damage with great economic consequences.
  >>  Dynamic Positioning Class 3 units with class 3 equipment, used during operations where loss of position could cause fatal accidents, severe pollution or damage with major economic consequences.