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Introduction (1 August 2020)

Part 6, Chapter 1, Section 3, Paragraph 11.3 (6-1-3/11.3) of the ABS Rules for Building and Classing Marine Vessels (Marine Vessel Rules) contains requirements that the ice loads on azimuthing main propulsors for Polar Class vessels be considered.6-1-3/11.3.1.i and 6-1-3/11.3.1.ii both refer to 6-1-2/29, "Appendages", but 6-1-2/29 does not offer guidance on the applicable ice loads or loading scenarios for azimuthing main propulsion units.

These Guidance Notes offer design ice load formulations intended to assist designers and engineers in determining the ice loads on azimuthing main propulsion units to comply with 6-1-2/29. These Guidance Notes also offer assistance by referring to the Marine Vessel Rules sections that are required to be complied with. Section 1 covers definitions and explanations of the loading considerations for the design ice loads given in Section 2.

These Guidance Notes are intended to assist propulsion unit designers in order to obtain structural approval on units intended for vessels of ice classes PC1 through PC7. "Structural" here refers to the shell plating and internal structure of the propulsor body, strut, and nozzle (as applicable). The ice loads on the propeller blades and drive train components are covered elsewhere within Section 6-1-3 of the Marine Vessel Rules. The methods offered in these Guidance Notes are not mandatory, and designers may offer an alternative approach and methodology to demonstrate that their design meets the intent of the Rule requirements provided in 6-1-2/29. Any alternative approach shall be submitted to ABS for approval.