Section 1 Scope
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Ships, July 2022 - Part 5 Main and Auxiliary Machinery - Chapter 9 Podded Propulsion Units - Section 1 Scope

Section 1 Scope

Parent topic: Chapter 9 Podded Propulsion Units

1.1 General

1.1.1 This Chapter applies to podded propulsion units where used for propulsion, dynamic positioning duty or as the sole means of steering.

1.1.2 For the purposes of these Rules, a podded propulsion unit is any propulsion or manoeuvring device that is external to the normal form of the ship’s hull and houses a propeller powering device.

1.1.3 The requirements of this Chapter relate to podded propulsion units powered by electric propulsion motors, (and are in addition to the requirements for Electric Propulsion in Pt 6, Ch 2, 16 Electric propulsion and other relevant Sections). Podded propulsion units with other drive arrangements will be subject to individual consideration.

1.1.4 The structural requirements stated in Pt 5, Ch 9, 4.1 Pod structure, Pt 5, Ch 9, 4.2 Hull support structure and Pt 5, Ch 9, 4.3 Direct calculations relate to podded propulsion units having a pod body with single supporting strut with or without an integral slewing ring arrangement, see Figure 9.1.1 Podded propulsion unit. Novel and unconventional arrangements will be subject to individual consideration. In such cases, the designers are advised to contact LR in the early stages of the design for advice on the manner and content of design information required for formal classification appraisal.

1.1.5 The aft end structures associated with podded installations are to be examined with respect to potential slamming, see Pt 4, Ch 2 Ferries, Roll On-Roll Off Ships and Passenger Ships.

1.1.6 It is the shipbuilder's responsibility to ensure that all installed equipment is suitable for operation in the location and under all anticipated environmental conditions associated with the design of the ship which is to include temperature, humidity, vibration and impulsive accelerations.

1.1.7 The design of a podded propulsor system is to take into account a range of operating conditions which are to include the following:

  • All ahead seagoing conditions up to and including the maximum rated output of the podded propulsor while maintaining a steady course under foreseeable sea and wind conditions.
  • The ability of the ship to change direction rapidly at the declared steering angles with the ship running at maximum ahead service speed.
  • Executing a steady turning manoeuvre with a tactical diameter not greater than 5L and advance not greater than 4,5L whilst maintaining a power corresponding to the test speed, where L is the length measured between the aft and forward perpendiculars. Test speed is defined as a speed of at least 90 per cent of the ship's speed corresponding to 85 per cent of the maximum rated power of the podded propulsor.
  • Changing heading, manoeuvring in and out of harbour both ahead and astern, at slow speeds, stationary and starting from rest in foreseeable current and wind conditions.
  • Berthing manoeuvres in the case of azimuthing podded propulsion units.
  • Rapid acceleration and deceleration manoeuvres where the ship's operating profile demands this capability.
  • Holding stationary positions over-ground under different conditions.
  • Stopping manoeuvre as required byPt 5, Ch 1, 5.2 Sea trials.
  • Manoeuvring in ice where ice class is required.

Figure 9.1.1 Podded propulsion unit
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