Section 4 Docking Surveys and In-water Surveys
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Naval Ships, January 2023 - Volume 1 Ship Structures - Part 1 Regulations - Chapter 3 Periodical Survey Regulations - Section 4 Docking Surveys and In-water Surveys

Section 4 Docking Surveys and In-water Surveys

4.1 General

4.1.1 At Docking Surveys or In-water Surveys the Surveyor is to examine the ship and machinery so far as necessary and practicable, in order to be satisfied as to the general condition.

4.2 Docking Surveys

4.2.1 Where a ship is in dry dock or on a slipway it is to be placed on blocks of sufficient height, and proper staging is to be erected as may be necessary for the examination of the outside of the hull, rudder(s) and underwater fittings. The outside surface of the hull is to be cleaned as may be required by the Surveyor.

4.2.2 The external shell plating is to be examined for excessive corrosion, structural deterioration from causes such as high stresses, chafing or contact with the ground, to areas of structural discontinuity and for undue unfairness or buckling. Special attention is to be given to the connection between the bilge strakes and the bilge keels.

4.2.3 The following parts of the external hull structure are to be specially examined:

  1. For steel hulls attention is to be given to parts of the structure particularly liable to excessive corrosion and to any undue unfairness of the plating of the bottom. The coating system is to be examined and made good as necessary.

  2. For aluminium alloy hulls attention is to be given to areas adjacent to any bimetallic connections at skin fittings, etc.

  3. For composite hulls the gelcoat or other protective finish is to be examined for surface cracking, blistering, abrasion or other damage which may impair the efficiency of the protection to the underlying laminate.

4.2.4 Where fitted, the satisfactory condition, attachment and operation of the cathodic protection (active or passive) is to be confirmed.

4.2.5 The sea connections, scuppers and sanitary discharges, their attachments to the hull and the gratings at the sea inlets are to be examined. Where applicable, pressure testing of the rudder may be required if deemed necessary by the Surveyor.

4.2.6 The clearances of the rudder bearings and pintles are to be measured. Where considered necessary by the Surveyor, rudders and stabilisers are to be lifted for examination of the stock. The securing of rudder and stabiliser couplings is to be confirmed.

4.2.7 Special attention is to be given to the hull in way of underwater fittings such as thrusters, shaft brackets, stabilisers, rudders, rope guards, eddy plates, GRP domes, bilge keels, echo sounders, and their attachments.

4.2.8 Where applicable, attention is to be given to the connection and/or intersection of the cross-deck structure to the hulls of multi-hull ships.

4.2.9 When chain cables are ranged, the anchors and cables are to be examined by the Surveyor, see also Vol 1, Pt 1, Ch 3, 5.3 Examination and testing – General 5.3.6 and Table 3.5.1 Survey preparation

4.2.10 For Surface Effect Ships any flexible skirts together with their attachment are to be examined.

4.2.11 For hydrofoil or foil assisted craft the attachment of foils is to be examined.

4.2.12 The Surveyor is to verify all draught markings as applicable at the time of dry-docking.

4.2.13 When Machinery Naval Class has been adopted, the following items are additionally applicable. The work is to be carried out in accordance with maintenance manuals and the manufacturer’s recommendations for servicing and renewals observed.

  1. The propeller and fastenings are to be examined. (Where a controllable pitch propeller is fitted, examination is to include blade fastenings and hub). The sternbush is to be examined as far as practicable.

  2. Where propeller shafts are wrapped for corrosion protection, the condition of the wrapping is to be confirmed.

  3. The clearance in the sternbush or the efficiency of the oil glands is to be ascertained. The clearance of any shaft bracket bearing is to be ascertained.

  4. The inboard shaft seals or glands are to be examined. Where flexible sternglands are fitted, the satisfactory condition of the rubber hose and securing clips is to be confirmed. Where inflatable shaft seals are fitted, their condition and operation are to be verified.

  5. Visible parts of side thrusters are to be examined. Other propulsion systems which also have manoeuvring characteristics (such as directional propellers, vertical axis propellers, water jet units) are to be examined externally with focus on the condition of gear housing, propeller blades, bolt locking and other fastening arrangements. Sealing arrangements of propeller blades, propeller shaft and steering column are to be verified.

  6. Where water jet units are fitted, the impeller, hull ducting, grating, nozzle steering and reversing arrangements are to be examined as far as practicable.

  7. Where podded propulsion units are fitted, the bearings and sealing arrangements, steering ring and thrust bearings in the hull are to be examined as far as practicable.

4.3 In-water Surveys

4.3.1 The Committee will accept an In-water Survey between Special Surveys, as a Docking Survey, where suitable protection is applied to the underwater portion of the hull. If requested, the *IWS notation may be assigned on satisfactory completion of the survey, provided that the applicable requirements of the Rules are complied with.

4.3.2 The In-water Survey is to provide the information normally obtained from the Docking Survey, see Vol 1, Pt 1, Ch 3, 4.2 Docking Surveys 4.2.2.

4.3.3 The underwater part of the hull should be marked with search lines for reference purposes.

4.3.4 The In-water Survey is to be carried out at an agreed geographical location under the surveillance of a Surveyor to LR, with the ship in sheltered waters and with weak tidal streams and currents. The in-water visibility is to be good and the hull below the waterline is to be clean. The Surveyor is to be satisfied that the method of pictorial presentation is satisfactory by use of CCTV. There is to be good two-way communication between the Surveyor and the diver.

4.3.5 Prior to commencing the In-water Survey, the equipment and procedures for both observing and reporting the survey are to be agreed between the Owners, the Surveyor and the diving firm.

4.3.6 The In-water Survey is to be carried out by a qualified diver employed by a firm approved by LR. In addition, for certain aspects of the In-water Survey, consideration may be given to the use of a remotely operated vehicle (ROV) operated by the LR approved firm.

4.3.7 If the In-water Survey reveals damage or deterioration that requires early attention, the Surveyor may, in consultation with the Owner, require that the ship be dry-docked in order that a fuller survey can be undertaken and the necessary work carried out.

4.3.8 Where a vessel has the *IWS notation, the condition of the high resistant paint is to be confirmed at each dry docking in order that the *IWS notation can be maintained.


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