1. Scope of the survey
1.1 When a ship is in dry-dock or on a slipway, it is to be placed on blocks of sufficient height and with the necessary staging to permit the examination of elements such as shell plating including bottom and bow plating, stern frame and rudder, sea chests and valves, propeller, etc.
1.2 The shell plating is to be examined for excessive corrosion or deterioration due to chafing or contact with the ground and for any undue unfairness or buckling. Special attention is to be paid to the connection between the bilge strikes and the bilge keels. Important plate unfairness or other deterioration which do not necessitate immediate repairs are to be recorded.
1.3 Sea chests and their gratings, sea connections and overboard discharge valves and cocks and their fastenings to the hull or sea chests are to be examined. Valves and cocks need not be opened up more than once in a special survey period unless considered necessary by the Surveyor.
1.4 Visible parts of rudder, rudder pintles, rudder shafts and couplings and stern frame are to be examined. If considered necessary by the Surveyor, the rudder is to be lifted or the inspection plates removed for the examination of pintles. The clearance in the rudder bearings is to be ascertained and recorded. Where applicable, pressure test of the rudder may be required as deemed necessary by the surveyor.
1.5 Visible parts of propeller and stern bush are to be examined. The clearance in the stern bush and the efficiency of the oil gland, if fitted, are to be ascertained and recorded. For controllable pitch propellers, the Surveyor is to be satisfied with the fastenings and tightness of hub and blade sealing. Dismantling need not to be carried out unless considered necessary by the Surveyor.
1.6 Visible parts of side thrusters are to be examined.
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| Bottom inspection routing |
1.7 Tailshaft Survey
Tailshaft survey means survey of propeller shafts and tube shafts (hereafter referred to as tailshafts) as well as survey of other propulsion systems.
1.7.1 Normal Survey
Propeller shafts and tube shafts are to be sufficiently drawn to permit entire examination at the following intervals unless alternative means are provided to assure the condition of the shaft:
(a) Where the propeller shafts and the tube shafts are fitted with continuous liners, or approved oil sealing glands, or made of corrosion resistant material, the interval of survey is to be:
- single shafting arrangement: three (3) years
- multi-shafting arrangements: four (4) years
The interval for drawing may be raised:
-
- from three (3) to a maximum of five (5) years for single shafting arrangements;
- from four (4) to a maximum of five (5) years for multi-shafting arrangements.
in any of the following three (3) cases:
where
the propeller is fitted to a keyed shaft taper the design details of which are approved, and a non-destructive examination is made at each survey by an approved crack detection method of the after end of the cylindrical part of the shaft (from the after end of the liner, if any), and of about one third of the length of the taper from the large end, or
Where
the propeller is fitted to a solid flange coupling at the aft end of the shaft,
the shaft and its fittings are not exposed to corrosion,
the design details are approved.
Non-destructive examination of the fillet radius of the aft propeller shaft flange may be required if the visual examination of the area is not satisfactory, or
Where
the propeller is fitted keyless to the shaft taper,
the shaft is protected from seawater,
the design details are approved, and
a non-destructive examination is made at each survey by approved crack-detection method of the forward part of the aft shaft taper.
In all other cases, the interval of survey is to be 2 1/2 years (+/- 6 months).
(b) The complete shaft is to be sufficiently drawn to permit entire examination.
However, for oil lubricated arrangement all exposed areas of the after shaft area as described in 1.7.1 (a) are to be examined by an approved crack-detection method without drawing of the shaft,
Where
- clearances and weardown of the bearings,
- records of lubricating oil analysis, oil consumption and bearing temperature, and
- visible shaft areas
are found satisfactory. The crack detection test of the aft flange fillet area may be dispensed with for the solid flange couplings fitted at the end of the shaft.
Lubricating oil and bearing temperature controls are to be performed as specified in 1.7.2(d).
Where any doubt exists regarding the findings of the above, the shaft is to be sufficiently drawn to permit an entire examination.
1.7.2. Modified Survey
(a) For single and multi-shafting arrangements the modified survey may be accepted in any of the following three (3) cases subject to:
-
- the shaft is fitted with oil lubricated bearings and oil sealing glands, and
- the shaft and its fittings are not exposed to corrosion, and
- new oil seals may be fitted without removal of the propeller (except in the case of keyed propeller), and design details are approved.
where - the propeller is keyed on the shaft taper and suitable crack-prevention measures are taken, or
where - the propeller is fitted to a solid flange coupling at the end of the shaft, or
where - the propeller is fitted keyless to the shaft taper.
(b) The modified survey is accepted at alternate five (5) yearly (maximum) surveys instead of the Normal Survey, provided that the clearances of the aft bearing are found in order and the oil and the oil sealing arrangements have proved effective.
(c) The modified survey consists of:
- drawing the shaft to expose the aft bearing contact area of the shaft,
- examining the forward bearing as far as possible and all accessible parts of the shaft including the propeller connection to the shaft, and
- for keyed propellers, performing a non-destructive examination by an approved crack-detection method of about one third of the length of the taper from the big end, for which dismantling of the propeller will be required.
- for keyless propellers performing a visual examination to confirm the good condition of the sealing arrangements.
(d) Where a lubricating oil analysis is carried out regularly at intervals not exceeding six (6) months, and the oil consumption and bearing temperature are recorded and considered to be within permissible limits, drawing of the shaft to expose the aft bearing contact area of the shaft may not be required.
The documentation on lubricating oil analysis is to be available on board. Each analysis should include the minimum parameters:
- water content,
- chlorides content,
- content of bearing metal particles, and
- oil aging (resistance to oxidation).
Oil samples should be taken under service conditions.
1.7.3. Partial Survey
(a) For shafts where the modified survey is applicable, consideration may be given, upon application by the Owner, to a prolongation of the intervals between Normal Survey, provided a partial survey is performed.
(c) The partial survey consists of checking the oil sealing glands and the clearance of the bearings.
For keyed propellers, the propeller is to be dismantled to expose the forward part of the taper and a non-destructive examination by an approved crack-detection method is to be performed.
(c) In no case is the interval between Normal Survey to exceed 1.5 times the due interval.
Note: Special consideration may be given in application of relevant sections of this Unified Requirement to commercial vessels owned or chartered by Governments, which are utilized in support of military operations or service.
NOTE: For the survey of propeller shafts, Periodicity of complete survey of tailshaft. Refers to Figure 1
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| Figure 1 |
(a) with shaft withdrawn, subject to modified survey at 5 years plus or minus 6 months
(b) with shaft in place, subject to modified survey at 5 years plus or minus 6 months.
(b) with shaft in place, subject to modified survey at 5 years plus or minus 6 months.
Note 1: Shafts protected against corrosion are those:
- made of corrosion resistant material, or
- fitted with continuous liners or systems considered as equivalent, or
- fitted with oil lubricated bearings and oil sealing glands.
Note 2: Suitable sealing glands are glands which are type approved by the Society with regard to protection of the sterntube against ingress of water.
1.8 Special consideration may be given in application of relevant sections of this Unified Requirement to commercial vessels owned or chartered by Governments, which are utilized in support of military operations or service.
2. In-Water Surveys
2.1 The In-water Survey is to provide the information normally obtained from a docking survey. Special consideration shall be given to ascertaining rudder bearing clearances and stern bush clearances of oil stern bearings based on a review of the operating history, on board testing and stern oil sample reports. These considerations are to be included in the proposals for in-water survey which are to be submitted in advance of the survey so that satisfactory arrangements can be agreed with the Classification Society.
2.2 The In-water Survey is to be carried out with the ship in sheltered water and preferably with weak tidal streams and currents. The in-water visibility and the cleanliness of the hull below the waterline is to be clear enough to permit a meaningful examination which allows the surveyor and diver to determine the condition of the plating, appendages and the welding. The Classification Society is to be satisfied with the methods of orientation of the divers on the plating, which should make use where necessary of permanent markings on the plating at selected points.
2.3 The equipment, procedure for observing and reporting the survey are to be discussed with the parties involved prior to the In-water Survey, and suitable time is to be allowed to permit the diving company to test all equipment beforehand.
2.4 The In-water Survey is to be carried out by a qualified diver under surveillance of a Surveyor. The diver is to be employed by a firm approved as a service supplier according to requirements (refer to IACS UR Z17).
2.5 The Surveyor is to be satisfied with the method of pictorial representation, and a good two-way communication between the Surveyor and divers is to be provided.
