Chapter 5 Directional Control Systems
5.4 Control Position
5.4.1 All directional control systems shall normally be operated from the craft‘s operating station.
5.4.2 If directional control systems can also be operated from other positions, than two-way communication shall be arranged between the operating station and these other positions.
5.4.3 Adequate indications shall be provided at the operating station and these other positions to provide the person controlling the craft with verification of the correct response of the directional control device to this demand, and also to indicate any abnormal responses or malfunction. The indications of steering response or rudder angle indicator shall be independent of the system for directional control. The logic of such feedback and indications shall be consistent with the other alarms and indications so that in an emergency operators are unlikely to be confused.
C.5.4.4 Adequate indication which other operating position in service is to be provided at the operating station.
C.5.4.5 Controls are to be independent of one another, and so designed that the control system device cannot move unintentionally.
Chapter 6
Anchoring, Towing and Berthing
C6.0 Documents to be submitted
A detailed drawing, showing all the elements necessary for the evaluation of the equipment number of the craft, is to be submitted together with the calculations of the EN number. The anchoring equipment to be fitted on the concerned craft is to be specified.
Windlass, brake and chain stopper are subject to approval by the Society, the relevant documentation is to be submitted.
6.1 General
6.1.1 A primary assumption made in this chapter is that high speed craft will only need an anchor for emergency purposes.
6.1.2 The arrangements for anchoring, towing and berthing and the local craft structure, the design of the anchor, towing and berthing arrangements and the local craft structure shall be such that risks to persons carrying out anchoring, towing or berthing procedures are kept to a minimum.
6.1.3 All anchoring equipment, towing bitts, mooring bollards, fairleads, cleats and eyebolts shall be so constructed and attached to the hull that in use up to design loads, the watertight integrity of the craft will not be impaired. Design loads and any directional limitations assumed shall be listed in the craft operating manual.
6.1.4 Under any operating load up to the breaking strength of the anchor cable or mooring lines, the loads on the bitts, bollards, etc., shall not result in damage to the hull structure that will impair its watertight integrity. A strength margin of at least 25% above the resultant load based on the minimum specified breaking strength of the relevant cable or warp shall be required.
C6.1.4. Only anchoring equipment is considered for the purpose of classification.
6.2 Anchoring
6.2.1 High speed craft shall be provided with at least one anchor with its associated cable or cable and warp and means of recovery. Every craft shall be provided with adequate and safe means for releasing the anchor, its cable and warp.
6.2.2 Good engineering practice shall be followed in the design of any enclosed space containing the anchor recovery equipment to ensure that persons using the equipment are not put at risk. Particular care shall be taken with the means of access to such spaces, the walkways, the illumination and protection from the cable and the recovery machinery.
6.2.3 Adequate arrangements shall be provided for two-way voice communication between the operating compartment and persons engaged in dropping, weighing or releasing the anchor.
6.2.4 The anchoring arrangements shall be such that any surfaces against which the cable may chafe (for example, hawse pipes and hull obstructions) are designed to prevent the cable from being damaged and fouled. Adequate arrangements shall be provided to secure the anchor under all operational conditions.
6.2.5 The craft shall be protected so as to minimize the possibility of the anchor and cable damaging the structure during normal operation.
6.3 Towing
6.3.1 Adequate arrangements shall be provided to enable the craft to be towed in the worst intended conditions.
Where towage is to be from more than one point a suitable bridle shall be provided.
6.3.2 The towing arrangements shall be such that any surfaces against which the towing cable may chafe (for example, fairleads), is of sufficient radius to prevent the cable being damaged when under load.
6.3.3 The maximum permissible speed at which the craft may be towed shall be included in the operating manual.
6.4 Berthing
6.4.1 Where necessary, suitable fairleads, bitts and mooring ropes shall be provided.
6.4.2 Adequate storage space for mooring lines shall be provided such that they are readily available and secured against the high relative wind speeds and accelerations which may be experienced.
C6.5 Equipment
C6.5.1 General
.1 The anchoring equipment required in C6.5.2 is intended for temporary, occasional mooring of a craft within a harbour or sheltered area when the craft is awaiting berth, tide, etc.
.2 The equipment is therefore not designed to hold a craft off fully exposed coasts in rough weather or to stop a craft which is moving or drifting. In this condition the loads on the anchoring equipment increase to such a degree that its components may be damaged or lost owing to the high energy forces generated, particularly in large craft.
.3 For craft where frequent anchoring in open sea is expected, the owner's and shipyard's attention is drawn to the fact that anchoring equipment should be provided in excess of the requirements of these Rules.
.4 The anchoring equipment required in C6.5.2 is designed to hold a ship in good holding ground in conditions such as to avoid dragging of the anchor. In poor holding ground the holding power of the anchors will be significantly reduced.
.5 For small craft, with a length L 25 m, some partial exemption from these Rules may be accepted especially for what concerns anchor operation; in particular, where proper and safe anchor operation is assured, hand-operated machinery and/or absence of hawse pipe may be accepted.
C6.5.2 Equipment number C6.5.2.1 General
.1 The equipment is in general to be in accordance with the requirements given in Table C6.5.1, and may be reduced as per Table C6.5.2 in accordance with the ship's Service Restriction Notation.
.2 When two bow anchors are fitted, the mass of each anchor, the diameter and the length of each chain cable are to comply with the requirements of the above-mentioned table.
.3 The equipment number EN is to be calculated as follows:
0.1A BH 2 EN2/3 where:
△ = the maximum displacement (t)
H = effective height (m) from the summer load waterline to the top of the uppermost deckhouse, to be measured as follows:
i isin h a
H
a = the distance (m) from summer load water line amidships to the upper deck at side
hi = the height (m) on the centerline of each tier of deck houses having an actual breadth greater than B/4, where B is the breadth (m) as defined in C3.1.4 of Chapter 3
i = the angle of inclination aft of each front bulkhead as shown on Figure C6.5.1.
A = the area (m2) in profile view of the hull superstructures and deck houses above the summer load waterline which is within the rule length of the craft defined in C3.1.4 of Chapter 3 and with a breadth greater than B/4.
In the measurement of Σhi and A, sheer and trim are to be ignored.
If a deck house broader than B/4 is placed on top of another deck house equal to or less than B/4 in breadth, only the widest is to be considered and the narrowest may be ignored.
Windscreens or bulwarks and hatch coamings more than 1.5 m in height above the deck at side are to be regarded as parts of superstructures and houses when determining H and A.
In the calculation of A, when a bulwark is more than 1.5 m in height, the crosshatched area of Figure C6.5.1 is to be considered.
For catamarans, the cross-sectional area of the tunnel above the waterline may be deducted from BH in the formula.
C6.5.3 Anchors
C6.5.3.1 Mass of anchors
.1 Table C6.5.1 indicates the mass of a "high holding power anchor" (HHP) i.e. anchor having a holding power greater than that of an ordinary anchor.
.2 "Super high holding power anchors" (SHHP), i.e. anchors having a holding power equal to, at least, four times that of an ordinary anchor, may be used as indicated in Table C6.5.1.
.3 The actual mass of each anchor may vary within (+7, -7) percent of the value shown in the table, provided that the total mass of anchors is not less than would have been required for anchors of equal mass.
.4 Normally HHP or SHHP anchors are to be used. Possible use of ordinary anchors would be specially considered by the Society.
C6.5.3.2 Anchor design
.1 Anchors are to have appropriate shape and scantlings in compliance with Society requirements and are to be constructed in compliance with Society requirements.
.2 A high or super high holding power anchor is to be suitable for use on board without any prior adjustment or special placement on the ground.
.3 For approval and/or acceptance as a high or super high holding power anchor, the anchor is to have a holding power equal, respectively, to at least twice or four times that of an ordinary stockless anchor of the same mass.
.4 Comparative tests on ordinary stockless anchors are to be carried out at sea and must provide satisfactory results on various types of sea beds.
Alternatively sea trials by comparison with a previously approved HHP anchor may be accepted as a basis for approval.
Such tests are to be carried out on anchors whose masses are, as far as possible, representative of the full range of sizes proposed for the approval.
At least two anchors of different sizes are to be tested. The mass of the greatest anchor to be approved is not to be in excess of 10 times that of the maximum size tested and the mass of the smallest is to be not less than 0.1 times that of the minimum size tested.
Tests are normally to be carried out by means of a tug, but, alternatively, shore-based tests may be accepted.
The length of the chain cable connected to the tested anchor, having a diameter appropriate to its mass, is to be such that the pull acting on the shank remains practically horizontal. For this purpose a scope of chain cable equal to 10 is deemed normal; however lower values may be accepted.
Three tests are to be carried out for each anchor and type of ground.
The pull is to be measured by means of a dynamometer; measurements based on the bollard pull against propeller's revolutions per minute curve may be accepted instead of dynamometer readings.
Anchor stability and its ease of dragging are to be noted down, whenever possible.
.5 Upon satisfactory outcome of the above tests, the Society will issue a certificate declaring the compliance of
"high or super high holding power" anchors with its relevant Rules.
C6.5.4 Chain cables
.1 Bow anchors are to be used in connection with stud link chain cables whose scantlings and steel grades are to be in accordance with the requirements of the Society.
.2 Normally grade 2 or grade 3 stud link chain cables are to be used with HHP anchors. In case of SHHP anchors grade 3 chain cables are to be used.
.3 Proposal for use of grade 1 chain cables connected to ordinary anchors will be specially considered by the Society.
.4
a) steel grade of the studless chain is to be equivalent to the steel grade of the stud chains it replaces, i.e.
referring to ISO standard 1834:
– –
b) equivalence in strength is to be based on breaking load.
c) the studless chain cable meets the requirements of the Society.
.5 The proof loads PL and breaking loads BL, in kN, required for the studless link chain cables are given by the following formulae, where d, in mm, is the required diameter of grade 2 and grade 3 stud chain cables taken from Table C 6.5.1:
grade 2: PL2 = 9.807 d2 (44 –0.08 d) 10-3 BL2 = 13.73d2 (44 –0.08 d) 10-3 grade 3: PL3 = 13.73 d2 (44 –0.08 d) 10-3
BL3 = 19.61 d2 (44 –0.08 d) 10-3
.6 The method of manufacture of chain cables and the characteristics of the steel used are to be approved by the Society for each manufacturer. The material from which chain cables are manufactured and the completed chain cables themselves are to be tested in accordance with the appropriate requirements.
.7 Chain cables are to be made of unit lengths ("shots") of 27.5 m minimum joined together by Dee or lugless shackles.
C6.5.5 Steel wire ropes for anchors
.1 Steel wire ropes may be used as an alternative to stud link chain cables required in Table C6.5.1 when EN500, provided that the following requirements are complied with.
.2 The length Lswr of steel wire rope is to be not less than Lswr= Lch when EN 130
Lswr=Lch(EN+850)/900 when 130 < EN0
.3 where Lch is the length of stud link chain cable required by the Table C6.5.1.
.4 The effective breaking load of the steel wire rope is to be not less than the required breaking load of the chain cable it replaces.
.5 A short length of chain cable having scantlings complying with C6.5.4 is to be fitted between the steel wire rope and the bow anchor. The length of this chain part is to be not less than 12.50 m or the distance from the anchor in its stowed position to the windlass, whichever is the lesser.
C6.5.6 Synthetic fibre ropes for anchors
.1 Synthetic fibre ropes may be used as an alternative to stud link chain cables required in Table C6.5.1 when EN 130, provided that the following requirements are complied with.
.2 Fibre ropes are to be made of polyamide or other equivalent synthetic fibres, excluding polypropylene.
.3 The length Lsfr of the synthetic fibre rope is to be not less than Lsfr = Lch when EN 60
Lsfr=Lch(EN+170)/200when 60 < EN 130
where Lch is the length of stud link chain cable required by the Table C6.5.1.
.4 The effective breaking load Ps in kN, of the synthetic fibre rope is to be not less than the following value:
Ps = 2.2 BL8/9
where BL, in kN, is the required breaking load of the chain cable replaced by the synthetic fibre rope (BL can be determined by the formulae given in C6.5.5).
.5 A short length of chain cable complying with C6.5.5 is to be fitted between the synthetic fibre rope and the bow anchor.
C6.5.7 Attachment pieces
Both attachment pieces and connection fittings for chain cables are to be designed and constructed in such a way as to offer the same strength as the chain cable and are to be tested in accordance with the appropriate requirements.
C6.5.8 Arrangement of anchors and chain cables
.1 The bow anchors, connected to their own chain cables, are to be so stowed as to always be ready for use.
.2 Hawse pipes are to be of a suitable size and so arranged as to create, as far as possible, an easy lead for the chain cables and efficient housing for the anchors.
.3 For this purpose chafing lips of suitable form with ample lay-up and radius adequate for the size of the chain cable are to be provided at the shell and deck. The shell plating at the hawse pipes is to be reinforced as necessary.
C6.5.9 Windlass
.1 The windlass is to be power driven and suitable for the size of chain cable, and is to have the characteristics stated below.
.2 The windlass is to be fitted in a suitable position in order to ensure an easy lead of the chain cable to and through the hawse pipe; the deck, at the windlass, is to be suitably reinforced.
.3 The windlass is to be able to supply, for at least 30 minutes, a continuous duty pull Pc, in N, corresponding to the grade of the chain cables, given by the following formulae:
- for grade 2 chain cables: Pc = 42.5 d2 - for grade 3 chain cables: Pc = 47.5 d2
where d is the stud link chain cable diameter of the intended steel grade, in mm.
.4 The windlass unit prime mover is to provide the necessary temporary overload capacity for breaking out the anchor.
The temporary overload capacity or "short term pull" is to be not less than 1.5 times the continuous duty pull Pc for at least two minutes.
The speed in this overload period may be lower than the nominal speed specified in C6.5.9.5.
.5 The nominal speed of the chain cable when hoisting the anchor and cable may be a mean speed only and is to be not less than 0.15 m/s.
The speed is to be measured over two shots of chain cable during the entire trip; the test is to commence with 3 shots (82.5 m) of chain fully submerged, or with the longest practicable submerged chain length where the chain length does not allow 3 shots to be paid out.
.6 The windlass is to be provided with a brake having sufficient capacity to stop chain cable and anchor when paying out, even in the event of failure of the power supply.
.7 Windlass and brake not combined with a chain stopper have to be designed to withstand a pull of 80% of the breaking load of the chain cable without any permanent deformation of the stressed parts and without brake slip.
Windlass and brake combined with a chain stopper have to be designed to withstand a pull of 45% of the breaking load of the chain cable.
.8 The stresses on the parts of the windlass, its frame and brake are to be below the yield point of the material used.
The windlass, its frame and the brakes are to be efficiently anchored to the deck.
.9 Performance criteria and strength of windlasses are to be verified by means of workshop testing according to Society Rules.
C6.5.10 Chain stopper
.1 A chain stopper is normally to be fitted between the windlass and the hawse pipe in order to relieve the windlass of the pull of the chain cable when the ship is at anchor.
.2 A chain stopper is to be capable of withstanding a pull of 80% of the breaking load of the chain cable; the deck at the chain stopper is to be suitably reinforced.
However, fitting of a chain stopper is not compulsory.
.3 Chain tensioners or lashing devices supporting the weight of the anchor when housed in the anchor pocket are not to be considered as chain stoppers.
.4 Where the windlass is at a distance from the hawse pipe and no chain stopper is fitted, suitable arrangements are to be provided to lead the chain cable to the windlass.
C6.5.11 Chain locker
.1 The chain locker is to be of a capacity adequate to stow all chain cable equipment and provide an easy direct lead to the windlass.
.2 Where two anchor lines are fitted, the port and starboard chain cables are to be separated by a steel bulkhead in the locker.
.3 The inboard ends of chain cables are to be secured to the structure by a fastening able to withstand a force not less than 15% nor more than 30% of the breaking load of the chain cable.
In an emergency, the attachments are to be easily released from outside the chain locker.
.4 Where the chain locker is arranged aft of the collision bulkhead, its boundary bulkheads are to be watertight
.4 Where the chain locker is arranged aft of the collision bulkhead, its boundary bulkheads are to be watertight