What kind of maintenance mooring ropes require? What is the renewal criteria for them?

asked 01 Apr '18, 15:54

April 1, 2018, 3:54 p.m.
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Answer:

Some general guidance on the mooring gear maintenance:

Mooring Ropes

  1. Messenger ropes and heaving lines of sufficient number, strength and length and quality must be kept ready at the mooring stations, well in advance, especially prior ship to ship operations. All splicing made on the rope eyes should have minimum 5 tucks.
  2. Rope stoppers used must be of appropriate material, strength and length. Chain stoppers must not be used for synthetic ropes. They are to be used only for wire ropes.
  3. Synthetic ropes are associated with a danger called “SNAPBACK” which is the sudden release of energy stored in a stretched synthetic line when it breaks. Personnel should stand clear of the potential path of snap back.
  4. When making fast, ropes are not to be left on warping / drums or capstans drums, but must be layered on bitts, with one or two full turns around the leading post followed by sufficient figure of eight turns.
  5. All ropes in use must have a valid test certificate provided by the manufacturer. These certificates are to be kept in the vessel’s certificate file. If the ropes are supplied without certificates, the Master must contact office so that the certificate can be obtained. Ropes must be permanently marked or tagged for positive identification with their corresponding certificate.
  6. Mooring ropes are consumable items which will undergo constant physical change during their service. At the commencement of service the individual ropes will have their maximum breaking strength. A decrease in breaking strength is caused due to various factors such as exposure to sunlight, contact with seawater and chemicals, abrasion, corrosion, reduction of cross section area, fatigue, age, etc.
  7. A careful examination of ropes must be carried out by a competent person once a month. The inspection shall include a visual assessment of internal and external condition of the ropes using means for measurement and non-destructive testing methods:
    a) Fibre deterioration – break up or powdering of fibre is present.
    b) Damage due to external wear - wear down of strand crowns and/or significant number of outer yarns are severed.
    c) Local Abrasion – indicated by heavy chafing or fusion of surface fibre.
    d) Chemical Damage – indicated by staining.
    e) Thermal Damage – local fused sections on synthetic ropes indicates heat through friction.
    f) Excessive exposure to sunlight, sea water and the elements lead to accelerated deterioration.
  8. The Mooring ropes replacement is required if any of the following criteria are met:
    a) They have reached 36 months from the date first put into service.
    b) A physical condition assessment reveals non-suitability of mooring tail due to wear as illustrated in level D (refer c) The mooring rope is damaged due to physical or external conditions, rendered inelastic or found unsafe for further use.
    d) Ropes with any short break in strands length where the retaining strength reduces below 60% shall be discarded.
    e) Wherever local regulations require the mooring rope to be changed periodically.
  9. A minimum of 2 spare mooring rope shall be available on board. The quantity of spare mooring ropes may be increased depending on the number of mooring operation (such as STS operation) and trading area.

Mooring Tails

  1. The breaking strength of the tails used with wires should be at least 25% greater than the wire. (For Nylon ropes the value is 37%).
  2. The breaking strength of the synthetic ropes reduces dramatically depending upon the extent of wear. Based on the condition assessment of the mooring rope tails and the actual use, it is recommended to replace the mooring tail every 18 months from the time it is put in use. The rope condition largely depends on the usage and storage, thus a thorough inspection is necessary to ascertain whether mooring tails require replacement.
  3. The vessels shall maintain accurate records of mooring tails as follows:
    a) The competent person (Chief Officer or Master) having the necessary knowledge, shall carry out thorough physical inspection monthly. Guidance for condition based monitoring of residual strength is given below. b) A system to record the inspection and results from the inspection to assess the condition of the mooring rope tails, including the actual time in use. Mooring tails usage log must be maintained which shall calculate cumulative usage of each tail from the time it is put into use till replacement.
    c) All mooring tails to be tagged with canvass tags and certificates shall be maintained in Trading Certificate file.
  4. Vessel shall use a suitable cover on mooring tails while rolled up on the mooring winch for protection. The mooring tail eye shall be protected by a sleeve of canvas or an equivalent material. Mooring tails to be sweetened and stored inside the dry stores if the usage is not expected for extended periods. Mooring tails are to be examined during pre-arrival checks. No splicing is allowed on the tails, other than in way of the tail eyes.
  5. A minimum of 4 spare mooring rope tails shall be available on board. The quantity of spare mooring ropes may be increased depending on the number of mooring operation (such as STS operation) and trading area.
  6. The Mooring tail(s) replacement is required if any of the following criteria are met:
    a) A physical inspection reveals non-suitability of mooring tail due to wear beyond level C.
    b) The mooring rope tail is damaged, rendered inelastic or found unsafe for further use.
    c) Synthetic tails length must be measured every six months and replaced if their elongation exceeds 10% of the original length.
    d) A mooring tail has reached 1800 hours of usage as per mooring tails log.
    e) Wherever local regulations require the tails to be changed periodically (e.g., Japanese terminals require the tails to be changed every 18 months, irrespective of the condition).
  7. In exceptional cases where the mooring tails are utilized less frequently (such as on VLCCs), an extension beyond 18 months may be allowed (till 1800 hrs of usage) if other mentioned above parameters are acceptable.

Guidance on condition based monitoring of synthetic ropes / tails to determine residual strength.

Once the ropes have been put into use, the residual strength can be gauged by examining the general condition of the rope. For ease of reference, the ropes have been categorised as A to D depending upon the extent of chaffing.

1) Category A - Residual Strength > 95%. The rope is relatively new with minor abrasion on the external surface. Minor fuzz is apparent in some places on the surface

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2) Category B - Residual Strength 85% - 88%. Noticeable abrasion all around. Slight fuzz on external surfaces. The rope is still strong and useable.

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3) Category C - Residual Strength 75% - 78 %. Fuzz all around internal and external surfaces. Up to 1/4th yarns on a strand are damaged due to chaffing. Consider changing end to end and monitor the condition closely.

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4) Category D - Residual Strength 40% - 57 %. Significant abrasion and yarn damage along the length of the rope. 1⁄2 or more yarns are broken on a strand. The rope is likely to break at the area where the damage is maximum. This requires immediate replacement.

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answered 01 Apr '18, 16:49

April 1, 2018, 4:49 p.m.
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