The lifecycle of your mooring line according to MEG4 is:
Black Rope will be glad to help at any point in the selection process – and can even advise operators from the very beginning in the process of choosing the right mooring line system set-up, offering possible alternatives for their individual needs.
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External abrasion
In principle, all type of contact with the rope will lead to some form of abrasion. The severity will depend on the type of rope in question and what the rope comes in contact with.
The following outlines some examples of what may cause abrasion:
• The type and design of fairleads affects the amount of abrasion mooring lines are exposed to.
• Closed fairleads should have a D/d of at least 15.
• Roller fairleads will usually have lower D/d ratios, but roller performance must be considered.
• Rollers that do not rotate result in significantly increased rope abrasion.
• As superyachts often exhibit very small D/d ratios in line with the equipment number, special attention needs to be paid in this respect.
• Slippage and other movement when on bollards.
• Avoid all type of movement on bollards as much as possible.
• Owing to the low friction coefficient of HMPE ropes, they should always be deployed with a cover in the bollard area.
• The potential for severe abrasion exists directly behind the eyes of mooring lines, as the rope is pulled over the edge of the quay when mooring and unmooring.
Internal abrasion
Internal abrasion is caused by the scissor motion of yarns or other material rubbing within the rope structure. This predominantly occurs when the rope is bent, particularly when under load. Dirt or other abrasive particles that enter the rope can also cause internal abrasion. Care should therefore be taken to avoid the rope coming into contact with such particles.
Excessive/ shock/dynamic/ continuous loads
Excessive loads can cause a rope to break. Mooring lines are exposed to dynamic loads and shock loads.
Dynamic loads:
The changing load conditions in the mooring line that can lead to excessive loads or shock loads
Shock loads:
When the load on the mooring lines increases very swiftly. If the working load of the rope increases by more than 10% within a very short timeframe, this is referred to as a shock load.
To protect the mooring line against potential damage, care should be taken to ensure that the dynamic load does not exceed 50% of the LDBF (Line Design Break Force).
Excessive shock loads can have serious consequences leading to a reduced breaking load and the risk of tearing in subsequent applications. Shock loads can cause:
• Fusing of rope fibres
• Rope becoming stiffer/less flexible
Play it safe!
Any rope that exhibits recognizable effects of being subjected to excessive shock loads should be retired immediately!
What happens when ropes break under load?
HMPE rope: Elongation at the point of break is low. The energy released during the break is high. High tenacity (HT) rope: High elongation at the point of break. A large amount of kinetic energy is released. High snapback! Danger!
Sharp deflections
If a mooring line is bent, such as on a roller/sheave, the bending action means there is a loss in strength. HMPE ropes are affected more in this respect by the effect of bending than HT ropes.
The effect is measured by the D/d ratio:
D = the diameter of the roller/sheave
d = the rope’s diameter (d).
As the D/d ratio decreases, the greater is the negative effect that the bending has on the rope’s strength.
Be aware that sharp deflections also lead to greater pressures being subjected to bollard, fairleads, etc.
For HM mooring lines, a D/d ratio of at least 15 should be applied, in accordance with OCIMF MEG4.
Exposure to UV light and chemicals
The exposure of mooring lines to ultraviolet (UV) light and chemicals should be avoided as much as possible.
• UV light and chemicals cause degradation of the ropes
• Degree of rope degradation depends on the raw materials used in their manufacture
• Exposure to UV light and chemicals can lead to a reduction in break loads and premature rope ageing
Please refer to the section on rope construction types and raw materials used (p. 15), for an overview on the UV light and chemical resistant attributes of the various mooring lines.
In instances where the lines have come in contact with chemicals:
• Rinse thoroughly with lukewarm running water only
• Inspect carefully to ensure the line’s suitability for further use
• Retire the line immediately, if necessary
Heat
Heat is a natural enemy of synthetic fibre ropes. Among the main causes of heat is friction, such as when ropes are used in closed hawses. This can lead to:
• Internal rope fusing
• Rapid wear
• Degradation
Exposure to high temperatures over extended periods can also lead to a reduction in the break load – without any visible sign.
To avoid damage, mooring lines should not be exposed to any external sources of heat or hot surfaces, such as:
• Exhaust funnels/pipes/systems
• Naked lights
• Anything causing friction
As different materials used in the construction of mooring lines will have varying levels of susceptibility to heat-induced damaged, please refer to the technical specifications for the fibres used in the rope types in question.
Please also refer to the appendix for examples of the effects of heat on synthetic rope and criteria for discarding damaged mooring lines.
Twisting / torsion
Prevent the twisting of mooring lines. Any twists should be eliminated prior to use. Longitudinal markings on the rope allow any twist to be identified quickly and easily. Moreover, twisting reduces the break load!
As a rule of thumb: Only four turns per meter cuts the break load by 10–30%.
Knots
Always bear in mind that knots reduce the strength of ropes. If the application does not explicitly require a knot, none should be used. If unavoidable, the working load must be reduced accordingly, to ensure safety.
Depending on the type of rope and knot used, a single knot can reduce the rope’s breaking load by approx. 40–80%!
info@blackrope.com , (+30) 69522 90682-3-4
acc. to MEG4
Conducting ongoing inspections of the mooring line system is a vital task to ensure the maximum service life and safety in every setup. It is important to be aware of and to define when inspections are to be undertaken and by whom.
1. Regular inspections by mooring crew members – upon each use
A visual inspection should be carried out by crew members prior to and during every mooring cycle in order to check for any damage. The inspection should follow the procedure of the checklist provided on page 25 of this manual. A logbook is to be maintained for each inspection and, if necessary, entries should be made to record any incidents, irregularities or observations. The defined rope retirement criteria are to be strictly observed.
2. Routine inspections by a qualified person – after the completion of mooring operation
The OCIMF MEG4 guideline prescribes that a routine inspection must be undertaken after the completion of mooring operation. Only qualified persons may conduct such inspections, who are in possession of a recognized degree or certificate of professional standing in an applicable field, or, who by extensive knowledge, training and experience have successfully demonstrated the ability to solve problems relating to the subject matter and work. During routine inspections, the qualified inspectors should walk the entire length of the line as well as the tail, to examine and document the current condition – and take any further necessary action.
3. Detailed inspections by a qualified person – after the 1000 mooring hours or after 30 mooring operations
The OCIMF MEG4 guideline prescribes that a detailed inspection must be undertaken after the 1000 mooring hours or after 30 mooring operations. Only qualified persons may conduct such inspections, who are in possession of a recognized degree or certificate of professional standing in an applicable field, or, who by extensive knowledge, training and experience have successfully demonstrated the ability to solve problems relating to the subject matter and work. During routine inspections, the qualified inspectors should walk the entire length of the line as well as the tail, to examine and document the current condition – and take any further necessary action.
Visual inspection
All types of wear and damage to the mooring line are to be identified by the mooring crew or a qualified person.
Walk the entire length of the rope and document its overall condition. Special attention is to be paid to contact points on deck, mainly with fairleads, as well as the cross point of split drums.
1. Abrasion/ cuts
2. Kinks/twisting/deformation
3. Inconsistent diameter
4. Glossy or glazed sections
5. Discoloration
6. Compression
7. Strand/ yarn breakages
8. Deformation caused by heat
9. Damage to splices
10. Other types of mechanical damage such as strong wear or general disaggregation
Refer to the examples of damage section in the appendix of this manual for further information on rope retirement recommendations.
Inspections following special incidents Should one of the following instances occur, the mooring line must be immediately inspected by a qualified person!
• Suspected exposure to an excessive shock load
• Clearly audible “cracking” of the mooring line
• Exposure to chemicals
• Unexpectedly strong twisting
• External mechanical damage
Wear zone management
Maximize safety and mooring system service life by ensuring all operators have a high level of awareness of the factors that cause rope damage and that appropriate precautions are taken to avoid damage.
Wear zone management. Mooring line systems are subjected to potential damage day in, day out, due to regular mooring activities. Also having an effect on this are the individual trading patterns of the ship including the design of the terminals being berthed at, the specific type of mooring system setup, the environmental conditions and ship movements while in port as well as the degree to which the ship is loaded. As the wear zone management techniques will vary with each vessel, it is important that these are assessed for each application and documented within the LMP in order to reduce the risk of rope damage most effectively.
Some effective techniques that can be included in an LMP to manage the wear zone include ensuring that:
1. Deck fittings are smooth to ensure mechanical damage is avoided
2. All sections of the mooring line system are protected from the elements and other environmental damage when not in use
3. Sharp deflections are avoided and that the D/d ratio is maximized
4. Interaction with deck fittings is controlled as swell, waves and wind will influence rope fatigue
5. Insufficient wraps around drums are avoided to minimize slippage
6. Mooring system lines are turned and interchanged to enable abrasion to occur evenly on rope sections
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Storage:
Following a few simple rules will ensure the mooring lines are correctly stored to prolong their service life and ongoing safe deployment:
• Make sure ropes are completely dry before storing
• Store in dry, well ventilated, dark rooms/areas (or at least adequately covered when on drums)
• Do not store near any sources of heat
• Avoid all contact with chemicals of any sorts
• Ensure the mooring line is not twisted when in storage
• Any mooring lines and tails on winches that are not in use should be protected against the elements with a waterproof cover
Care:
If necessary, rinse using running lukewarm water only.
Never store damaged rope! This may otherwise be inadvertently used and result in a serious risk of injury!
info@blackrope.com , (+30) 69522 90682-3-4
When should mooring system lines be replaced according to MEG4?
This is a fact that has to occur at some point and there is no way to avoid it. But the rate at which ropes age can be substantially influenced. Operators should be aware of all factors impacting on the service life of the mooring system in use on their vessel – and conscious that it has a direct effect on the safety of the crew and port staff. As a general guide, mooring system lines should be replaced when they reach a residual break load of 75% SDMBL.
Ropes should retire when they reach a residual break strength of 75% of SDMBL!
info@blackrope.com , (+30) 69522 90682-3-4