Ship Mooring & Various types of Moor

 

MOORING: WHAT IS IT?

&

VARIOUS VESSEL MOORINGS

 

Tips for safe mooring operations

Mooring and unmooring operations hide a number of risks for those who get involved, many times leading to a fatal accident or a collision; Thus, it is of a great importance when conducting any mooring operation to follow specific steps to ensure the safety of all those conducting the operation.

 

1 Use Appropriate Lines

a. Choose based on size and operational requirements

Choosing the ideal mooring lines depends on local factors such as the water depth, the tidal range and wave energy, as well as on the material the mooring lines are constructed from.

The combination of both the material and the conditions where a vessel is to conduct its mooring operations, play a crucial role for the operation to be fruitful.

When opting for the mooring line keep in mind the:

• Weight and diameter of the line in comparison to required strength.
• Elasticity of the material.
• Durability including resistance to high temperature, strong sunlight or chemicals.
• Whether the lines will float or not.
• Required maintenance including method and ease of repair.
• Availability of replacement lines in vessels expected trading area.

b. Log new lines and know their exact position

When acquiring new mooring lines, it is vital to report them and know their exact position on the vessel. This can be easily achieved by keeping a log in which you may include the position for each line on board, manufacture date, date of first use on board and hours under tension.

2 Set an inspection system

Ensuring the ideal mooring operation, it is important to follow the steps below:

1. Calculate Estimated Life Expectancy
2. Set Retirement Criteria
3. Set Intervals for Routine, Detailed Inspection
4. Request 3rd-party assistance for Inspections
5. Residue Strength Testing

 

 

Inspections and maintenance should be conducted strictly according to the manufacturer’s instructions and be carried out by an expert. In that case, the vessel has the chance to request for 3^rd party assistance.

In addition, under the possibility that any damaged, defective or unserviceable piece of mooring equipment is found during inspections, it must be taken out of service and be either replaced or repaired.

#3 Plan operation

Another step to be taken prior to beginning the operations it is to exactly plan the procedure, creating a mooring plan based on mooring position, the area and the environmental conditions.

Also, the plan should be clear on the number of the lines that are going to be used in mooring and the crew in charge of the operation should assess the situation.

#4 Toolbox meeting

The toolbox meeting is a crucial step, not to be avoided, as those participating will in detail analyze the plan, the potential challenges and what mitigation measures will be followed.

Moreover, the meeting will provide safety instructions for those who will conduct the operations, so in case of emergency they will be able to handle the situation, and highlight that all mooring area is a snap-back hazardous area, meaning that all crew should be extra cautious during mooring.

David Nichol, Senior Loss Prevention Executive, UK P&I Club, speaking at a 2019’s SAFETY4SEA Forum commented that

Mooring and more particularly the handling of mooring ropes is an ancient skill that has adapted to larger ships and scaled up mooring machinery, but the basic risks and exposure to hazardous situations remain.

 

#5 Execute operation

Following the preparations, the plans and the alerts on the risks of mooring, the time has come when the crew has to provide the lines to shore party.

During the operation, it is vital to always have in mind the hazards and provide clean instructions to all parties, so that everyone is aware of their exact place and responsibility.

Keep in mind that communication is the key during operations, as all parties should follow orders and be informed during the execution of mooring.

In case of an abnormal situation, if something seems out of the plan, the crewmembers have to report it, so that it is rapidly handled, and any potential accident is prevented.

 #6 Post operation activities

After the vessel is safely moored and secured in a place, the crewmembers have to secure all lines, put everything back in place – as housekeeping is essential onboard a vessel – and then carry out the debriefing of a team.

During the debriefing the safety officer should debrief the crew referring to all stages of execution, as the crew should have regular follow ups on what they could improve in the operation; The debriefing, additionally, gives room for additional discussions on safety issues that were detected during mooring operations.

Did you know?

Did you know?

• During mooring operations “snap-back” is the sudden release of the energy stored in a tensioned mooring line when it parts as the mooring line reverts to its original length. The two ends of the line recoil or snap-back towards or past their secured ends. When a synthetic mooring line breaks, the snap-back effect can be extremely powerful and the rope ends may reach a high velocity as they recoil. Anyone standing within the snap-back zone at either end of the line risks serious injury or death.
• OCIMF’s MEG-4  includes new terminology, due to the confusion in the shipping industry with the term ‘Minimum Breaking Load’ (MBL); It is the core parameter against which all the other components of a ship’s mooring system are sized and designed with defined tolerances.

 

 LETS SEE VARIOUS MOORING TYPES:

Open moor

 

	Vessel anchored with both anchors leading ahead.
	Both the anchors remain 1point on the bow.

 

 

Procedures

 

	Approach the anchorage with wind or current on one bow.
	Weather anchor or upstream anchor is let go on the run (1).
	The headway continued and cable is laid up 1/3 rd of the final length of the cable.
	The second anchor is let go (2).
	First anchor snubbed at the gypsy.
	The vessel brings-to on her weather cable. It gradually grows taut to windward.
	Bow develops a rapid swing into the stream or wind.
	Both the anchors are veered.
	Finally the anchors are one point at each bow.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Standing moor, ordinary moor, dropping moor, straight moor

	Vessel required to moor with bridge along the dotted line.
	Stream ahead.
	Port anchor-5 shackles, stbd anchor-4 shackles.

 

Procedure:

	Head to stream or wind.
	When both are present, head to one has stronger effect.
	With sufficient headway, take vessel to position 1.
	Position-1 is roughly 5 shackles minus half ship's length beyond line AB.
	Let go port anchor.
	The vessel drifts downstream, render port cable to nine shackles, the sum of two lengths.
	She is brought up on her cable.
	Then the starboard anchor is let go at position-2.
	Vessel then moves to the position by rendering or veering the starboard cable and heaving in four shackles on the riding cable.
	Engines may be used to reduce stress on the windlass.

 

 

 

 

 

 

 

 

Running moor, flying moor

	Vessel required to moor with bridge along the dotted line.
	Stream ahead.
	Port anchor-5 shackles, starboard anchor-4 shackles.

 

Procedure:

Head to stream or wind.

	When both are present, head to one has stronger effect.
	Let go starboard anchor on run, when vessel is 4 shackles and half of ship's length (1).
	The cable is rendered as the vessel moves upstream.
	The cable is not allowed to be tighten, as bow will cant to starboard.
	The cable is rendered or veered 9 shackles and vessel moves to position-2.
	In position-2, port anchor is let go.
	The vessel moves stern.
	Five shackles weighed on lee (starboard) cable and five shackles veered on riding cable.
	The vessel is then brought up on her riding cable at position-3.

 

 

 

 

 

 

Advantages of mooring

	Vessel occupies little swinging room.
	Vessel turns almost to her length about stem.
	Scopes can be pre-adjusted for the prevailing strength of wind or stream.
	Scope of each cable is estimated in the same way as single anchor.

 

Disadvantages

	Lee anchor has no value to ship if headwind increases or vessel drags.
	Risk of getting a foul hawse.

 

 

 

Special precautions

	Maintain a constant watch to prevent foul hawse.
	Determine foul arc and clear arc.
	Vessel should always swing to clear arc on each tidal change.
	Use engine to give vessel correct sheer.
	Keep eye on the weather.
	Know the times of tide change.

 

 

Preference:

I will prefer standing moor. Because:

	Safer
	More control on the ship.
	The anchor is let go after vessel stopped.
	There is no possibility of damage due to anchoring at headway.

 

 

 

 

 

 

Baltic moor

	Employed alongside a quay.
	Used when construction of the berth is no sufficiently strong enough to withstand ranging in bad weather.
	Can be employed for berthing a vessel in an onshore gale wind.

Procedures:

	For a average size merchant ship, a 25-30mm wire is passed from the after ends on the poop, along the offshore side, outside and clear of everything.
	Offshore anchor is cockbilled.
	A man is send overside on a chair to secure the wire with the anchor, preferably at the shackle.
	The wire is secured with ship's rail by sail twine in bights.
	The aft end of the wire is sent to a wrapping barrel, ready for heaving slack wire.
	When the stem is abreast the position of the quay where the bridge will be positioned, the anchor is let go.
	The vessel is still on headway.
	About half a ship's length of the cable, the cable is surged and then snubbed.
	The wire is hove-in aft.
	The onshore wind will drift the vessel to the berth.
	The scope of the cable and the wire is adjusted and veered slowly until the ship is alongside.
	Distance of ship, length of cable and wire must be considered.
	Normally, the anchor is dropped at a distance 2/3 shackles length of the cable from the quay, which may vary depending on the prevailing circumstance.

 

 

 

 

 

 

Mediterranean moor

	Method of securing a vessel stern to the berth.
	Both the anchors leading ahead to hold the bow in position.
	The approach should preferably be made with the berth on port side.
	The starboard anchor is let go about two ships length from the berth(1).
	The vessel continues to move ahead.
	Starboard helm is applied and the cable is veered.
	The engines are then put astern and the port anchor is let go (2).
	As the vessel comes astern, transverse thrust swings the stern to port towards the berth.
	Stern lines are sent away.

 

 Conventional buoy or multi buoy mooring : 

 

1. In this method the bow of the ship is secured using both her anchors whereas the stern is secured to buoy around it .

2. In the approach firstly vessel approaches the final berthing position from forward at an angle of 90 degrees to her final direction of berthing.

3. The starboard anchor is then let go first at a pre decided spot while the ship is making headway.

4. Required amount of cable is paid and the astern propulsion too operated simultaneously to stop the vessel. 

5.Once the vessel is stopped in water port anchor is let go and thus vessel positions her stern along the centerline bifurcating the buoys .

6. For aligning the vessel along this centerline port cable is paid out and starboard cable heaved in with astern propulsion . 

7. The helm and engines to be carefully used during this maneuver to ensure the stern is swinging clear of any of the buoys. 

8. During unberthing the anchor cables are heaved in to move the vessel forward and the weight is taken on windward lines while casting off other lines to prevent swinging of the stern into the other buoys. 

9. This manoeuvre requires skill and efficient operation of ship’s crew as well as of the mooring equipments as often weight of the lines can be immense.

 

Single buoy or single point mooring : 

 

1.Often larger ships which cannot approach ports and terminal are berthed outside the port limits or in sheltered anchorages and the cargo transfer carried out with the help of Single point or single buoy moorings. 

2.The basic principle of the buoy is to keep the position of the vessel with respect to the buoy steady and at the same time allowing vessels to swing to wind and sea.. 

3.Often a tug is provided at the aft to keep the ship at a fixed angle and distance from the buoy. 

4.The buoy is fixed by positioning it in the centre of four anchors connected to it. The ship is made fast to the buoy with the help of a single chain or two which is secured onboard to the bow stopper. 

5.In general while approaching Single point or single buoy moorings weather is a major criteria in determining whether to berth the vessel or not. Calm seas with low swell and wind force below 15kts are considered favorable to make an approach. Presence of strong tidal current limits the interval for berthing and unberthing. 

6.The headway approach has to be slow often less than while at the same time approaching at a smaller angle to the buoy and then gradually hauling in the buoy messenger rope and pulling the vessel slowly towards the buoy using engine kicks at short intervals to control and maintain headway along with mooring winches to haul in the vessel when she nears about 150-200 meters from the buoy. 

7.For unberthing the chain is released from the bow stopper and a short kick on the engines going astern swings the bow to starboard for right handed propellers thus clearing the vessel of the buoy. Tug’s assistance can also be sued to pull the vessel astern and clear it of the buoy. 

Spider Mooring:

Spider mooring systems
 

Spider mooring systems are multi-point mooring systems that moor vessels to the seabed using multiple mooring lines.

Noramlly combination of 3 mooring lines(or as advised by mooring master) on one bouy each out of 4 buoys is used to moor ship.

While the vessel is in a fixed heading relative to the seabed, its bow typically heads into the dominant environment which is usually the direction where the largest waves are coming from.

The mooring lines can be directly attached to the hull of the vessel as well as indirectly using buoys on the sea surface.

 When they are directly attached to the hull, structural modifications are required to provide strong points for the mooring lines.

Spider mooring systems with buoys are called Conventional Buoy Mooring (CBM) systems and do not require any modifications to the vessel hull structures.

Procedure for spider mooring:

1. In this method the bow of the ship is secured using both her anchors whereas the stern is secured to buoy around it .

2. In the approach firstly vessel approaches the final berthing position from forward at an angle of 90 degrees to her final direction of berthing.

3. The starboard anchor is then let go first at a pre decided spot while the ship is making headway.

4. Required amount of cable is paid and the astern propulsion too operated simultaneously to stop the vessel.

5.Once the vessel is stopped in water port anchor is let go and thus vessel positions her stern along the centerline bifurcating the buoys .

6. For aligning the vessel along this centerline port cable is paid out and starboard cable heaved in with astern propulsion .

7. The helm and engines to be carefully used during this maneuver to ensure the stern is swinging clear of any of the buoys.

Then Set of 3 mooring lines are passed and made fast to each buoy. one on port bow & stbd bow each and one on each quarter. and vessel is made fast.

please see image👆

8. During unberthing the anchor cables are heaved in to move the vessel forward and the weight is taken on windward lines while casting off other lines to prevent swinging of the stern into the other buoys.

9. This manoeuvre requires skill and efficient operation of ship’s crew as well as of the mooring equipments as often weight of the lines can be immense.