Practice of anchoring / VLCC in deep water General Anchoring into "Deep water" which is defined depth of water is beyond 50 meter, must be carried out with "Walk-back Style, however, on the VLCC operation there exists such a big inertia, Master can treat with Walking-back style even in the anchorage where water depth less than 50m, if following conditions are to be forecasted a) Strong wind / current effect b) High density anchorage or anchorage with restricted area c) Indistinct depth of water or bottom material Principle procedure Walk-back chains If the area where water is depth beyond 50m, master should be considered he is going to anchor into the "deep water", all chains must be drawn out by "Walk-back Style" Ship's heading before commencing Walk-back chains Ship's heading on final approaching should be faced into the Wind and Current which can provide good advantage to control good ship's pose (heading) when Anchor just Folding and also for Minimizing of Swinging rate to windward or current-ward Ship's speed during Walk-back chains Ship's speed during Walk-back chain must be controlled as "0" with speed over the ground by GPS and/or Doppler Sonar, or less than speed of Windlass Walk-back Capacity (Speed) Brought-up anchor The status of brought-up anchor should be confirmed as holding chains by windlass brake after drawn out required length of chains Additional practice Astern engine Although, on R-FPP (Right turn Fixed Pitch Propeller) vessels, when ship is propelling with astern engine, ship's head turns to right as on theoretical, however, it's to be affected greatly by the primary inertia Swing-way shall be estimated totally with following factors a) Character of movement while using astern engine on FPR vessels b) Character that ships heading turns to windward This factor is remarkable as in ballast condition c) Drifting value of wind and/or current to lee side This factor is remarkable while ship's proceeding with low speed d) Trend of Wind / Current direction which ship's heading will follow e) Since in each case, Final inertia -way prior to anchoring is most affected to movement during Walk-back chains, this inertia can be managed occasionally with One Kick of Ahead Engine with Hard Angle of Rudder Approaching speed To plan as a gradual decrease as to secure remaining speed over the ground "0" by GPS speed when commencing to "Walking back Chains" by means of operating main engine to ahead and astern Note: Including anchoring at strong current area, it's required to confirm if the ship has been stationary with O.G speed by GPS and/or Doppler Sonar, also by all means of followings For the sake to be sure if ship has stopped moving completely, the master should check with following signs totally, even if no landmarks and signals are available to use a) Reports by Bow anchor watchmen with observing the condition of the cutwater on stem (and/or the anchor chain) b) Same as above, it's a good practice to use Hand-lead to check the fine movement c) GPS speed monitor on ARPA showing slight positive speed with the Owned cursor directing towards almost vertically with ship's heading d) Astern propelled wave has reached to forward of living quarter Walk Back speed On the standard, the weighing chain speed is 15cm / second (= one shackle 27.5 meter / minutes) Its corresponding to 0.3 kts of ship's speed It means ships speed with combining turning rate and drifting to wind and current lee side should be controlled less than 0.3 kts against direction anchor chain is going Do not use propelling beyond maneuvering Half Ahead / Astern Engine, except in emergency cases, once walk back is commenced Communication between commander in wheel house and bow anchor watchmen For the good image as macro-wise to actual ship's pose and condition of anchoring progress, Bow watchmen must report following to the Commander on the Bridge a) Approaching speed should follow a gradual decrease plan Before arriving at anchorage, Eye estimation speed by bow watchmen should be verified with GPS or Doppler log b) Reducing speed for anchoring Please note ship's speed is corresponded as follows 1.0 kts = aprx 50cm / sec 0.5 kts = aprx 25cm / sec 0.2 kts = aprx 10cm / sec c) Anchoring speed (Going walk-back) If ship is stationary just prior to anchoring with observing cutwater at stem and anchor chains in water d) Status chain number have been drawn on each shackle interval It is preferable to report as "XX shackles in the water" in order for the commander to easily visualize Length of chains being in the water and can estimate timing of touching anchor with bottom both commander and bow watchmen must acknowledge the length of anchor shank when taking account length of cable e) Anchor chain direction and tightness after bottom touch Report shall be combination of following factor For Horizontal direction: "clockwise" and "straight down" (or upright) For Vertical direction : "as Long hand (of the clock)" "as Short hand (of the clock) " For Tightness : "Strong tight", "Moderate tight, "Easy tight" and "Slack" Ex Chain - o'clock - as short hand - with moderate tight Related articles Routine Anchoring Operation Preparation for anchoring operations Planning for Anchoring Master Shall: Identify a suitable anchoring position before entering the anchorage area Conduct a planned approach including speed reduction in ample time and orienting the ships head prior anchoring to (a) Same as similar sized vessels around or (b) Stem the tide or wind whichever is stronger Decide on which method of anchoring to be used and the number of shackles depending on the depth of water, expected weather and holding ground A simple rule in determining length of cable to use: Standard condition: Length of cable = [(Depth of water in meters * 2) + 90 ] / 27.5 When good holding power can not be expected: (e.g Strong Wind, Strong Current, Harder Sea bottom) Length of cable = [(Depth of water in meters * 3) + 140 ] / 27.5 It is suggested the use of radar parallel indexing technique, an effective tool in maneuvering approach to anchoring position A fix reference point is necessary in establishing the intended anchoring position relative to this fix point Preparation for Anchoring The Chief Officer (or another experienced officer in lieu) must supervise letting go or weighing the anchors and should only assign experienced crew members to anchor work Prior to Anchoring, the Chief Officer should be aware of: a Approximate anchoring position b Method of approach c Which anchor to use d Depth of water e Method of Anchoring f Final amount of Cables Procedure of the Introduction to Anchoring At the Forecastle: Check brakes are on and clear the voyage securing devices (Anchor Lashings, Bow Compressed Bar etc.) a Start Hydraulic(Source of) Power of Windlasses b Check Anchor Shape / Light c Check Communication with the Bridge d Check Lighting on Forecastle including torch , at night time e Ensure all personnel are wearing Safety Helmets, Safety Shoes and Goggles Before Letting Go Anchor : The Chief Officer shall confirm that there is no craft or any obstacle under the bow and inform to the Bridge The Master shall ensure that the vessels GPS speed at the time of anchoring is near-zero or indicates a slight sternway The speed should be verified by visual transits and/or Radar ranges of Landmarks, if available or other fix conspicuous targets Where means of communication between Bridge and the Anchoring party is by Portable radio, the identification of the ship should be clear to avoid misinterpretation of instructions from other user of such equipment in the vicinity Routine Anchoring Operation There are methods for Anchoring according to depth of the water: Method (Preferable for Container Ships / Depths up to 50m ) a Walk out the anchor to Half a shackle above the sea bottom b Hold the cable on the brake and take the windlass out of gear c Stop the vessel over ground d Drop the anchor e Control the speed of cable flow by the brake , while not allowing pileup f Bring anchor cable direction forward and confirmed anchor holds its position Disadvantages: If the brake fails, or there is too much speed over ground, the cable will run out to the bitter end with consequent damage The brake lining could also be damaged due to this Dynamic load (the Static load on brakes to restrain movement of an anchored vessel is much less) Method (Suggested for Tankers / Depths over 50m ) a Stop the vessel over ground b Walk out the anchor under power until the complete length of required cable is paid out and anchor holds it position on the seabed c Bring anchor cable direction forward and confirmed anchor holds its position Disadvantages: Vessel must be completely stopped to avoid major damage to Windlass Particular Caution for VLCCs VLCCs, because of their inertia require great caution while anchoring They can suffer equipment failure if attempting to anchor whilst moving at speeds as low as half a knot over the ground Hence, the vessel must be nearly stopped not only in the linear direction but axial too, meaning the bow should not be swinging much either while anchoring The depth at which the vessel can safely anchor is about 110m or less, beyond which the windlass may have extreme difficulty in recovering the anchor Refer Further Practice of anchoring / VLCC in deep water for more details Emergency Anchoring Anchors should be ready for letting go on arrival and departure port, when in anchoring depths At least, any wire lashings are to be removed and the anchors held on brake In critical situations, to arrest the movement of the vessel, after stopping/reversing the main engine , it is preferable to let go both anchors simultaneously instead of one Anchor retrieval For weighing in the anchors, to reduce the load on the windlass, and keep the cable near vertical ,as required, short movements to be given on the main engine (and Bow Thruster used, where is applicable) The stay and direction of the cable and the residual shackles are to be continuously reported to the bridge Anchor Wash to be run to clean the chain and the anchor When anchor is fully hove, the brake is to be applied and the windlass taken out of gear The bow stopper is to be put when it is deemed safe to so Note: If it does not engage properly on the chain, then it is to be lowered across the chain as far as possible and lashed down in this position in such a manner, that if the cable does slip, the bar will fall into place across the chain Anchor watch An anchor watch is to be always kept when the ship is at anchor Anchor Watch Checklist is to be used Related articles How to deal with a damaged anchor? How to recover a lost anchor ? What is stranding ? Investigation of possibility of self-refloating and urgency of danger What are the emergency procedures for loss of anchor and chain? In case of damage to anchor and chain when to claim for '' general average"? ... vessel, after stopping/reversing the main engine , it is preferable to let go both anchors simultaneously instead of one Anchor retrieval For weighing in the anchors, to reduce the load on the