What happens when there is a strong onshore wind and you have to berth a ship without the assistance of tugs to a pier or jetty that is not strong enough to bear the impact or is not sufficiently ‘fendered’?
In such a situations, the master or the pilot takes the recourse of using the ship’s anchor as well as the wires available on board in a specific way to minimize the impact of the fall. This is done by mooring ship in such a way where a vessel is berthed alongside the quay by employing a stern mooring shackled to the offshore anchor cable in the region of the ‘ganger length’. When approaching the berth, the offshore anchor is deployed and the weight on the cable and the stern mooring act in unison to hold the vessel just off the quay.
Baltic mooring is a combination mooring of a vessel alongside the berth which employs a stern mooring shackled to the offshore anchor cable in the region of the “ganger length”. When approaching the berth, the offshore anchor is deployed and the weight on the cable and the stern mooring act to hold the vessel just of the quay. Baltic mooring is a safe option to berth a ship on a windy day.
Now, there is a preparatory process to be undertaken before venturing for the Baltic moor.
– At first a 30 mm wire is passed from the poop deck on the offshore side from the outside of the hull and clear of any protrusions like the gangway, the pilot ladder etc.
– The anchor is cockbilled, i.e., released a little from the hawse pipe before finally letting it go, and a man is lowered with a bosun’s chair (a seat suspended from the ship to perform any work outside the ship’s hull) to tie up the wire to the anchor with a shackle at about the ganger’s length.
– The other end of the wire is taken ‘on turn’ upon a mooring winch through a bight.
– When the ship is abreast of the berth and falling on it rapidly, the anchor is dropped keeping trickle headway so that the anchor holds.
– When the anchor is snubbed, the wire from the stern that goes in with the anchor, gets taught and effectively holds the fall of the stern.
– The anchor chain is then slowly payed off and simultaneously the wire from the stern, while the on-shore wind pushes the vessel horizontally to the berth.
– As soon as the vessel is close -springs, head and stern lines are passed ashore with the heaving lines and the scope of the anchor adjusted accordingly so as to bring the ship slowly alongside the berth.
– Normally the anchor is dropped 70-100 feet off the berth depending on the wind force and the tonnage of the vessel.
It is always preferred to avoid mixed moorings due to variable loads and elasticity of various kind of ropes and wires which lead to different strain or weight on the lines. This can result in excessive loads on some lines than others and eventually part them putting the vessel in danger. However, for safety reasons or in a desperate situation shipmasters or pilots may have to resort to mixed moorings.
Vessels sometimes also use the seaward anchor in conjunction with mooring lines to haul the vessel out of jetty while casting off or while making fast the vessel alongside use the seaward anchor to assist the control of the rate of lateral movement towards the berth. This manoeuvre can be carried out with or without the assistance of tugs.
Ship to Ship transfer operation involves mooring alongside of two different or same sized ships for cargo transfer. During this operation either one of the ships is at anchor or both are underway. The mooring arrangement depends on the size of the ships. A vessel either at anchor or stopped and maintaining a constant heading is approached by the manoeuvring ship at an angle of approach as smaller as practicable. The region of approach is usually abaft the beam of the constant heading ship. During the approach as the manoeuvring ship comes closer, it steers a course parallel to the heading or course of the other ship and reduces the horizontal distance between ships to less than 100 metres. Once this state is achieved the manoeuvring ship uses engine and rudder movements and reduces this distance further until the fenders touch eachother. The two ships thus then make parallel contact and the lines are passed respectively as per the mooring plan. As a common practice during the approach the wind and sea are preferred to be from ahead or at very small angles to the bow.