Anchors The specific requirements for anchoring equipment in ships are laid down by the Classification Societies and is determined as per each ship's displacement, her wind area down to the summer load line. These requirements are the weight of anchor, number of anchors, length of chain cable and breaking strength.Requirements also specify that the cable must be secured in the chain locker by an arrangement whose breaking strength is greater than 15% and less than 30% of the tensile proof stress of the chain (Norske Veritas). Also, the breaker of the windlass must be able to withstand a … [Read more...]
The Pivot Point
A Pivot Point is a central point on a vessel which remains fixed as the bow and stern swing around it. Fixed is not really correct, because it moves forward or aft as the vessel moves through the water as stated below: 1. Ship stopped Unless stated otherwise. Each example assumes a ship on an even keel in calm conditions and still water. In this situation, no forces are involved and the ship has a pivot point coinciding with its centre of gravity approximately amidships.2. Making Headway Two forces now come into play. Firstly the forward momentum of the ship and secondly, longitudinal … [Read more...]
Shallow Water Effect on Ship
Shallow water effects on a ship w.r.t "Draft & Maneuverability." • As the hull moves through shallow water, the area which it displaces is not so easily replaced by surrounding water, therefore, leading to a state of partial vacuum as the propeller and rudder are still working. The vessel take-ups longer to answer her helm, and response to engine movements becomes sluggish.• In these circumstances, vibration will be set up, and it will be extremely difficult to correct a yaw or sheer with any degree of rapidity.• At normal speed it is found that steering becomes erratic when the … [Read more...]