Heavy Lift , Effect of heavy lifts on the seaworthiness and stability of ship


A sea worthy ship- A ship that can take its cargo from one place to other without any danger or damage to both ship and cargo.

  1. Heavy lift cargoes, when loaded can have a great effect on the seaworthiness of the ship.
  2. Securing of these cargoes should be done in accordance with cargo securing manual & also the code for safe practice for cargo stowage and securing.
  3. If the cargo is not secured properly, the cargo may shift from its place during heavy weather which may result in the heavy list at sea and may also cause the vessel capsizing.
  4. Also, the heavy-lift may cause damage to ship’s watertight integrity resulting in flooding.
  5. The load density of the tank top should be capable of holding the weight of heavy cargo, without any structural damage.
  6. If vessel use its own gear to load or unload cargo , there is very large loss of GM (as once the crane has lifted the load the G will shift upward leading to loss of GM)

Effect of heavy-lift on stability

1.  when a weight is loaded on board the vessel a movement of ships G will be in the direction towards the weight being loaded

2. We know that once a weight is lifted its weight is effectively acting from the head of the derrick, the position of G of the ship will move upward .

3. This movement of G upward hence reduces the GM of the vessel making it less stable then before.

4. So depending on the condition, it would therefore make sense to lower the position of G of the ship in order to the anticipation of the rising G prior to the heavy lift is made.