2.5. Heavy Weather

Question 1

(a) Describe precautions to be taken prior to the onset of heavy weather.

Answer 1

• Check lashing arrangements of all cargo and loose gear
  on deck.
• Inform all departments.
• Ensure hatches, deadlights, watertight doors and ports
  are closed securely.
• On deck close gooseneck vents that may become
  immersed in water.
• Rig safety lines for the provision of safety harnesses for
  men working on deck.
• Close vent flaps and cowlings to cargo spaces.
• Eliminate free surface from slack tanks.
• Secure anchors and cover hawse and spurling pipes.
• Ensure deck free of loose mooring lines and ropes.
• Check liferafts secured properly.
• Check accommodation secure, including galley, stores
  and engine room stores.

Question 2

(b) Describe how certain types of vessels will handle in heavy weather

Answer 2

Beam – The greater the beam, the stiffer the vessel over the entire range of positive stability, particularly at smaller angles of heel.

Freeboard – Greater freeboard increases the vessel’s dynamic stability.

Draft – Increase of draft progressively increases KM, thereby reducing the GM values. Freeboard also reduces, so at Summer Load Draft a box-shaped hull will have a lower value and range of GZ compared to the same vessel in lightship condition.

Sheer – No effect on GZ values at small angles of heel, but by increasing reserve buoyancy the improve the range of a hull’s positive stability for a given GM value.

Superstructure – Ship shaped vessels have better stability characteristics when compared to a box-shaped vessel or a wall-sided vessel.

Question 3

(c) Describe the method for turning a vessel around in heavy seas

Answer 3

This is a potentially dangerous manoeuvre as the vessel may become swamped, and at the very least will roll heavily if the turn is not timed correctly.
Speed should always be reduced before turning so that the turn is carried out with the minimum of headway.
Helm orders must be bold.
Before turning inform all departments.
When turning in heavy seas storm oil may be of use.

Turning Downwind – Away from Head Seas:
Ensure the vessel experiences a relative calm when in a trough and commencing the latter half of the turn. It is likely that the vessel will be swamped in the second half of the turn so it should be done as quickly as possible.

Turning Upwind – Running Before a Head Sea:
Ensure the vessel experiences a relative calm in the second half of the turn. The bow may stall as it tries to overcome the wind effect while beam on so short bursts of full ahead will assist in bringing the bow around as quickly as possible.

a. In both cases use short bursts of full ahead to aid steering while keeping the headway to a minimum, and bold helm orders.

Question 4

(d) Describe action to be taken when the vessel is pounding excessively and access control on the decks

Answer 4

Trim the vessel by the stern to give better effect to the rudder and propeller, and reduce the vessel’s speed. This will minimise the amount the bow buries into the sea.
Consider the possibility of heaving to if a reduction of speed does not reduce the pounding.
Alter the vessel’s course to run with the seas on the shoulder.
Controlling Access to Main Deck in Inclement Weather:

a. Inform all departments that access to the main deck is prohibited, and that the master must grant permission before personnel are allowed to venture out.
b. Check all doors are securely closed during hourly rounds, and consider posting notices on all doors leading out of accommodation.
c. Prior to allowing any access to the main deck, a Job Safety Analysis or Toolbox Meeting should be held with all involved personnel. The possibility of slowing the vessel, altering course or turning to run with the seas should be considered and the effects these actions will have on the conditions on deck. This is especially important when sending a party forward to check securing arrangements of anchors and forward escape and cargo hatches.