Jun 182014
 
timber

MNZ says loop lashing is the safest practice for securing timber deck cargoes in order to prevent damage or hazard to the ship and persons on board, and to prevent cargo loss.

Maritime New Zealand, MNZ, has issued a safety alert recommending loop lashing as the safest practice for securing timber deck cargoes to prevent damage or hazard to the ship and persons on board, and to prevent cargo loss.

A number of incidents have occurred around the world when best practice methods have not been used to secure cargoes resulting in injuries and loss of cargo overboard.

Says MNZ: “Any lashing practice must be able to overcome the transverse forces generated by the ship’s rolling movement. If the cargo is poorly lashed and the cargo moves during the voyage, it can cause a ship to lose stability. At present, the most common practice for securing timber deck cargoes to a ship is top-over lashing.”

Top-over lashing is a frictional lashing practice that applies vertical pressure that increases the friction force between the outer stows of deck cargo and the ship’s deck or hatch-cover. Top-over lashing as the sole securing practice for timber deck cargoes is sufficient only when the friction is very large or the expected transverse acceleration is very small. This practice is not recommended other than for vessels trading in restricted sea areas, inland or sheltered waterways.

Engineering analysis shows that loop lashing is superior to top-over lashing for security and safety when transporting timber deck cargoes throughout a sea voyage.

As a consequence of this, the International Maritime Organization (IMO) has discussed and reviewed its Code of Safe Practice for Ships carrying timber deck cargo. In 2011, the IMO revised regulation 5.4.1 in the Code of Safe Practice for Ships carrying timber deck cargo to include loop lashing as an optional practice to top-over lashing for securing timber deck cargoes.

MNZ recommends loop lashing as the safest and most secure practice for ships carrying timber deck cargoes throughout a voyage. Loop lashings are passed over the top-of-stow in opposing pairs to provide horizontal elements that best prevent the timber deck cargoes racking when considering all conditions at sea.

To secure the timber deck cargoes by loop lashing, the lashing isdrawn from the base of one side of the cargo, up and fitted across the top of cargo to a securing point at the top of the stanchion. Alternatively, the lower part of the lashing may be fastened to a securing point on top of the hatch-cover or deck underneath the cargo.

The ‘loop’ is then completed by rigging a second lashing in the opposing direction, so that the two lashings form one structure.

There are three practices of loop lashing that can be used to secure timber deck cargoes. These are:

  1. upright-fixed
  2. hatch-cover fixed
  3. deck-fixed.

Upright-fixed – this is the fastest securing practice. Less securing material and time is involved to secure the timber deck cargoes than with traditional chain and wiggle wire top-over lashing.

Upright-fixed. Source: Bain Shipping Services

Source: Bain Shipping Services

Hatch-cover-fixed – this version requires hog lashing to be placed in addition and separately to the opposing pairs of loop lashing.

Hatch-cover-fixed. Source: Bain Shipping Services

Source: Bain Shipping Services

Deck-fixed – this version is fixed in a similar manner to hatch-cover fixed.

Deck-fixed. Source: Bain Shipping Services

Source: Bain Shipping Services

Any of the above loop lashing practices can be used to achieve the best safe practice for transporting timber deck cargoes on a voyage. The ship’s fittings may determine the loop lashing practice selected.

These videos show the shortcomings of top-over lashing for securing cargoes:

This video shows the level of security the loop lashing practice provides to cargoes.

Download Safety Alert

See also:

Don’t Shiver Your Timber

What A Planker

 

 

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