The California Block Stow (CBS) method of stowing steel slabs was developed by the California Steel Industries a number of years ago. The idea behind this method is to speed up loading and discharge operations on vessels.
The system involves loading steel slabs straight upwards in a fore and aft direction, one slab on top of the other, in free- standing stacks interlinked with square timber and secured by Steel Strapping bands using the ‘Olympic’ lashing method only on top tiers. This may give rise to an unacceptable risk of cargo shift that would pose a serious threat not only to the safety of cargo, but also to the vessel itself and her crew.
In most instances, a gap between stow and the ship’s sides of about three metres is left without any securing.
In conventional slab stowage, the only securing is with timber driven between any gaps in the top tier slabs. With the CBS system, after loading and securing with steel strapping bands, the dunnage compresses and the bands slacken off.
Thomas’ Stowage, arguably one of the leading authorities on stowage and carriage of cargoes, states inter alia that stowage of slabs in normal type bulk carriers should be winged out, over the lower wing tanks, to the ship’s sides, overlapping and fully dunnaged in every tier.
In a recent case, where a bulk carrier loaded nearly 15500 metric tons of steel slabs using the CBS method in Italy for the US East Coast, only a week into the voyage during rough sea with heavy swell, the cargo in all five holds collapsed to port.
This caused a list of about 12 degrees. Thus, the vessel had to put into a port of refuge so that the cargo could be restowed and relashed in accordance with recommendations given by the surveyors attending on behalf of the various parties involved. A General Average was declared.
Interestingly, the surveyors in attendance also agreed that steel brackets should be welded in each cargo holds in order to contain the stow and prevent shifting, but other than that, the restowage plan was essentially the same as had been used at the load port, i.e. the CBS method of stowage.
Subsequently it was discovered that the stevedores in load port had wrongly increased the number of slabs in each stack in one of the cargo holds, creating an excessive load on tank tops. The stow had to be undone and restowed. The vessel eventually sailed and discharged her cargoes without any further incident.
The reason why California Block stowage is attractive to charterers is that it saves costs on loading and discharging.
Given the concerns regarding the safety of the method, however, it seems that the cost saving argument is not a good enough reason to put the cargo, vessel and crew at risk.
For this reason, Skuld does not recommend the use of the CBS method of stowage and lashing.