Although self-unloading ships have been around for some time, they have never really attained widespread popularity, except in some specific niche markets and for certain closed-loop trading patterns for commodities such as cement.
However, there are signs of wider acceptance, despite depressed bulk freight rates, as ship operators look to develop markets using specialised ships able to command better charter rates.
Essentially, there are two main mechanical systems available - bottom gravity discharge or top discharge - as well as mechanical/pneumatic systems for powdery cargoes such as cement and hybrid systems using shipboard cranes in conjunction with deck and boom conveyors....
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Approx 2000 words from Bulk Materials International, November/December 2001,
page 17.
