The cold snap that hit the northern hemisphere, added to China's appetite for commodities, has created some of the worst traffic jams ever seen at ports handling bulk cargo.

Ships were queuing for an average of 27½ days to collect coal at Dalrymple Bay in Queensland, Australia, according to Global Ports, the analyst.

Simon Francis, Global Ports managing director, said 172 Capesize ships, the largest carriers of bulk commodities, were stuck in queues – nearly a fifth of the 960 Capesizes afloat.

Many smaller vessels are also queuing.

The hold-ups, rather than pushing up shipowners' earnings by cutting supply of dry bulk ships, were doing no more than preventing price falls, according to many involved.

Capacity has been added in the past six months as 100 Capesize ships have entered the market, either new or as conversions from obsolete single-hulled oil tankers.

The average spot market cost of chartering a Capesize ship stood at $42,242 a day on Friday, according to London's Baltic Exchange. This is below the spike of more than $80,000 a day in October but higher than feared in the wake of the large ship deliveries.

“I believe it's the congestion which is helping the market to maintain its current levels,” Michael Bodouroglou, chief executive of New York-listed Paragon Shipping, said.

Derek Langston, a director of consultancy and research at London-based SSY ship-brokers, said cold northern hemisphere weather was adding to strong demand for iron ore and coal – the main dry bulk cargoes – from China.

“The weather conditions stimulate demand for raw materials, which can help build congestion in places like eastern Australia,” Mr Langston said.

He said this was compounded by freezing conditions, which impaired operations across the supply chain.

He estimated that 35 Capesizes were waiting to berth at the main Chinese unloading ports of Caofeidian, Beilun and Qingdao.