Slow steaming has led to a 25% jump in charter rates for bigger containerships.

The 8,400-teu newbuildings Northern Jupiter , Northern Justice and Northern Jamboree have been fixed for up to two years at a significant premium to their sisterships.

The vessels, which are set for delivery between now and June, are said to have been taken by Mediterranean Shipping Co (MSC) at $14,000 per day for the first year with an option for another year.

The rates compare favourably with those for the sisterships taken from last April for similar periods at just $10,000 per day and $12,000 per day for the optional year.

The rise has been attributed to the increase in super-slow steaming by a range of lines, which continues to stimulate demand for vessels from 4,000 teu to 8,000 teu, as there are few ready for prompt delivery.

Slow steaming is likely to provide further impetus in the short term, with the lines of the CKYH Alliance announcing the introduction of slow steaming on all five of its services between Asia and Europe in the next few weeks.

The four partners - Cosco, K Line, Yang Ming Line and Hanjin Shipping - say the move will be implemented on the eastbound legs within the first half of the year.

Slow steaming is also being introduced on the transpacific trade as lines try to save on fuel costs.

Hanjin recently said it was going to introduce slow steaming on one of its Asia-to-US East Coast services. AXS-Alphaliner estimates that some 12 services between the Far East and the US West Coast have been slowed down, representing 32% of the total number of strings in the trade.

The slow-steaming stimulus may prove temporary but it has been helped by delivery delays to post-panamax ships.

Clarksons Research Services estimates that 46% of capacity expected last year had not entered the fleet by the start of 2010, restraining fleet growth to 6.3%.

Many strings in the Asia-to-Europe trades now consist of 10 ships rather than the traditional eight, while some are deploying 11. However, the sustainability of that demand depends on the lines' continued resolve to super-slow steam and on the delivery profile of newbuildings.

The market is bracing itself for another wave of super-slow steaming, with at least four more Asia-to-Europe and Asia-to-Mediterranean services confirmed as doing so from next month, according to PR News Services. That will result in Evergreen adding a 10th vessel on both its China Europe Shuttle (CES) Service and Far East/Mediterranean (FEM) Service. PR News adds that a ninth vessel is being added on the Asia Black Sea (ABX) service operated by China Shipping Container Lines (CSCL), K Line, Yang Ming, Wan Hai and Pacific International Line (PIL).

Earlier this month, Alphaliner said super-slow-steaming initiatives have prevented the layup of almost 50 containerships of between 3,000 teu and 13,000 teu, equal to 2.3% of the existing fleet.

Liner operators have reportedly throttled back on around 20 long-haul loops in the past two months, soaking up 250,000 teu of additional capacity by the end of February.

The analyst estimates that if the remaining strings were to stretch their existing rotations by one week through the addition of extra vessels, it would require 25 ships of between 3,000 and 8,000 teu or 137,000 teu of capacity.

This has already resulted in activity by major players with Mediterranean Shipping Co (MSC) leading the pack. It has taken the 5,116-teu Bellavia and Ottavia (built 2005) for a year at $7,500 per day and the 4,038-teu Mare Atlanticum (built 2000) for the remainder of the year at $6,000 per day. Meanwhile, French line CMA CGM is said to have taken the 5,762-teu ER Busan (built 2000) for between two and 12 months at $8,000 per day.