6 items with the tag Ships

Slow steaming a long term viable option


A good presentation from Wartsilla explaining the inital challenges faced by 2 stokes engines to perform slow steaming as makers had designed those engines for a much higher load.

The optimal load range of the two-stroke engine lies between 70-85%. The fuel efficiency of the engine, its operational parameters, the specification of the turbochargers, coolers, auxiliary systems, exhaust gas boilers, and so on, are chosen and optimised for that normal load range. It is natural, therefore, that when the engine is operated continuously in a load range below or even far below 60%, the overall system is no longer fully optimised.

However shipping lines can save a lot bunker tons (and x3 of CO2 emissions) by reducing ship speed. As an example reducing speed from 27 to 22 knots (-19%) will reduce the engine power to 42% of its nominal output (CMCR). This results in hourly main engine fuel oil savings of approximately 58%. A further reduction down to 18 knots saves as much as 75% of the fuel.

Wartsilla after due considerations concluded that the modern two-stroke engines are able to reliably operate in all load ranges between 10% CMCR and 100% CMCR without major modifications, if recommendations are followed.

The possible consequences of continuously operating at reduced load without taking the recommended precautions are:

  • Lower air flows A problematic area after the auxiliary blowers cut out / before they cut in. The possibility of very high exhaust, and thus component temperatures.
  • Poor combustion Poor atomisation. Higher sac volume: injected volume ratio, increased likelihood of dripping. Increased fouling and carbon deposits likely.
  • Cold corrosion Caused by condensation of corrosive vapours. Possible when observing very low engine temperatures during very low load operation.
  • Fouling Of the exhaust system, turbochargers, exhaust boilers Z Of the scavenging air space due to excess cylinder oil. Apart from these engine related concerns, concerns have also been voiced about efficiency losses (e.g. propeller, turbochargers, shaft generators, heat recovery systems) and the accelerated deterioration of condition and performance (e.g. fouling of the hull and propeller due to reduced ship speed, stern tube seals, shaft bearings).

The presentation can be found here:

View online : Presentation

Slow steaming new paradigm in liner trade


Slow steaming major impact on the liner industry is not well understood.

One leading marine analyst said recently in an article on the market that slow steaming is a murky concept: QUOTE "Roughly speaking, that means the industry is carrying 20% of spare capacity. This calculation of surplus can be fine-tuned by allowing for changes in tonne-miles and slow steaming. But, the former is a murky concept, since the globe does not get any bigger, and most ships are designed to go at 85% MCR, so the minute rates go up the fleet will no doubt speed up. UNQUOTE

Slow steaming existence in liner trade is simply based on the price of bunker vs. the price of ships. The extra costs by adding a ship to a rotation must be more than covered by the savings of bunkers for all the other ships of the rotation. And the higher the bunker the more likely slow steaming makes sense.

The additional capacity which is absorbed by slow steaming is a consequence, not the cause for slow steaming. Slow steaming is not there on temporary basis, it is there to stay, and the world liner fleet will not speed up until the bunker savings vs. ship price equation change, which is unlikely when there is too much capacity .

The fact that ship engines are designed to run at 85% MCR is neither a reason for slow steaming to stop. The engine system might not be optimized below 60% MCR, however manufacturers have found ways to circumvent the technical drawbacks (lower air flow, poor combustion, increased fouling and corrosion…etc.) and even guarantee a safe operation as low as 10% MCR.

On the biggest 2 strokes engines, going down from full speed to 18 kts reduce fuel consumption by 75%, or bunkers actually represent more than 50% of shipping lines fixed costs.

Slow steaming is likely creating a new paradigm for liner shipping, as new ships being optimized for lower speed; provide higher bunker savings which translate into a slot cost advantage.

Managing capacity will remain high on the agenda for some years as ship owners will have no choice but to order new ships to remain competitive in an Industry guided by economy of scale. Maersk line returns to profitability clearly show how important it is to have the lowest cost.

And unless the industry and the world economy recover quickly, old inefficient ships might not find a fixture. This is a serious risk for all ship owning funds and definitely for the German KG since Germany ten top banks have USD 128 Billion in outstanding credits related to the global shipping industry. That is more than double the value of their holdings of government debt from Greece, Ireland, Italy, Portugal and Spain.

See the article on http://www.oceotrade.com/-rubrique38-

LNG Fuel cells


Can fuel cells powered by LNG be used for ships propulsion?

The short answer is not before many years, as the technology for large power storage battery is not yet available. Below please find an interesting article from Marex on the subject.

To the best of my knowledge the mentioned min 200 KWH battery required for ship propulsion seems to be underestimated for commercial ships. Existing commercial diesel-electric prop ships require between 14 MW (I.e. support vessel LOA 130m, 6,8 K DWT) to 50 MW for larger cruise ships (i.e cruise ship LOA 253m, 8K DWT), thereby a total of 70 to 250 battery would be require to impove the efficiency as mentioned in the article.

Look forward to hear your opinions and any additional information you might have on the subject.


View online : Marex article on lng fuel cells:

LNG propulsion


Will shipping enter a new age and become sustainable with LNG propulsion?
My SWOT analysis.

Many studies are published nowadays predicting a new age for shipping. With LNG, shipping would be able to meet the new and future IMO emissions restrictions rules and become sustainable.

LNG is not only environmental friendly; it is also the cheapest fuel available, and this trend is likely to continue due to global reserves. Since Fuel costs represent the majority of shipping lines fixed costs, it seems a no brainer for shipping lines to switch to LNG, reap major savings and obtain an amazing competitive advantage.

At the end of this discussion you will find a link to a very interesting and complete presentation from Wartsila R&D Director dated from 2008, however still very relevant.

To facilitate reading, here is my SWOT analysis on the LNG. In short, you will see that LNG applications are still limited due to space and power constraints. So far LNG only apply to medium speed engines and therefore to small short sea units (ferry, supply, tug, except LNG tanker) , moreover the space required to store the LNG is 4 times bigger, which is at the expense of commercial space, and prevent good payback.

• Main competitive advantage: Lower fuel costs per ton vs. even HFO (same energy content), lower energy consumption (less overall power needed i.e. no need to heat fuel) and lower maintenance costs (machinery)
• Environmentally friendly, cleaner emissions: No Sox, 85% lower Nox, 30% lower CO2
• Higher engine efficiency than HFO engines (+10%)
• Best sustainable shipping solution

• Space for tanks (4 times HFO) main factor limiting application as taking cargo space
• Limited power output. Propulsion only for small units and short sea (ferry, tugs, feeders), except LNG tankers.
• For all other vessel type application so far limited to aux power, eventually quick coastal navigation within IMO emission restrictions zones (payback vs. MDO)
Unburned methane being 30 times more potent grenhouse gaz than CO2
• Investment cost, clarity on payback time since it depends on LNG cost developments
• Restrictive availability/supply and bunkering rules in many ports

• Future tank development reducing space needed
• Two strokes slow engine ongoing developments (Wartsila RT-Flex50 )
• Ship to ship transfer for bunkering
• Increase pressure from society for clean air
• Increase commercial pressure from customers for clean ships/operations
• Further improvement in engines efficiency

• Lack of supply infrastructure?
• LNG price development?
• Long term global economic recession

Wartsila presentation can be found here: http://www.dieselduck.ca/library/05%20environmental/2008%20Wartsila%20propulsion%20alternatives.pdf

View online : Wartsila presentation can be found here:

Fuel efficiency


Maritime technologies fuel efficiency quick guide

The Shipping Efficiency Clean Tech Guide gives an easy to digest scope of the emission reduction technologies available and their associated fuel saving potential.

This is a simplified but comprehensive reference tool to enable rapid assessment of the fuel saving percentages of the main ship efficiency technologies. To be taken with caution, as no doubt some technology potential seems to be over estimated, like solar for instance.

Nevertheless, a useful document to make sense on technology development likelihood (since fuel represent the main part of shipping lines fixed cost), fuel savings being the main driver for any future development.


Nautical chart


OpenSeaMap is an open source free nautical chart. OpenSeaMap is a subproject of OpenStreetMap.

Nautical information as navigation aids, port information, repair shops and chandlerys are incorporated on a map of the world. A user can draw a navigation plan and obtain the waypoints. The chart can also be downloaded to use it on a laptop or PDA without any internet connection.

For safety reasons, the chart should be use with caution, definitely not for commercial navigation.

The chart can be found there: http://www.openseamap.org

View online : OpenSeaMap