By Markus Aarnio, Chief Naval Architect, Foreship
When newbuilding technical specifications are prepared by yards, they are more or less copied from previous projects. But, if working towards the “yard standard” is better for the yard, the same is not so for the owner.
In fact, today, a shipowner’s own policies on sustainability, IMO’s net-zero GHG targets, increasing fuel prices, the longevity of the investment, safety requirements and ICT development - among other factors - mean that the owner needs to pay more attention than ever to specification development. Some items to consider are listed here.
IMO’s GHG targets cannot be met by improving energy efficiency alone; instead, new net-zero, or close to net-zero GHG fuels will need to be phased in very soon. These new fuels will be more expensive than current fuels. This means energy efficiency measures achieve quicker return on investment, but also that energy efficiency measures that were previously considered too expensive should now be considered.
Some examples of items which should be standard in any specification, but are often opposed by yards, are:
- Hull form optimization for the actual operating speed envelope (not trial speed) and correct conditions (not calm water). Often yards insist on optimizing the hull form to contract trial speed only, even if that speed is seldom used in real operation.
- Piping systems and ventilation systems are often designed for available space, all but forgetting energy efficiency. This leads to, for example, high velocities in ventilation ducts. With more attention to proper design, significant improvements could be made.
- Waste heat recovery is standard on every ship, but often this still means exhaust gas boilers / economizers that are too small (often, for “space reasons”). To ensure no energy is wasted, it is essential to have large enough economizers and use all of the “leftover” waste heat in, for example, absorption chillers, steam turbines or heat storage systems.
- Air conditioning is an area which always needs attention. Occupancy-controlled fresh air flow and fan coils in crew cabins will save energy, but these means come nowhere near establishing a standard in shipyard specifications.
- Battery energy storage systems, when designed properly, will improve efficiency and provide other benefits such as improved safety and redundancy. However, these systems are often considered by yards as an additional complication and waste of space.
One way to achieve an energy efficient ship is to specify a contractually binding energy efficiency target. This is not an easy item to negotiate, but it would force yards to study and invest in energy efficiency improvements.
Sustainability in Construction
In the land-based construction business, standards on sustainability are already the norm. There are standards, for example, covering the use of green energy where possible, reducing water consumption, using environmentally responsible materials, and quantifying the environmental impact of the design and construction. All of these also provide starting points for monitoring and improving the environmental footprint of the asset during its lifetime.
These requirements are very seldom found in ship specifications, and it is fair to say that yards will seek compensation to do things that go beyond the rules and regulations. Trying to improve sustainability in construction is thus left for the owner, who will only be able to ensure that particular measures are taken by including them in the specification.
Low Weight Construction
Lower lightweight has several benefits: less gross tonnage, better stability, and a more efficient ship; for these reasons, trying to build lightweight ships was earlier an important aim for yards.
Today, an opposite trend seems to have emerged; one reason may be that easier to build but heavier construction is preferred; another may be that cheaper but heavier materials are now used; a third could be the increased amount of technology onboard. Whatever the reason is, as yards do not seem keen on reducing lightweight of vessels, the owner should consider this in the specification by listing required means of reducing the lightweight. After all, building a heavier than necessary ship has consequences throughout its lifetime. Of course, the owner – and the owner’s designers and architects – should consider weight at all stages of design and construction as well.
Not long ago, yards were happy when the passenger ships that they delivered just about met stability requirements. It was only afterwards, in the next regular lightweight survey, for example, that the owner noticed challenges with stability due to natural lightweight growth.
To be sustainable also means that the ship should work in the future without additional ballasting - whether as fixed ballast, regular ballast or by keeping unnecessarily large amounts of water or fuel onboard.
There are two ways to ensure adequate stability margins will be in place: first, the ship should work properly in all loading conditions, including arrival conditions, without artificial ballasting. Then, a proper growth margin needs to be specified, including both the lightweight increase and vertical center of gravity increase. When these are both in order, stability can work for the lifetime of the vessel, without fixed ballast, sponson-ducktail or other means.
IMO’s target is for shipping to achieve net-zero in GHG emissions by 2050 and many companies and organizations are aiming for net-zero even before 2050. Thus, a ship ordered today must be able to operate with new fuels relatively soon to meet this target. But nobody seems to know what the future fuel for their newbuilding should be. So, to make the decision easier, newbuilding specifications should consider easy conversion to another fuel in the future, if the “winning fuel” is something else than originally chosen. Examples of fuel flexibility could be:
- If LNG is the chosen fuel, the specification should include a means to convert LNG tanks to methanol, with the possibility to increase capacity by utilizing, for example, double bottom below LNG tanks for methanol to maintain the capacity of stored energy. At the newbuilding specification stage this would cost almost nothing.
- If MGO (or HVO, e-diesel or similar) is the chosen fuel, the ship should be designed for the possibility to accommodate methanol as well. This would mean ventilation ducts and systems, tank cofferdams, and similar. These are much easier to arrange for a newbuilding than squeezing them in later during a conversion.
These are just some examples of items which should not be left to the yards to decide. There are many other things, such as passenger and crew comfort, underwater radiated noise or modern ICT systems, for which the yards are more than happy to provide their own “state-of-the-art” solutions in their specification proposals, or even omit completely.