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建立人际资源圈船舶发展的调控措施--论文代写范文
2016-04-26 来源: 51Due教员组 类别: Paper范文
51Due论文代写网精选paper代写范文:“船舶发展的调控措施”。这篇论文主要介绍了船舶发展的调控措施，列举了航运的两个优先主题：有害生物通过船舶压载不必要的转移和禁止使用三丁基锡防污涂料，并对两个主题进行了深入的讨论及分析。
1. Regulative measures under development
The debate considering the need to reduce the environmental burden represented by shipping is at the moment prioritising the topics of:
• Unwanted transfer of harmful organisms by vessels in ballast.
• Prohibiting the use of Tributyltin in antifouling paints.
1.1 Ballast Water Management
The need to monitor and eventually enabling measures to be undertaken to avoid unwanted biological invaders into an area, is one of high priority. The current measure outlined in an IMO guideline (Ass.Res.A868(20)) advice vessels to re-ballast in open sea areas. Two methods, that of sequentially re-ballasting tanks and that of flushing through the tanks, are described. Both operations require depths of more than 500 m and can only be done at a distance of more than 250 nautical miles from shore.
Re-ballasting will incur an increase in power generated represented by additional pumping as well as by the potential need to leave optimum choice of lane.
At present, there are a number of uncertainties related to the future restrictions on ballast water management. Initial investigations reveal that numerous voyages does not represent a particular risk of transferring an unwanted species from one destination to another (DNV, 1999), and hence, there might be no risk reducing potential in requiring these to be re-ballasted or to be treated by any other method for that matter. From this, the obvious measure should be that of considering the risk represented by an actual voyage prior to any required treatment measure to be made. This will also help reducing the potential fuel penalty represented by ballast water requirements.
1.2. Prohibiting Tributyltin in antifouling paints
A proposed ban on the use of Tributyltin (TBT) is currently being discussed within the MEPC.
The introduction of a ban can be implemented as early as year 2003. No new ships will be treated with antifoulings containing TBT after the date of entry into force. A phase-out period of 5 years will ensure that no vessels will be coated with TBT-based products after year 2008.
Tributyltin (TBT) based antifoulings (self-polishing copolymer paints) have since the mid
1970’ provided efficient fouling protection allowing docking intervals of up to 5 years. The proposed ban on these products will result in the adoption of tin-free replacements. There have been consistent claims, in particular from the lobbying interests for tin-products, that these replacements will provide less efficient protection. Hence, the requirement of shorter docking intervals will emerge. Assuming that these products do provide less efficient protection, it is likely to assume further, that the TBT-ban will introduce a GHG-penalty due to the increase of fuel consumption in the period prior to docking.
Replacement products:
Options at present commercially available are:
• Products working on the conventional principle where TBT is replaced by for example Copper.
• Foul release coatings
Most manufacturers have available copper-based products. These are self-polishing paints and tend to indicate performance as good as tin-based products. They function on similar principals, but are more expensive. Copper products can offer the same docking intervals as TBT products.
Low surface energy absorbing surfaces, so called foul release coatings as distinct to antifouling coatings, offer a very smooth surface which fouling find it difficult to stock to. The vessel might foul when stationary, but once moving, the surface will clean itself. Not by self-polishing however, since this provide a non-stick surface. Test results from various manufacturers indicate high performance capability. The non-stick products have a duration considerable longer than the 5-year proposed interval. However, these products do carry considerable costs.
TBT-based antifoulings have proven to provide efficient long lasting protection against fouling allowing docking periods of up to 5 years. The introduction of tin-free substitutes has been attacked on the grounds that these products are inefficient causing fouling earlier in between docking intervals. Some claims have been made suggesting that;
• TBT-free paints require a higher docking frequency (every three years).
• Lacking efficiency leads to higher resistance and thus increased fuel consumption.
• Substitute products are considerably more expensive.
Most of the paint-manufacturers seem to disagree with these claims and are now pushing for the introduction of the ban.
Docking intervals are not only initiated due to the need to renew the antifouling system alone.
Both owner policy as well as operational circumstances may determine another docking frequency pattern. Looking at actual docking frequencies reveal that in fact very few vessels at present (using TBT antifoulings) uses the 5 year window. It is likely that a substitute product will perform satisfactory within actual docking intervals (being closer to three than five years).
The ship resistance through water is sensitive to changes in level of fouling. Insufficient anti-fouling measures will lead to an increase of fuel consumption. This can be seen at a relatively early stage in the fouling process. Fuel penalties associated with hull fouling can reach considerable levels as shown in many case studies. Champ and Seligman (1996) estimated the world-wide annual fuel increase due to an assumed fouling protection deficiency to more that 7 Mton. This represents approximately 5 % of the annual sales of fuel to international shipping and is equal to Singapore’s contribution alone. However, studies addressing this topic, will not provide necessary realism unless they consider the efficiency variations of the range of available substitute products. Furthermore, the likely future increase in efficiency for replacement products should also be included. Most manufacturers offer a range of alternatives and claim that alternatives as good as TBT are available.
Substitute non-TBT products vary in price according to type. In general they are more expensive than the conventional products. A figure of a 20% cost penalty is at present a reasonable estimate. However, the price gap between replacement products and the traditional TBT antifouling has narrowed and is continuing. A larger market will most likely accelerate this trend.
A number of States have already introduced restrictions on the use of TBT-based antifoulings.
In the Table 7-6 below, these are listed. The type of restrictions made and also the number of nations requiring alternatives, suggests that there must be considerable operational experience on these alternatives. Some owners operating ships that never trade in these areas have converted to alternative non TBT products.
Table 7-6 - Overview of restraints concerning the use of TBT
Assuming that TBT is banned and considering actual docking practice and the improvements seen on alternative products both considering their efficiency and their costs, it is unlikely that a fuel consumption penalty will emerge. However, if copper is subsequently banned, there may be some penalties incurring in terms of fuel consumption.
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