Speed Optimization in Bulk Carriers: A Weather-Sensitive Approach for Reducing Fuel Consumption
Round 1
Reviewer 1 Report
Dear Authors,
Your manuscript addresses interesting areas of scientific research, but after carefully reviewing it, I have the following suggestions and questions:
1. The genetic algorithm has not been described clearly and comprehensively. What is the method of selection, crossover and mutation probability? Some pseudo-codes of the implemented methods could help to understand the algorithm.
2.The results obtained using GA should be compared with other methods, and on this background the Authors should point out the advantage of the presented approach.
3. What is the performance of the developed algorithm? How much was the computational time and what does it depend on?
4. Figure 3 should be expanded and presented with more attention to aesthetics.
5. Fig. 4 shows the linear relationship between speed and fuel consumption. This should be compared with the results of other studies in the literature.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper presents a Speed Optimization procedures for Bulk Carriers to reduce the fuel consumption. The paper is interesting but I have some comments as follows:
1. The abstract can be more detailed than this version.
2. While the authors considered the paper that are related to bulk carrier, however, as they are dealing with ship routing problems, more papers must be considered showing the different types of ships as well as the methods used; for instance there are many related to container ships.
3. It is not clear if the authors transform the weather conditions to fuel consumption, or they calculate the total ship resistance and then based on the results, the fuel consumption is computed; please define in the manuscript.
4. Based on the previous point, the method must be improved and detailed.
5. please mention the country along the route.
6. If the authors can present the route on a map, it will be clear to the readers.
7. The authors mention an improvement by around 2.5%; please compare your results with the previous papers published and comment on that.
8. The conclusion must be improved.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The article related to the problem of optimizing the speed of in bulk carriers in terms of reducing fuel consumption depending on weather conditions is an interesting attempt to solve the problem of optimizing fuel consumption on a given route.
The topic of the article is current and interesting for the Marine industry
The structure of the article is correct.
It is proposed to consider the following modifications to the study:
1. Specifying the abstract description taking into account the obtained results.
2. Moving the Abbreviation / Parameters table to the beginning of the article.
3. The presented fuel consumption model seems to be based on a specific degree of engine load (e.g. 100%) - does it take into account intermediate degrees of engine load, e.g. at partial deflection of the control devices?
This may be important in the case of vessel speed control, and may imply different SFOC values ​​(with different control lines -% of engine load/drive, engine/propeller speed). Has this aspect been taken into account in the model?
4. Figure 2 - refers to the specific draft/loading of the ship. The ship's draft/ load, which is one of the important elements affecting the ship's speed and fuel consumption, is not taken into account here.
5. The criteria for the impact of the number of BNs on fuel consumption are not entirely clear - how do the individual Scenarios correspond to the information contained in Figure 2 ? This requires explanation - on the basis of which the criteria were adopted for scenarios 1-4.
4. The conclusions section should be described in more detail, including the specific results obtained.
The results presented in the article are based on a methodology that requires deeper correction or explanation of the aspects mentioned in the above points
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
The article may be of interest to people who forecast fuel consumption, and especially to people who optimize ship motion parameters in order to reduce total fuel consumption. The topic is widely known. The given way to solve the problem is very simple. It applies to a ship's journey only between two ports, on a known route. Optimization involves taking into account the sea state expressed in Beaufort degrees, which affects the total hull resistance and, in the final stage, fuel consumption. Unfortunately, the force and direction of the wind are not taken into account, which may affect the change in total resistance by -10% to +10%, which causes a greater change in fuel consumption than the fuel consumption specified in the study. Since the authors take into account two factors, it would be advisable to determine the profits for each separately. Specific fuel consumption was approximated by straight line sections for step changes in engine load. No data for this engine or characteristics of this SFC were provided. No data from the engine manufacturer or experimental data for a specific ship.
The change in hull resistance with its fouling process is not taken into account. Do the authors assume that the hull is always clean? The growth of the hull changes the resistance characteristics, and its change may have an impact on optimizing the ship's speed at individual wet points.
This substantially limits the applicability of the results obtained to a real ship. It should be emphasized that the basic measure to reduce total fuel consumption for travel between selected ports will always be to reduce the ship's speed, which leads to an increase in the ship's stay at sea and other types of costs.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Dear Authors,
All my concerns have been addressed, so I recommend publishing the manuscript.
Reviewer 2 Report
Ok from my side
Reviewer 3 Report
Thank you for responding to the comments in the review. The changes and modifications made to the text and charts allow, in my opinion, the substantive classification of the article for publication in the MDPI journal without further substantive changes.
