Estimation of Maneuverability of Trawl Fishing Vessel Using an Analytical Method

Round 1

Reviewer 1 Report

General comments

The work refers to a very important matter for both performance and safety of fishing vessels. A revision of the text is needed. The explanation is often difficult to understand for both poor English language and confusion in the text. In some case the reporting of the whole development process generates confusion. The database is not homogeneous, there are too many disturbing factors affecting the comparison on which the work is based. The mathematical part of the work is interesting and the detailed formulation of manoeuvring is sound.

A major revision is suggested.

Line 15 A very influencing (and different from commercial ship) factor could be B/T also and should be mentioned

Line 19 Change “on” with “to”

Line 19-20-21 It is not clear; “parameters” in line 21 has to be deleted?

Line 20 “only” could be deleted

Line 23 “modified empirical formulas” seems not a keyword

Line 29 Add “and to” before “chemical”

Line 36 Why this comparison should be done? Please explain

Line 42 The mentioned formula should be reported or referred

Line 117 Empirical formulas are not analytical, there is some confusion

Line 150 This conclusion is obvious

Line 197-200 It is repeated what said at 185-190

Line 228 How?

Line 237 From the reported values it appears that the work is limited to large, offshore fishing vessels this should be mentioned

Line 256 and following. The difference between Sea trial test and Kijima’s data is very large. This poses some doubts about the scientific soundness of choosing such formulas as the basis for modification to get a new formula.

This comment can be reported to the further mentioned tests too

Line 280-281 This is a weak point of the work. More significant is the fact that the length is very close to the limit of 100m.

Line 410-418 This comments are obvious and could be deleted

Line 423-433 There is confusion between the effect of the hull form (impossible to evaluate here) and the effect of the rudder. Further confusion is given considering different types of rudders. As this work is based on comparison, this has to be performed on few and homogeneous items.

Line 453 “The maneuverability of most fishing vessels at their design stage is estimated with empirical formulas as part of an analytical method, which reduces the price of ship construction and expedite launching by decreasing the tie and cost required for the estimation process.” It is very difficult to see this connection.  “Expedite” should be “expedites”.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The paper addresses the maneuverability of trawl fishery vessels, in the design stage, using an analytical method. In a previous study, the authors of this paper derived a modified empirical formula by adding the hull form parameters of trawl fishery vessels to the existing empirical formula based on those of merchant ships. The paper analyzes the validity of the previously derived modified empirical formula, by authors, by applying data from the newly-built training vessel that has the hull form of a trawl fishery vessel.

Some minor clarifications are needed and some recommendations for improvements are given below.

1. General: usually according to the FAO (http://www.fao.org/fishery/vesseltype/10/en ) the used term is “Trawler” for “Trawl Fishery Vessel”. Alternatively, the term could be “Fishing Trawler” or “Trawl Fishing Vessel”.
2. Line 44: What does coefficient stans for ???/?? Probably comma is missing i.e. ??, ?/?. Maybe this could be considered as a sole coefficient but since in the eq. (7) we have separated ??, ?/?, and ? maybe it is better to quote all of them separately.
3. Line 64: It is not common to write “et al.’s”, just “et al.”.
4. Line 66: Statement “In this paper, we use Kijima et al.’s (1990) empirical formula and our modified empirical formula to perform turning motion and z-test simulations, which constitute part of the IMO maneuverability assessment on a training vessel with a trawl fishery vessel’s hull form built in 2020.” and line 141, Table 1; =>The merchant ships used for the empirical formula are built not later than 1990 that is now, for more than 30 years. For validating the Kijima et al. empirical formula it would be better to validate it in two steps, first to add the new merchant ships, and then new trawlers. In this sense, we are somehow comparing apples and oranges. Finally, the empirical formula is validated, due to lack of data, just on one model test.
5. Line 130: Statement “It was also verified by comparing the simulated trajectories of turning motions that including the shape of the stern as an additional consideration to the equation could reduce the accuracy in estimating the maneuverability of fishing vessels’ hull form, Therefore, the authors of this study determined that the version of Kijima et al.’s (1990) empirical formula without considerations for the stern shape is more suitable for estimating the maneuverability of fishing vessels’ hull form.” is a little bit odd. The stern shape is very important for maneuverability, a so is the rudder area as the authors have concluded. The propulsion type either. For better maneuverability, the trawlers usually have two propellers system.
6. Line 179: Table 2, it is suggested adding a year of newbuilding.
7. Since it is very difficult to base conclusions on the large merchant ships, the mass (displacement) of ships should be used somehow in the equations for the comparison, because of their mass, tankers have large inertia (and other merchant ships), making them very difficult to steer. A loaded supertanker could take as much as 4 to 8 kilometers and 15 minutes to come to a full stop and has a turning diameter of about 2 kilometers.
8. From Fig. 2-Fig. 4 one can conclude (comparison shows) that the trawl fishery vessels are placed as a particular separate group of points, so is again very difficult to make conclusions based on the merchant ships. The statement in line 46 “The accuracy of estimation, however, may vary depending on the similarity of hull forms between the target ship and merchant ships.” is correct, but can we talk about similarities of these two types of hull forms?
9. Line 363: Stated IMO criteria stands for what type of ships?
10. Authors are encouraged to better explain the validation process performed in the paper and obtained results.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Dear Authors,

thanks for your valid contribution. No special suggestions are proposed from my side. Results are interesting and I hope to have the pleasure to review a new extention of your work soon. Maybe, you could include a Nomenclature at the end in the way to support the quick/clear comprehension of formulas.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf