Review Reports - Layout Design of the Propulsion Shafting System for a Ship with Multiple Strut Bearings

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Please state acceptable reasons that why FE calculations predict the frequencies higher than these models.? (table 7 & 6).
While frequencies are compared with different models, why don’t the model shapes are compared as well? Then only it is a complete comparison.
Also please give frequency diagram with resonant (mechanical response diagram) of this shaft.
It is also recommended to the authors to get comparison of these models results with experimentation (if not self, please refer to literatures)
Figure 6 & 7, there is no big differences to the strut bearings as appearance in the figures. Please give a clarity.
Equation #7, got some missing info due to formatting.
It is suggested to collect all the notations and nomenclature and present before the introduction section for better reading, including the symbols.
I would recommend to re-write this paper with more evidences of dynamic responses.

Author Response

Please see the attachments (reply of comment)

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The author has written a manuscript entitled "Layout design of the propulsion shafting system for a ship with multi strut bearings". The manuscript still has problems such as unclear innovation points, missing test conditions and conclusions that need to be revised. It is recommended that the author systematically revise the entire manuscript.

1. What is the innovative point of this manuscript? After reading the entire manuscript, it's unclear what its innovative aspects are.
2. Please add relevant references to lines 25-32.
3. Add test conditions to session 3 and explain in detail the rationale for each parameter.
4. What specific effects do bearing span differences have? Provide the basis.
5. In lines 378, what causes whirling vibration? Why is it important? If limited to frames 9 and 11, can FR.10 be considered optimal?
6. Which of the following is considered most important among various bearing arrangements: shafting flexibility, alignment characteristics, and whirling vibration? Why?
7. The conclusion needs revision; it shouldn't be a restatement of the results, but rather a summary of new key points.

Author Response

Please see the attachments (reply of comment)

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

1. Insufficient innovation

(1) The practice of "removing the stern shaft support to enhance flexibility" mentioned in the text has been discussed in existing literature (e.g. Kim et al., 2020).

(2) Using RIN (Reaction effect number) and L/d ratio as evaluation indicators is a conventional practice, lacking new evaluation systems or theoretical breakthroughs.

(3) Although it combines flexibility and vibration analysis, no new coupling analysis method or model has been proposed.

2. Experimental verification is missing

(1) The entire text relies on simulation and theoretical analysis, lacking experimental verification or real ship test data, which affects the reliability and persuasiveness of the conclusion.

(2) For the conclusion of the "optimal layout", there is a lack of comparative verification with existing designs (such as performance comparison with the traditional three-bearing layout).

3. The depth of case analysis is insufficient

(1) Although a certain special type of ship was taken as an example, the representativeness or promotion of this ship type was not explained.

(2) There was no discussion on whether different types of ships (such as large oil tankers and container ships) were applicable to this optimization scheme.

4. Is the model simplification reasonable?

(1) The boundary conditions, mesh density, convergence analysis, etc. of the finite element model were not elaborated in detail in the text, which affected the reproducibility of the results.

(2) The assumption of "ignoring the front stern shaft support" has not been fully demonstrated for its rationality.

5. The fluid-structure coupling effect was not considered in the vibration analysis

The analysis of the vibration response caused by the propeller-hydrodynamic coupling is insufficient, especially under shallow draft conditions.

6. The nonlinear characteristics of the bearing were not discussed

The influences of factors such as bearing clearance, lubrication conditions, and thermal deformation on the dynamic response of the shaft system were not included in the analysis.

7. (1) The format of some references is not standardized:

(2) Some literature lacks page numbers or volume numbers.

(3) Many self-citations:

The previous work of the author Y.G. Kim (such as Reference 18) was cited. Attention should be paid to avoiding excessive self-citation.

(4) Lack of key classic literature:

The classic literature on the theory of shafting alignment (such as M. T. Liao, J. S. Rao, etc.) has not been cited.

8. Grammar and expression issues:

Title and Abstract:

In the English title, "multi strut bearings" is suggested to be changed to "multiple strut bearings", which is more in line with convention.

In the abstract, "whirling vibration responses" is suggested to be clearly "critical whirling speed" or "natural frequency".

(2) Sentence pattern repetition

"The number and position of bearings..." on page 2 It appears twice.

On page 4, "The inverse of the stiffness matrix..." It also recurs.

(3) Inconsistent terminology:

For example, "whirling vibration" is sometimes written as "while ring vibration" (a spelling mistake).

"stern tube bearing" is used interchangeably with "stem tube bearing".

(4) Unclear chart annotations

The units of the coordinate axes and the legend explanations in Figures 10, 11 and 12 are incomplete, which affects understanding.

The modal shape diagram in Figure 13 does not indicate which case it is the result of.

The differentiation of this study lies in: focusing on a specific ship type with a shallow draft and multi-pillar bearings, and proposing an optimization scheme of "removing the stern shaft support + controlling the L/d ratio". However, its innovation is limited and it fails to significantly surpass existing research.