Measurement of residual deviations of the ship’s hull axis from the initial positio

The article discusses a method for measuring deviations of the deformed axis of a ship’s hull form the initial (non deformed) position that arise with a general residual bend or deflection. The Rules of the Russian Classification Society (RCS) and the Rules of the Russian Maritime Register of Shipping (RMRS) do not have standards for assessing the main characteristics of such deformations (the maximum bend of deflection arrow). Nevertheless, this defect has a significant impact on the overall strength and reliability of the ship’s hull in operation and can cause sudden failure. The presence of general residual deformations of the hull not only negatively affects the strength and reliability of the hull, but also complicated cargo operations and leads to errors in determining the amount of cargo in the tanks of tankers. The result of the research presented in this article is a new technique for measuring deviations of the hull axis of a ship with general residual deformations from its initial nondeformed state, mathematical dependencies for calculating the exact coordinates of the deformed hull axis. This will make it possible to more accurately assess the level of overall strength of the hull, and, if necessary, develop a technological process for elimination the overall residual bend (deflection). The procedure for determining the parameters of general residual deformations is further complicated by the fact that the maximum inflection (deflection) arrow obtained from the measurement results also includes an elastic component. The developed mathematical dependencies make it possible to exclude from the maximum arrow of bend (deflection) obtained as a result of measurements the elastic component caused by the load acting on the ship’s hull. A device has been developed for recording deviations of the axis of a deformed ship’s hull from the initial (nondeformed) position. The new measurement technique and this device will allow measurements not only when the vessel is on a slip or in a dock, but also afloat at quay wall. Due to the fact that the geometric characteristics of the section along the length of the ship’s hull change, the optimal number of measured sections (5–7) in the area of the cylindrical insert is justified, with the length of each section a multiple of the frame spacing. An example is given of calculating the ordinates of the residual curved axis of the body based on the measurement results and determining the curvature in each of the deformed sections.

1. Karklina, T. O. Technological methods for stabilizing the metrological characteristics of tankers. PhD diss. SPb: SPGUVK. 1991.

2. Baryshnikov, S. O., Karklina, T. O. “Genera residual deformations of ship hulls.” Vestnik INZHEKONa. Seria: Tekhnicheskiye nauki 8 (2010): 124‒128.

3. Baryshnikov, S. O., Karklina, T. O., Chistov, V. B. “Reliability of ship hulls with general residual deformations.” Vestnik Gosudarstvennogo universiteta morskogo i rechnogo flota imeni admirala S. O. Makarova 11.3 (2019): 519‒533. DOI: 10.21821/2309-5180-2019-11-3-519-533.

4. Karklina, T. O., Pavlov, A. V. and Chistov, V. B. “Improving the accuracy of measuring the residual bend of the ship’s hull.” Vestnik Gosudarstvennogo universiteta morskogo i rechnogo flota imeni admirala S. O. Makarova 4(32) (2015): 109‒118.

5. Boytsov G. V. “Analysis of possible causes of the appearance of general residual deformations of the hull” // Otchet po dogovoru № TSRP 05–31–07/ ruk. d. t.n., professor G. V. Boytsov. — SPb. 2005. — 48 s.

6. Boytsov, G.V., Aleksandrov, A.V., Ankudinov, O.S. “Analysis and assessment of residual deformations of the hulls of mixed navigation vessels with reduced stability margins of their longitudinal framing.” Trudy tsentral’nogo nauchnoissledovatel’skogo instituta im. Akademika A. N. Krylova 28 (2006): 16‒23.

7. Boytsov, G. V., Paliy O. M., Postnov, V. A., Chuvikovskiy, V. S. Handbook of ship structural mechanics. Leningrad: Izdvo Sudostroyeniye. 1982.

8. Baryshnikov, S. O., Karklina, T.O., Chistov, V.B. RU 2 435 149 C1, IPC G 01 M 5/60. A method for determining the residual total bending of a ship’s hull. Russian Federation, assignee. Publ. 27 October 2011.

9. Technological instruction for eliminating residual bending of ship hull’s. / FGOU VPO SPGUVK / ruk. S. O. Baryshnikov, otv. isp.: T. O. Karklina, V. B. Chistov. Soglasov. FGU Rossiyskiy Rachnoy Registr. Pis’mo 07–06–450 ot 21.02.2012. — SPb. 2011. — 201 s.

10. Baryshnikov, S. O. Scientific basis of technology for restoring the overall strength of a ship’s hull during repairs. Grand PhD diss. Astrakhan’: AGTU, 2011.

11. Baryshnikov, S. O., Pogodayev, L. I., Chistov, V. B. Reliability of mechanisms and ship hulls. SPb.: Izd-vo GUMRF im. Admiral S. O. Makarova. 2018.

12. Girin, S. N., Kuznetsova, T. A. “Elastoplastic deformation of the ship’s hull under loads close to the maximum.” Trudy Krylovskogo gosudarstvennogo nauchnogo tsentra Spetsvypusk 2. (2018): 33‒40. DOI: 10.24937/2542-2324-2018-2-S-I33-40.

13. Girin, S. N., Isaeva, T. A. “Limit state of a compressed-bent rib of a ship’s hull.” Trudy Krylovskogo gosudarstvennogo nauchnogo tsentra Spetsvypusk 1. (2020): 24‒29. DOI: 10.24937/2542-2324-2020-1-S-I24-27.

14. Boytsov, G. V. ”Development of proposals and design dependencies to take into account residual deflections (bend) when calculating the overall strength, as well as measures to limit their occurrence”/ Contract report № TSRP05–31–07 (etap2). ruk. d. t.n., professor G. V. Boytsov. — SPb, 2005. — 56 s.

15. Bimberekov, P. A. RU 2 298 162 C1, IPC G 01 M 5/00. Method for determining the general residual deformations of the hulls of transport and/or parking vessels Russian Federation, assignee. Publ. 27 April 2007.

16. Ulasov, A. M. and Burmistrov, E.G. “Method of probabilistic assessment of the residual life of a ship’s hull and it’s elements.” Rechnoy transport (XXI vek) 2 (2021): 44‒48.

17. Girin, S. N “Standartization of residual bends of ship hulls. Justification of the restrictions introduced by the River Register on the value of maximum residual deformations of the general bending of ship hulls”/ Contract report № 143/17/31/09/1701/VGUVT ruk. D.t.n., prof. S. N. Girin. — N.Novgorod, 2018. — 79 s.