Location Analysis Of Patrol Boat Fin Stabilizer Based On Numerical Method

The fin stabilizer is located on the hull of the ship, one left and one right, which is connected to the fin stabilizer control room as a tool to respond to excessive ship rolling in both directions. In this study, we will analyze the ship resistance due to the addition of a fin stabilizer type Naca 0013 on patrol boats with variations in angles of 0°, 5°, 10°, 15° with speed variations of 25 - 30 knots. Calculation of ship resistance using Maxsurf modeler software and Numeca fine marine. In the early stages of validating the model that has been tested on a towing tank with a patrol boat design made using the Maxsurf modeler and Numeca fine marine. Validation results with a maximum error of 2.38% maxsurf software and 2% Numeca software. There was an increase in resistance due to the fin being installed at an angle of 0° by 0.56% - 1.22%, at an angle of 5° by 2.26% - 3.75%, at an angle of 10° by 6.48% - 9.49%, at an angle of 15° by 13.92% - 18.79 % of the total drag of the ship.


INTRODUCTION
Ship movements at sea basically have three translational motion (surge, sway, and heave) and three rotational motion (roll, pitch, and yaw), which can affect the stability of the ship when sailing due to influences from inside and from outside and to overcome this with the ability of ship motion as one of the crucial aspects related to shipping movement in response to the influence of external forces acting on the ship [1]. In improving the quality of maneuvering on ships, the use of an anti-roll system on ships is able to affect the response of rolling motion on ships. One of the anti-roll systems is the fin stabilizer. There are several ways to increase stability and reduce appendages resistance ship by varying the slope angle and fin-type from NACA 0012 and NACA 0018. [2] as well as controlling the tilt angle with a control system with several methods such as the Sugeno-Takagi fuzzy logic method [3], Adaptive Fuzzy [1] [4] and MATLAB LMI [5] model predictive control [6], PID control system with RBF neural network [7], software package ANSYS AQWA [8].
Based on Global Marine Technology Trends, GMTT 2030 on Energy Management, various studies have been conducted to save energy from fossils either by seeking alternative energy [9] reduce exhaust  [10], reduce ship drag such as optimization of bulbous bow and axe bow [11], and increase propeller efficiency [12] and fin stabilizer [13] Research based on the location of placement and ratio of fins was carried out on NACA 0018 fins mounted on the bow of the ship to find the effect of fin action at various angles of attack and get the best resistance by using a model test in the towing tank and compared with computer simulations from the simulation results to get the lowest resistance. at an angle of 5° [2]   Hull resistance without fins, with fins at d=0 degree and d=+/-15 degree [14].
Research on ships without fins and using fins with an angle of attack ± 15° has a significant effect on the total resistance of the boat as shown in Figure 2 shows the ship resistance based on simulation data and towing tanks where the simulation results show good agreement with experimental data, the difference in ship resistance is lower than 2% when the fin is not deflected (d=0 degrees), while when the fin is deflected by d=+/-15 degrees, the drag increases by about 17.5% compared to when the angle of attack is 0 [14].
Ship stability is one that is very important for the comfort and safety of the crew, especially on warships equipped with weapons so that in firing weapons, the results are better. One of the ship's antiroll tools is the Fin stabilizer which is installed on the right and left hulls of the boat, but the addition of a fin stabilizer can provide additional ship resistance. Further analysis of ship resistance by using models in towing tanks and using simulation software. This study uses Numeca fine marine simulation software with patrol boat objects with the following data:

Research Methods
In a comparative method study, the authors compare the results of the modeling of ship resistance on the patrol ship model before installing the fins on the towing tank with the results of the Numeca fine marine simulation with a maximum error of 3%. Next will make a simulation of the patrol boat after the fin is installed to find out the addition of ship resistance with variations in ship speed 25 -30 knots with variations in the angle of attack of the stabilizer fin 0°, 5°, 10°, 15°.in the Parasolid "x_t" format. The schematic of the modeling process is as follows.

The design process and 3D models
The simulation process in CFD software starts from making a hull model designed from Maxsurf Modeler based on the lines plan and test model on the towing tank, then exported to the IGES program to change the ship model into a solid form. The ship model consisting of surfaces is made into a tight closed-form to become a solid object. The following solid model is made with Rhinoceros; besides that, Rhinoceros is used to change the shape of the surface so that it can be moved in the Parasolid "x_t" format. The schematic of the modeling process is as follows:

Selection of Number of Grids (Meshing) and Simulation Model
A grid is defined as a collection of elements that combine to form a specific shape. The determination of the number of grids used in ship modeling affects the level of accuracy of the model. The smaller the size of the grid used, the more the number of grids used, and it will take a long time to perform the simulation. The small grid size will affect the level of smoothness of each part of the hull. The use of a grid size that is too large will also affect the shape of the hull that will be produced to reduce the results obtained, so it is necessary to carry out a process to get the optimum number of grids. The number of grids used in ship modeling with Numeca Software is determined based on modeling experiments with various variations in the number of grids which are then optimized to obtain the optimum number of grids. The optimum number of grids is the number of grids used does not affect the magnitude of the results accepted.

Model Verification and Validation
The verification and validation of the model aim to check whether the developed model has presented the expected conditions; besides that, it is also a comparison between the needs of the tested model and the patrol boat design that was made using a maxsurf modeler with Numeca software in accordance with a maximum error of 3%. Then proceed with making the geometry of the selected fintype using data according to the NACA standard and combined with a ship model that has been validated using the Rhinoceros software and Numeca Software for research to analyze the effect of adding fins to ship resistance

Model Verification and Validation
From the results of model tests and simulations, it is found that the comparison of ship resistance between the model conditions that have been tested and the patrol boat design made using the Maxsurf modeler with a maximum error of 2.38% and the Numeca fine marine software with a maximum error of 2%. Model verification and validation include model unit test, resistance test,

Model simulation with fin stabilizer
After creating a validated ship model, then proceed with making the geometry of the selected fintype using data according to NACA standards and combining it with a validated ship model using Rhinoceros and Numeca Software. Selection of fin stabilizer with a model according to Naca foil to be tested for locations below the waterline, at coordinates X = 24 m, y = 0 m, and Z = 1 m with variations in ship speed from 25 -30 knots with variations in the angle of attack of Fin stabilizer 0 °,5°, 10°, 15°.  Figure 6 at a speed of 25 knots with a fin attack angle of 0°, the ship's resistance is 140.358 kN, in half body simulation conditions so that the actual resistance is 2 x 140.358 kN = 280.716 kN, from these results to determine the amount of resistance caused by the addition of the fin. It can be obtained by reducing the data before there is a fin at the same speed so that we get 280.716 kN -279.156 kN = 1.56 kN or 0.56% of the total ship resistance. The complete simulation result data is shown in table 2    software in table 3, data obtained at the shipping speed from 25 knots -30 knots at an angle of 0° an increase in resistance of 0.56% -1.21% of the total resistance of the ship, at an angle of 5° an additional resistance of 2.26% -3.75% of the total resistance of the boat, at an angle of 10° there is an increase in resistance of 6.48% -9.49% of the total resistance of the ship, at an angle of 15° there is an increase in resistance of 13.92% -18.79% of the total resistance of the boat. The higher the speed of the ship and the angle of the stabilizer fin, the more the additional resistance of the boat increases.

Conclusion
A fin stabilizer is one of the anti-roll systems that can affect the excessive rolling response of the ship in both directions. Installation of fins, in addition to having a positive impact, can have a negative effect on the form of an increase in ship resistance. In foil naca type 0013 at a ship speed of 25 knots -30 knots, the data on the rise in ship resistance is obtained as follows: at an angle of 0°, there is an increase in resistance of 0.56% -1.21%, at an angle of 5° there is an increase in ship resistance of 2, 26% -3.75%, at an angle of 0°, angle of 10° an increase in resistance of 6.48% -9.49%, at an angle of 15° an increase in resistance of 13.92% -18.79% of the total resistance boat. From the results of this study, when compared with research from Della Rosa, it is almost the same wherein his research mentions the fin stabilizer with an angle of attack of 0° there is an increase in ship resistance of less than 2% and at an angle of attack of 15° by 17.5% of the total ship resistance.

FIN RESISTANCE
Implementation of the use of fin stabilizer and variations in the angle of attack depending on the size of the external force caused by sea waves and the control of the angle of the fin stabilizer has been integrated with the control system so that the use of the fin stabilizer is more effective. At the next research stage, research can be carried out by varying the type of foil and fin shape to get the best ship resistance and anti-roll