Roll damping sangat berperan penting pada maksimum roll terutama pada daerah resonansi disekitar roll natural period. Dalam prediksi gerak roll, prediksi roll damping dilakukan dengan metode difraksi radiasi yang menambahkan viscous roll damping dari formulasi semi empiris maupun dari uji roll decay. Pada uji roll decay akan didapatkan koefisien komponen roll damping linier dan quadratik yang selanjutnya diperlukan dalam perhitungan nilai roll damping. Nilai koefisien roll damping ini bisa diperoleh dengan melakukan fitting hasil uji roll decay dengan metode Froude maupun Bertin. Pada studi ini dilakukan analisa terhadap perubahan roll damping dan akibatnya terhadap gerak roll pada dua buah model FPU barge yang identik namun berbeda dimensi. Perubahan dimensi model benda apung akan menimbulkan perubahan pula pada karakteristik koefisien linier maupun quadtatik roll dampingnya. Dari hasil pengujian model diketahui bahwa pengurangan dimensi panjang model dengan posisi relatif titik berat dan jarijari girasi roll tetap akan menaikan nilai koefisien roll damping 21% dari desain induknya. Kenaikan nilai koefisien roll damping didominasi oleh komponen linier. Dengan adanya kenaikan koefisien roll damping pada model yang lebih pendek menyebabkan turunnya nilai respon gerak roll melalui uji seakeeping.
Kapal merupakan bagian penting dari kehidupan manusia, terutama dalam bidang transportasi laut. Industri perkapalan di Indonesia telah berkembang dengan pesat, ditandai dengan berdirinya galangan-galangan kapal di Indonesia. Tahap awal dalam proses pembuatan kapal adalah menentukan ukuran dan parameter bentuk kapal. Bersamaan dengan hal tersebut terdapat faktor penting yang berhubungan dengan performa kapal, yaitu tahanan kapal. Kesalahan perhitungan tahanan kapal dapat berdampak buruk terhadap performa kapal dan juga para stakeholder kapal. Salah satu metode statistika yang memungkinkan untuk memprediksi tahanan kapal berdasarkan pengujian tahanan model kapal, yaitu analisis regresi. Pemilihan metode regresi sangat diperlukan karena metode yang tepat akan menghasilkan prediksi yang tepat juga. Pemilihan metode regresi dipengaruhi oleh kondisi data penelitian, seperti terpenuhi atau tidaknya asumsi-asumsi klasik meliputi multikolinieritas, distribusi normal, autokorelasi, dan homoskedastisitas. Hasil pengujian asumsi menunjukan asumsi multikolinieritas dan distribusi normal tidak dapat terpenuhi yang mengarahkan pada penggunaan metode regresi robust ridge.
The development of sea transportation technology is needed to meet the demand for ships that can carry heavier loads and operate at high speeds. Modifications in the form of additional hydrofoil variations were conducted to produce higher lift and reduce the resistance generated by the ship so that the ship can go more efficiently at high speed. This study aims to obtain the effect of adding hydrofoil to ships with variations in the type and shape of foil and find out which types and shapes can reduce resistance on the ship. This research was conducted with several model analysis tests using Computational Fluid Dynamic (CFD) based software, namely Tdyn, at several different speeds. The results of this study show that of the six variation models analyzed, rectangular fully submerged foil models can reduce the total resistance value of the ship by 17.822% from the original ship on Froude Number (Fr) 0.670. The type and shape of the foil is very influential on the lift and resistance produced by the ship.
The development of technology science in the field of maritime is one aspect that needs to be considered. One of them is the development of a propulsion system that is able to work efficiently (Aspects of hydrodynamics) On patrol boats of Indonesian waters guard. Because during this design and manufacture of propellers in need on fast boats is highly dependent on foreign parties. Therefore, the purpose of this study was to produce a propulsion system design suitable with a 60m patrol boat. So that it can be standardized the main size of the boat with its propulsion system. This research is conducted through several stages, where we design the propulsion system and calculated numerically computation (Matlab) Which will be used as a performance analysis of the design that has been determined. So from the results it is known, that the type of propeller boat type 60m patrol match with the engine of the ship that has been set.
Experimental design is a fairly old method of statistically analyzing an experimental prediction. This is used to replace a fairly old system as well, namely in the form of a trial and error method. Because with this method the response results approach from a study can be predicted statistically. In this study, we will calculate some torque values of a propeller on a displacement ship type. Where the ship's operational displacement ship runs on a Froude number below 0.25, for that the Wageningen B-series propeller type is very suitable for this ship. Furthermore, dimensional analysis is carried out with variables that affect propeller performance and uses multivariate combination calculations. The results of the study show the regression equation between the KQ values of the B-series propeller data and the regression formula with the equation Y = 0.9916x + 0.000835 with the value of R2 being 0.9931. so we try to apply an experimental design method to be validated with the polynomial results of the B-series propeller on blades 3 to 6, so that the statistical method of this experimental design is up-to-date in propulsion design calculations.
Twin-screw ship has the advantage of being able to reduce the diameter of propeller by using the same rotation and engine power as a single-screw ship. With the result that twin-screw ship can be operated in areas with lower water depth. However, the type of twin-screw ship has a deficiency in the value of hull efficiency ( ) and the relative rotative efficiency ( ). This occurs because of the propeller position which is far from the field of the flow of the ship’s hull speed (V). So that the value of the water flow to the propeller (advance velocity/) becomes low. Various studies have been conducted to increase wake fraction (w) and reduce the thrust deduction factor (t) values some of which are by modifying the shape of the ship’s stern parts bossing to increase the water speed to the propeller (advance velocity/) which will have a large effect on the wake fraction (w) and thrust deduction factor (t). Among them is by modifying the shape of the ship’s stern bossing so that it can increase the speed of water to the propeller (advance velocity/) which will greatly affect the value of the wake fraction (w) and thrust deduction factor (t) to increase the propulsive coefficient (PC). In this study, it is known that the QPC value for the ship model tested in the Hydrodynamics Laboratory Indonesia (LHI) is 0.54 while for the four models tested using the CFD method is model one 0.63, model two 0.55, model three 0.63, and model four amount 0.51. Based on the above test it can be concluded that the third hull model has the highest QPC. be in ALARP compared to acceptance criteria.
Design and development of propellers for submarines are in some ways different from propellers for surface vessels. The most important demand is low acoustic signature and propeller efficiency. The design for the propulsor for submarine is a specialist task of a later stage of design. The propulsive efficiency has essensially three parts in the traditional method of approach. The first and major part is the efficiency of the propeller it self as a divice which may develop to overcome the resistance to motion the vessel. The aim of this research is to design a mini submarine propeller and obtain high efficiency and low cavitation. To reach this aim, model tests were performed both in Towing Tank and Cavitation Tunnel. From the propeller model tests, the result shows a good efficiency and low cavitation. Keywords: Submarine , Propeller , Efficiency, Cavitation
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