Eko Budi Djatmiko

Neural Network-Based Engine Propeller Matching (NN-EPM) for Trimaran Patrol Ship

In recent years efforts on reducing fuel consumption has become the greatest issue related to energy crisis and global warming. The reduction of fuel consumption can be obtained, if the ship propulsion could be operated in its best performance level. Generally this is done by an appropriate analysis of engine propeller matching (EPM). In this study an EPM based on neural-network method, or NN-EPM, is established to predict the best performance of main engines, leading at minimum fuel oil consumption. A trimaran patrol ship is selected as a case study. This patrol ship is equipped with two 2720 kW main engines each connected to a controllable pitch propeller (CPP) through a reduction gear. The input parameters are ship speed V and service margin SM, with the corresponding output parameters comprise of engine speed nE, engine break horse power PB, propeller pitch P/D, and the fuel consumption FC. An NN-EPM 2-20-15-4 configuration has been constructed out of 100 training data and then validated by 30 testing data. The maximum relative error between results from NN-EPM and EPM analysis is 2.1%, that is in term of the fuel consumption. For other parameters the errors are well below 1.0%. These facts indicate that the use of NN-EPM to predict the main enginess performance for trimaran patrol ship is satisfactory.

Navigation and guidance control system of AUV with trajectory estimation of linear modelling

This paper put forwards a study on the development of navigation and guidance systems for AUV. The restriction in AUV model and estimation on the degree of freedom are recognized as the common problem in AUVs navigation and guidance systems. In this respect a linear model, derived from the linearization using the Jacobian matrix, will be utilized. The so obtained linear model is then estimated by the Ensemble Kalman Filter (EnKF). The implementation of EnKF algorithm on the linear model is carried out by establishing two simulations, namely by generating 300 and 400 ensembles, respectively. The simulations exhibit that the generation of 400 ensembles will give more accurate results in comparison to the generation of 300 ensembles. Furthermore, the best simulation yields the tracking accuracy between the real and simulated trajectories, in translational modes, is in the order of 99.88%, and in rotational modes is in the order of 99.99%.

Analysis of the Adhesiveness and Glue Type Selection in Manufacturing of Bamboo Laminate Composite for Fishing Boat Building Material

The purpose of this study is to select the appropriate high quality-strong-durable type of glue for bamboo laminated composite to substitute Teak wood as an alternative material for fishing boat construction. Tape Test and Pull Off Test according to ASTM D3359 and ASTM D4541 are applied on substrates of Betung laminated bamboo (Dendrocalamus Asper species) in order to determine the strength level of adhesiveness. Four types of glue are applied to bamboo laminated substrate. Having analyzed the experiment results, it indicates that Epoxy Polyamide has the highest adhesion value comparing to others. The Tape Test grades for Epoxy Polyamide are 5A (no glue peeling) and 5B (0% glue chipped extension) as well as the score of Pull Off Test is 7.92 MPa. In terms of construction cost for building fishing boat 20GT (laminated bamboo) using epoxy polyamide is a half compared to Teak wood material.

Analysis on the Critical Conditions of Side-by-Side Offloading Operation between SSP Type-FPSO and Shuttle Tanker

Evaluation is carried out on the operability of a 87,900 ton Sevan Stabilized Platform (SSP) functioned as an FPSO in the hypothetical operational site of Masela Block. This is to observe the critical conditions when side-by-side (SBS) offloading is performed between the SSP and a 35,000 DWT shuttle tanker. The first stage of analysis conducted on the moored SSP as a single floating body indicates the capability to withstand a 100-year wave, designated by the significant height of 8.0 m. Largest motions are experienced when SSP contains 75% load capacity, resulting in the mooring tension range from 2,000 kN up to 7,000 kN, portraying ample safety factors of 2.0 up to 3.0. The second stage of analysis is conducted for execution of SBS offloading from SSP to shuttle tanker, positioned in a 3.3 m distance. Observation is made when SSP is loaded with 100%, 83%, and 75% capacities correlated to the shuttle tanker loading of 10%, 60%, and 90% capacities. This reveals critical conditions arise when the wave exceeds 2.0 m in height, or the operability level of some 88.5%. Safer operation and higher operability level could be achieved by increasing the distance of SSP and shuttle tanker.

Analysis of The Dynamic Stability Positioning Control System of Semisubmersible

The semisubmersible offshore dynamics depend on the condition of the ocean environments. Disruption of forces and moments in the floating structure caused by environment factors, there are wind, waves and ocean currents. This disturbances will cause decreased stability of the structure. This situation will disrupt the process of oil and gas exploration. Currently exploration activities is success if the structure in the static condition and remain on. This condition needs a force or torque to counter the disruption caused by the environment. This paper proposes a control system and analyze the performance of response stability of dynamic positioning system (DPS). DPS will control in 3 Degree of Freedom (DOF) variables, there are: sway, roll and yaw. The structure of the DPS consists of controllers, sensors, actuators. Actuators are Thruster System and Power System. The strategic to maintain in DPS is Linear Quadratic (LQG) control. This method is one of optimal control which capable rejected wave interference. Some values control parameters, that are Q and R in the cost function, show the robustness of DPS.

Analisis Lifting Stability pada Accommodation Barge saat Melakukan Pengangkatan dengan Crawler Crane

Sebuah bangunan apung tidak hanya harus memiliki cukup buoyancy untuk memberi gaya angkat pada struktur terapung tersebut bersama dengan muatannya, tetapi juga harus mampu untuk terapung dengan karakteristik yang baik dan tetap dalam posisi tegak ketika dimuati dengan muatannya. Penting untuk diketahu dan disadari bersama bahwa sebuah kapal atau barge ataupun semua struktur terapung lainnya akan terkena gaya dinamis yang terutama berasal dari gelombang. Interaksi inilah yang menyusun komponen stabilitas sebuah bangunan apung. Makalah ini menyajikan hasil studi numeric terhadap stabilitas sebuah accommodation barge saat melakukan operasi pengangkatan dengan penambahan crawler crane di atasnya. Studi ini dirasa perlu dilakukan karena efek penambahan beban terutama beban yang diangkat akan memberi pengaruh yang cukup signifikan terhadap stabilitas accommodation barge tersebut. Penelitian ini dilakukan dengan membandingkan stabilitas accomodatin barge dalam berbagai loadcase antara lain; lightship, full load, lightship-lifting, dan full-load lifting. Hasil penelitian ini menunjukan bahwa stabilitas untuk semua loadcase yang ditinjau memenuhi kriteria yang diberikan oleh IMO dengan nilai lengan GZ terbesar 4,619 m ( loadcase lightship) dan lengan GZ terkecil 2,481m ( loadcase full load-lifting). Sudut steady heel akibat beban yang diangkat yang terjadi masih di bawah kriteria yang diberikan (<15 0 ), yaitu 1 0 ( loadcase lightship-lifting) dan 1,1 0 ( loadcase full load-lifting ).

Measurement of propeller-induced cavitation noise for ship identification

Acoustic cavitation noise caused by propeller is used in many underwater applications as one of the ships noise signatures. This paper reports characterization process done by measuring the cavitation noise generated by a propeller in a cavitation tunnel. The cavitation tunnel used for the measurement is of the K16B type belonging to the Indonesian Hydrodynamic Laboratory, Surabaya, Indonesia. The experiment is done using a B-series four-blade bronze propeller (diameter 23cm) using a hydrophone placed in the tunnel at window section (60x90)cm2 of the measurement section (400x85x85)cm3. Some of the solutions to get accurate and reliable measurement results include calibration measurement and minimizing acoustic noise system and environment. Preliminary process has been done to analyse the characteristics of the measurement results in the time-frequency domain, with the objective being to detect when and which type of cavitation noise occurs in any kind of condition. Measurement outcomes in the form of acou...