Info Kapal

Ridwan Garcia blog

TERUSAN SUEZ

Mempersingat jarak pelayaran, salah satunya kita memperpendek jarak atau kita melintas alur lewat channal/terusan. para pelaut yg akan keeropa dari asia atau sebaliknya akan melalui terusan suez/suez channal. kalau kita sebut itu adalah terusan malboro..habis gimana tidak 1 ball atau 2 ball rokok jika masuk sana bisa habis sama pandu. dan lagi kalau mau belanja jgn pakai uang lebih yg pas pas saja tukang jualan di sana rada susa sekali ngembalikan kembaliannya aku nulis kebetulan dekat sama tempat kerjaku jadi ada ide buat yg satu ini. sebagai gambaran saja tentang terusan
suez kalau di lihat dari latar belakangnya sbg berikut:

Terusan kapal atau umumnya disebut dengan terusan saja adalah kanal yang digunakan untuk mempercepat pelayaran kapal. Kanal itu sendiri merupakan saluran air buatan. Kanal terdiri dari dua macam, yaitu kanal yang hanya digunakan untuk mengarahkan dan mengalirkan air saja dan satunya adalah kanal yang merupakan jalur transportasi yang dapat dinavigasi, digunakan untuk angkutan barang dan orang, seringkali terhubung dengan sungai, laut dan danau. Tanpa melewati terusan, kapal harus berlayar mengelilingi daratan yang jauh jaraknya. Terusan dapat berupa sungai yang dimodifikasi atau kanal khusus yang dibangun dari awal untuk keperluan tersebut.

Syarat suatu kanal untuk dapat dipakai sebagai terusan adalah kanal tersebut harus memiliki kedalaman minimal 5 m (16,4 kaki. Tujuan dari terusan adalah:
1. Sebagai jalan singkat dan menghindari rute pelayaran yang lebih jauh.
2. Sebagai jalan antara dua buah laut atau danau yang tertutup oleh daratan.
3. Sebagai sarana akses ke lautan bagi kota yang berada jauh di daratan.

banyak pelaut kenal hanya 2 saja yaitu terusan suez panjang 100 mil (160 km), dibuka pada 1869, menghubungkan Laut Tengah ke Laut Merah. dan terusan panama panjang 51 mil (82 km), dibuka pada 1914, menghubungkan Laut Karibia dengan Samudra Pasifik.

karena memang lalulintasnya sangat padat dan sangat di butuhkan buat kapal kapal yg ingin melitas. terusan semacam ini sebenarnya banyak ada:

a.Terusan Laut Putih-Baltik di Rusia, panjang 141 mil (227 km), dibuka pada 1933, sebagian merupakan sungai yang dikonstruksi, kanal buatan dan danau.
b.Terusan Volga-Don di Rusia, panjang 62 mil (100 km), dibuka pada 1952, menghubungkan Laut Hitam, Laut Azov dan Laut Kaspia.
c.Terusan Kiel di Jerman, panjang 60 mil (98 km), dibuka pada 1895, menghubungkan Laut Utara dan Laut Baltik.
d.Terusan Houston di Amerika Serikat, panjang 56 mil (91 km), menghubungkan Houston, Texas dengan Teluk Meksiko.
f.Terusan Alphonse XIII di Spanyol, panjang 53 mil (85 km), dibuka pada 1926, menghubungkan Sevilla dan Teluk Cadiz.
g. Terusan Manchester di Inggris, panjang 35 mil (57 km), dibuka pada 1894, menghubungkan Manchester dengan Laut Irlandia.
h. Terusan Welland di Kanada, panjang 28 mil (45 km), dibuka pada 1931, menghubungkan Laut Erie dengan Danau Ontario.
i.Terusan Saint Lawrence di Kanada dan Amerika Serikat, menghubungkan Montreal dengan Danau Superior.

Sekarang kita kembali ke suez channal/Terusan Suez (bahasa Arab, Qanā al-Suways), di sebelah barat Semenanjung Sinai, merupakan terusan kapal sepanjang 163 km yang terletak di Mesir, menghubungkan Pelabuhan Said (Būr Sa’īd) di Laut Tengah dengan Suez (al-Suways) di Laut Merah.

Terusan Suez dibuka tahun 1870 dan dibangun atas prakarsa insinyur Prancis yang bernama Ferdinand Vicomte de Lesseps.Terusan ini mengizinkan transportasi air dari Eropa ke Asia tanpa mengelilingi Afrika. Sebelum adanya kanal ini, beberapa transportasi dilakukan dengan cara mengosongkan kapal dan membawa barang-barangnya lewat darat antara Laut Tengah dan Laut Merah.
Terusan ini terdiri dari dua bagian, utara dan selatan Danau Great Bitter, menghubungkan Laut Tengah ke Teluk Suez

Coba di kira berapa besar biaya yg akan di keluarkan sebuah kapal jika harus melintasi sepanjang perairan africa. dari segi bahan bakar, running hour dan route pelayaran yg panjang. semua akan berdampak sama cost yg besar. dgn adanya terusan ini akan menguntungkan semua pihak. terutama di pihak perusahaan pelayaran akan bayak diutungkan/save money. walaupun kita nanti ada delay waktu satu atau dua hari berlabuh sebelum masuk ke channal tapi tak akan merugikan terlalu banyak. lagi pula jalan convoy bareng dgn kapal kapal lain juga asik dan menyenangkan.

September 10, 2009 Posted by | Channel | , | 4 Komentar

Buku harian kapal

Sebagai seorang pelaut, jangan melalaikan log book/daily log sheet ini harus di isi dengan baik dan cermat, karena jika terjadi sesuatu di kemudian hari ini yg akan menolong para pelaut. sekedar panduan apa yg di maksud buku harian kapal adalah sbg berikut
Dalam KUHD pasal 348 Nahkoda harus mengusahakan penyelenggaraan buku Harian Kapal . Nahkoda dapat mengerjakan sendiri atau menugaskan seorang awak kapal (Mualim I) tapi tetap dalam pengawasan Nahkoda tentang pengisian dengan benar, lengkap dan berdasarkan peraturan-peraturan.
Nahkoda
Buku Harian merupakan Dokumen yang penting sekali berisi penjabaran perjalanan yang dapat dipercaya dengan catatan yang dipertimbangkan secara seksama dan disusun secara teliti, setiap kejadian dicatat.
kapal yang tidak menyelenggarakan Buku Harian kapal/tidak mempertunjukan buku itu dikenakan sanksi denda sesuai KUHP pasal 562. (Pelanggaran Pelayaran)
Buku ini berfungsi sebagai bahan pembuktian dan merupakan Sumber data bagi Hakim jika terjadi sengketa.
Bagi Pemrintah Buku Harian kapal digunakan untuk alat pengawasan terhadap kapal, nahkoda dan para pelayar.
Walaupun tidak dilarang secara khusus oleh UU : Penyobekan halaman, penambahan halaman, pengosongan halaman, perobahan, penambahan, pencoretan pencatatan tambahan, tidak terbaca isinya, semuanya dapat mengurangi kekuatan pembuktian Buku Harian Kapal.
Kapal yang berukuran isi kotor 500 m3 atau lebih harus menyelenggarakan Buku Harian Kapal dan Buku Harian Mesin, sedangkan kapal yang dilengkapi Radio Telegraphy/Telephony dengan Buku Harian Radio.
Yang harus dicatat dalam Buku Harian Kapal :
– saat buka/tutup pintu kedap air, tingkap-tingkap dan lain-lain.
– Latihan sekoci/kebakaran dan alasan tidak dilakukan latihan.
– Keadaan sumber tenaga darurat.
– Alasan mengapa tidak menolong setelah terima isyarat darurat.
– Sarat kapal saat ditolak.
– Nama nahkoda, perwira dan setiap mutasi yang terjadi.
Di bagian muka Buku Harian Kapal terdapat penunjuk halaman yang memberi keterangan :
– kelahiran dan kematian di kapal
– Mutasi antar awak kapal
– Kecelakaan/kerusakaan yang dialami
– Pengeringan, perbaikan
– Latihan-latihan berkala
– Pembukaan/penutupan pintu kedap air, tingkap.
– Pemuatan muatan berbahaya
– Catatan jumlah pekerja muatan.
Khusus waktu kapal mengalami keadaan luar biasa seperti cuaca buruk, pengisian buku harian kapal harus seteliti mungkin karena akan diperlukan sebagai bahan pembuktian. Jika pihak Asuransi dituntut ganti rugi pihak Kapal (tertanggung) harus dapat membuktikan kerusakan akibat peristiwa laut, bukan karena ketidak naik lautnya kapal tersebut.
Memperlihatkan Buku Harian Kapal
Nahkoda wajb menyerahkan buku harian kapal pada Syahbandar atau Konsul, sedikitnya 6 bulan terakhir. Dirjen Perhub laut menentukan saat-sat mana dan kepada siapa Buku Harian diserahkan :
– Sekurang-kurangnya 1 kali tiap bulan takwin, jika tidak dapat dipenuhi, di tempat pertama yang disinggahi.
– Jika selama 2 bulan takwin berturut-turut dengan alasan yang sah tidak punya kesempatan menyerahkan ditempat pertama.
Tiap pemeriksaan yang dilakukan oleh Syahbandar harus memberikan Eksibitum (pencatatan dengan nomor dan tanggal dokumen) dalam Buku Harian Kapal.

September 8, 2009 Posted by | arsip lama, RESPONSIBLITY | | 8 Komentar

ship Maneuvering system

In the past, ship steering systems were based on gyrocompass measurements to control ship heading. As new measurements become available, as well as the knowledge of advanced nonlinear control techniques, it became possible to perform much more complicated maneuvers by automatic control. This has increased the functionality and reliability of commercially available automatic ship navigation systems. Maneuvering a ship along a desired path is the present challenge.
Ship Steering Systems

Maneuvering a craft, vehicle or vessel means that there are two coupled tasks to be performed to achieve the desired motion. The first is a geometric task stated in terms of a desired curve or path to be followed; the second is a dynamic task given as a desired
speed or, perhaps, acceleration along the path. For a ship in transit, the desired path will be some feasible curve connecting the departure point and the destination. This must be coupled to a dynamic objective which, perhaps, is to keep a constant desired cruise speed or, more advanced, a speed profile along the path constructed by optimizing fuel economy versus time constraints.
History of Automatic Ship Steering
Automatic steering of ships started with the invention of the gyrocompass. Based on the earlier developed gyroscope, Dr. Anschutz-Kaempfe patented the first north-seeking gyrocompass in 1908. This work attracted considerable attention from engineers around the world. In the same year, Elmer Sperry introduced the first ballistic gyrocompass, which was patented in 1911.1,2,3 Soon thereafter, Sperry designed an automatic pilot, the gyropilot, for automatic steering of ships. This was first commercially available in 1922. It had been christened “Metal Mike” by the officers of the ship Moffett. The performance of Metal-Mike seemed uncanny to many because it seemed to have had built into it the intuition of an experienced helmsman.2
The gyropilot, today known as a conventional autopilot, is a single– input, single-output (SISO) control system where the heading, measured by the gyrocompass, is regulated to a desired heading by corrective action of the rudder. In spite of the relatively simple ship model the autopilot controller is based on, it has had great success for many years. However, the introduction of new measurement systems, in particular the global positioning system (GPS), and the need to perform more advanced maneuvers with a ship, motivated creative thinking that opened new possibilities and directions of research. Preeminently, this resulted in dynamic positioning (DP) systems, which were first designed in the 1960s by three decoupled proportional-integral-derivative (PID) controllers.
A DP system is a multiple-input, multiple-output (MIMO) control system where three degrees of freedom (3DOF)-surge, sway and yaw-are controlled by a number of azimuth and tunnel thrusters. The model-based DP controller uses an advanced nonlinear hydrodynamic ship model, derived from first principles, which is simplified to a linear model for almost zero speed applications. Building on the extensive theory generated by the DP research community, the research on ship steering is now going in the direction of high– speed tracking of desired moving position.9 This leads to the theory of maneuvering that, as briefly explained, incorporates a desired feasible path to be followed and a desired speed along it.4,5,6,7
Maneuvering a Ship
In a conventional waypoint tracking system, only the heading is controlled to take the ship from one waypoint to the next, perhaps using a line-of-sight (LOS) algorithm. The easiest way to make this problem into a path following problem is to connect the straightline segments between the waypoints by inscribed circles. Indeed, as pointed out by numerous authors, the shortest distance connecting two points consists of only straight lines and circular arc segments. However, such a path is not feasible for a ship, since at the point where the path switches from a straight line to a circular segment, the desired yaw rate would jump from zero to a non-zero constant. A feasible path (and perhaps optimal in some sense) between two points must be a curve that, in mathematical terms, is at least twice differentiable.
Feasibility of the path is a property of each ship, its minimum turning radius and its dynamic response. Excluding the shape of the path, in the process of control design, the objective in the maneuvering problem is:7
* a geometric task, forcing the ship to converge to and follow the desired path
* a dynamic task, making the ship move at a desired velocity, either determined by a speed profile along the path, or by inputs from the pilot. The desired heading will ideally be pointed along the tangent vector of the path, but it can also be adjusted by an offset to compensate for ocean currents or weather forces in order to facilitate weather optimal maneuvering.

 

Numerous applications arise in this setup: cruising, docking or formation (fleet) maneuvering, to name a few.
Model-Based Control
Since maneuvering means controlling both position and heading (3DOF), present control theory requires that at least three actuators produce force/moment in all degrees of freedom. However, by decomposing the position vectors in the Serret– Frenet frame,4 it is possible to use only the rudder to eliminate the cross-track deviation from the path, as well as to keep the desired heading. The main propeller will independently ensure a desired surge velocity along the path.
Dynamic Ship Model

 

In autopilot designs, usually a linear first or second order Nomoto model1 relating the rudder command to the yaw mode is used with a PID controller to regulate the heading to a reference. In maneuvering applications, the position should also be controlled, and this necessitates a more complex nonlinear model since, as opposed to DP, the simplification to a linear hydrodynamic model of the ship is not valid at higher speeds (except for the special case where the heading and cruise speed are kept constant). In fact, the maneuvering model will include both Coriolis and centripetal forces and nonlinear damping terms.
A general ship model” consists of a kinematics equation and a dynamic equation derived from rigid-body dynamics and hydrodynamic forces. The main complications of this model in high speed are:
* The system inertia matrix is non– symmetrical and depends, among others, on the wave dynamics and frequency of encounter.
* No unified representation of the damping forces has been agreed upon. It is also unclear how to represent shallow water and close boundary effects with respect to this model.
* The mapping between the actuators, that is, the propeller revolutions and pitch angle, the rudder angle, etc., and the forces/moment they produce is special to each ship. Hence, control allocation on a case-by-case basis is necessary.
In addition to these complications, the components form equations given by the kinematics and dynamic equations that are very messy and, therefore, make component form analysis very hard.
If for each desired force/moment vector in surge, sway and yaw there exists an actuator setting that will produce that vector value, then the ship is fully actuated. On the other hand, if there exist force/moment values (within a neighborhood of the operating point) that cannot be produced by the actuator system, then the ship is under actuated. For 3DOF maneuvering, we say, for simplicity, that the ship is fully actuated if it has three or more controls and under-actuated if there are fewer.
Some Proposed Methods
A good method for solving the maneuvering problem for fully actuated ships and vessels has recently been proposed.6 Research on using the same method for under-actuated ships is currently in progress.10 However, solving the maneuvering problem by applying the Serret-Frenet equations11 is also a promising method and has been demonstrated.4,5
 

A reasonable assumption on the dynamic model is that the ship is portstarboard symmetric, which implies that the surge mode is decoupled from the sway and yaw modes. In this case, an independent control system can keep the ship at a constant desired surge velocity by using the main propeller. This implies that the state (velocity) can be treated as a constant in the sway and yaw modes, which is under the assumption that some terms in the mathematics are small compared to others, thus the model becomes a linear parametrically varying (LPV) model. This is the basis for the design in reference 4 (nonlinear maneuvering and control), where the LPV maneuvering model of Davidson and Schiff represents the sway/yaw dynamics. Therefore, the setup is given a desired feasible path, the cross-track and heading deviations are decomposed in the Serret-Frenet frame. Then, the objectives are that the surge velocity is kept constant by some decoupled control system, and the rudder is used to regulate the cross-track deviation to zero while keeping the ship at the desired heading along the path.  

The result is that the under-actuated ship moves along the path with its preferred speed.
In reference 6, the authors presented a nonlinear control design for the second objective, which included an estimator to deal with ocean currents. The model they used was not the Davidson and Schiff model, which was the basis for the design in reference 5. Here, the authors had to resort to both acceleration feedback and output redefinition to solve the same objective. In spite of the preliminary nature of these designs, they both indicate promising ideas towards the goal of a good, robust and reliable maneuvering controller that can be implemented industrially.
Future Challenge
Offshore operators have recently expressed a need for ship and vessel control systems which make it possible to do offshore operations in extreme weather situations. Examples are station-keeping in higher sea states, helicopter landing on ship decks in extreme weather, ROV operations in large waves and robust maneuvering systems in extreme weather. This work must be rooted in both physical modeling, preferably based on first principles, control design and an extensive experimental testing to validate the models and the closed-loop maneuvering performance.12
At present, work is underway to identify and understand the hydrodynamic phenomena that occur in the ship model as sea state increases. Once sufficient ship models have been established and agreed upon, the control engineers need to design robust maneuvering systems that can handle such extreme conditions. Presently, knowledge, we are maneuvering ourselves on the path toward this goal. /st/
rgds

September 7, 2009 Posted by | NAVIGASI | | Tinggalkan komentar