Ship Draft Research Articles

PERENCANAAN KONSTRUKSI BETON SLIPWAY - 150 LWT

Budhi Dharma, in paper Construction Planning of Slipway - 150 LWT Concrete explain that in shipyard planning major facility types shipyard slipway suitable transverse system was built in the open or closed.To ship with 150 tons LWT according to the register BKI got main dimension vessels = 34 meters LOA,30 meters LP, 6 meters B, the ship draft T = 2,2 meters, and empty vessel draft Tk = 1,18 meters and block coefficient = 0,68.Of the main dimension of the vessel were then long slipway, heavy lorries and heavy lorries transfer launchers after the total weight is obtained the dimensions of the placement of concrete beam rail and lorry.Keyword : Slip way and structure concrete

Analytical bow waves for fine ship bows with rake and flare

The bow wave generated by a steadily advancing ship is considered for a family of fine ruled ship bows with rake and flare. This family of ship bows is defined in terms of four parameters: the ship draft D, the entrance angles a and a' at the top and bottom waterlines, and the rake angle 8. The corresponding bow wave similarly depends on four parameters: the draft-based Froude number F and the three angles a, a', and 8. An extensive parametric study, based on thin-ship theory, is performed to explore the variations of the water height Z0 at the ship stem X = 0, the location X0 (measured from the ship stem) of the intersection of the bow-wave profile with the mean free-surface plane Z = 0, and the bow-wave profile, with respect to the four parameters F, a, a', and 8. This parametric study extends the previously reported similar study of the height Zb of the bow wave and the location Xb of the bow-wave crest. These two complementary parametric studies yield simple analytical relations, which extend relations given previously for wedge-shaped ship bows without rake or flare. In spite of their remarkable simplicity, the analytical relations given here yield bow waves that are comparable to computational fluid dynamics (CFD) waves given by Euler-flow calculations. The analytical relations, which explicitly account for the influence of the four primary parameters F, a, a', and 8, can be used immediately—without hydrodynamic calculations—for ship design, notably at early design stages when the precise hull geometry is not yet known. The study also provides insight for ship bow design. Specifically, it suggests that a bow with positive rake and negative flare may be beneficial, and that a bulb located aft of the stem and integrated with the hull may be an advantageous alternative to a traditional bulb protruding ahead of the bow, in agreement with the results of a hull-form optimization analysis.

Long-Term Evolution of Columbia River Tides

A 170 km tidal channel connects the lower Columbia River ports of Portland and Vancouver to the Pacific Ocean. An increasing incidence of low water levels during summer and fall sometimes limits the draft of ships using the channel and can delay transits. Reduced spring freshet water levels have also decreased shallow-water habitat for juvenile salmon. Records from Tongue Point (km-30, 1925-date), and Vancouver (km-175, 1902-date) were used to analyze historic changes. Mean water levels (MWL) at Vancouver have dropped ∼0.3–1.5 m since 1902, depending on flow. Lower low water (LLW) at the lowest river flows has decreased ∼0.4–0.5 m since 1940. Vancouver LLW has dropped more than MWL and higher high water (HHW), increasing tidal range. Tides in the Columbia and many other river ports are evolving because of a combination of changing ocean tides and local alterations, including both harbor development and river-flow modification. Assessments of climate change impacts on harbors need to consider both factors.

Hydrodynamics of a ship/whale collision

All endangered large whale species are vulnerable to collisions with large ships; and “ship strikes” are the greatest known threat to one of the world's rarest whales, the North Atlantic right whale ( Eubalaena glacialis). The magnitude of this threat is likely to increase as maritime commerce expands. Factors influencing the incidence and severity of ship strikes are not well understood, although vessel speed appears to be a strong contributor. The purpose of this study was to characterize the hydrodynamic effects near a moving hull that may cause a whale to be drawn to or repelled from the hull, and to assess the accelerations exerted on a whale at the time of impact. Using scale models of a container ship and a right whale in experimental flow tanks, we assessed hydrodynamic effects and measured accelerations experienced by the whale model in the presence of a moving vessel. Accelerations at impact were measured while the whale was at the surface, for various vessel speeds, orientations of the whale relative to the vessel path, and distances off the direct path of the vessel. Accelerations experienced by the whale model in a collision: increased in magnitude with increasing ship speed; were not dependent on whale orientation to the vessel path; and decreased exponentially with increasing separation distances from the ship track. Subsequent experiments with the whale model submerged at one to two times the ship's draft indicated a pronounced propeller suction effect, a drawing of the whale toward the hull, and increased probability of propeller strikes resulting from this class of encounter. Measured accelerations are a proxy for impact severity, but do not constitute a detailed study of injury mechanism in a living animal, though they may help inform future work. We present a heuristic map of the hydrodynamic field around a transiting hull likely involved in close whale/vessel encounters. These results may have bearing on policy decisions, particularly those involving vessel speed, aimed at protecting large whales from ship strikes worldwide.

Ship‐based measurements of sea surface topography

By equipping the research vessel Kilo Moana with a geodetic GPS receiver and a radar water level gauge, and using a kinematic GPS processing package, accurate 1 Hz estimates of the sea surface height were obtained. Geodetic positioning of ocean‐platforms using only the GPS system cannot account for changes in the draft of the platform. This is especially problematic for ships, where changes in the load, speed and/or ocean density can change the ship's draft by 10s of centimeters. By installing a radar gauge this noise source can be removed from the estimates of the sea surface height. We envision that this technology could routinely provide high resolution information on the geoid, or the variation of the sea surface height, including sea‐state, from an existing reference geoid.

Studies on Resonant Water Motion Between a Ship and a Fixed Terminal in Shallow Water

This work focuses on the hydrodynamical problem of a Liquid Natural Gas (LNG) carrier near a Gravity Based Structure (GBS) -type offshore terminal subject to incoming waves in medium deep to shallow water conditions. The work is restricted to 2D, and the ship is restrained from moving. The resonant behavior of the fluid in the gap between the ship and the terminal is investigated. The problem is investigated by means of a numerical model and model tests. Potential theory is assumed, and a linear as well as a nonlinear time-domain numerical wavetank based on a boundary element method with a mixed Eulerian–Lagrangian approach is implemented for this purpose. Model tests (near 2D) of a midship section near a vertical wall are carried out in a 26.5m long and 0.595m wide wave flume in model scale 1:70. In full scale the ship beam is 45m and the ship draft is 12m. The ship model is constructed in such a way as to avoid flow separation, i.e., no sharp corners. Several parameters are varied: water depth, wave period, and wave steepness. Wave elevation is measured at 12 locations.

Modelling of Ship's Draught Measurement Error for Safety Underkeel Clearance Determination

Modelling of Ship's Draught Measurement Error for Safety Underkeel Clearance Determination In the article expert research result are presented concerning ship's draught measurement error. The questionnaire was carried out in the group of navigation experts and used for building the model of ship's draught determination error. The results are implied in model for safety underkeel clearance determination.

Determination of Dynamic Under Keel Clearance of Maneuvering Ship

Determination of Dynamic Under Keel Clearance of Maneuvering Ship The safety of navigation of a ship manoeuvring within port waters mainly depends on its under keel clearance (UKC). Mainly UKC depends on water level change, squatting of moving ship and heeling and wave response. The effect of these components will be determined currently than such UKC is called as dynamic under keel clearance. The paper presents an analysis of certain components of UKC to maximise of ship draft and thus to achieve the economic benefit to port and ships owner.

Modeling Energy Use and Emissions from North American Shipping: Application of the Ship Traffic, Energy, and Environment Model

The waterway network ship traffic, energy, and environment model (STEEM) is applied to geographically characterize energy use and emissions for interport ship movement for North America, including the United States, Canada, and Mexico. STEEM advances existing approaches by (i) estimating emissions for large regions on the basis of nearly complete data describing historical ship movements, attributes, and operating profiles of individual ships, (ii) solving distances on an empirical waterway network for each pair of ports considering ship draft and width constraints, and (iii) allocating emissions on the basis of the most probable routes. We estimate that the 172 000 ship voyages to and from North American ports in 2002 consumed about 47 million metric tonnes of heavy fuel oil and emitted about 2.4 million metric tonnes of SO2. Comparison with port and regional studies shows good agreement in total estimates and better spatial precision than current top-down methods. In quantifying limitations of top-down approaches that assume existing proxies for ship traffic density are spatially representative across larger domains, we find that International Comprehensive Ocean-Atmosphere Data Set (ICOADS) proxy data are spatially biased, especially at small scales. Emissions estimated by STEEM for ships within 200 nautical miles of the coastal areas of the United States are about 5 times the emissions estimated in previous studies using cargo as a proxy.

Simple Analytical Expressions for the Height, Location, and Steepness of a Ship Bow Wave

Dimensional analysis and other fundamental theoretical considerations (thin-ship limit, shallow-draft and deep-draft limits) are used, with bow-wave measurements for six wedge-shaped hull forms, to obtain simple analytical expressions that explicitly define the height, location, and steepness of the bow wave generated by a ship in terms of the ship speed, draft, and waterline entrance angle. These simple analytical expressions are in excellent agreement with the available experimental measurements for six wedge-shaped hull forms. Good agreement is also obtained for other ship-bow forms, especially if a simple procedure—illustrated for the Wigley hull and the Series 60 model—is used to define an effective ship draft and an effective waterline entrance angle.

The Managing Of The Navigational Safety OfShips In Port Water Areas

Existing ports are expected to service ships greater than those for which they were designed. The main restriction is the depth of port waters. The under keel clearance of a maneuvering ship determines ship movement safety. In Polish ports, maximal keel clearance is fixed as determined by port law, but it is possible to change the maximum ship draught depending on the present and predicted conditions regarding the water level. This paper presents an assessment of navigational risk as a combination of impact against the ground and the results of ship hull damage. The results of this research can be used to improve ship movement safety in order to optimize the exploitation of ports.

Ship Traffic Modeling Methodology for Ports

Simulation is a very powerful tool for the analysis and planning of seaport operations. A well-designed and calibrated simulation model can provide useful insights about complex port operations that analytical models cannot capture accurately. An important part of any port operations simulator is the module that produces the ship traffic. This paper presents a ship traffic modeling methodology based on statistical analysis of containership traffic and cargo data obtained from a port in the United States. Implementation of the described procedure led to the creation of a simulation algorithm that captured ship traffic characteristics well. Functional relationships are also developed between ship length and ship draft and between ship length and cargo capacity. The relationship between the average number of handled containers and the number of cranes used is described. The information and conclusions provided here are intended to give guidance on achieving time efficiency and accuracy in the modeling of ship traffic and calibration of container port simulation models.

Prediction Of The Ship Wake On A Restricted Waterway

The paper refers to the prediction of ship wake in the propeller plane, of an inland navigation vessel. Different theoretical models were applied to determine the coefficient of ship frictional resistance and spatial distribution of flow velocity around the hull. The effects of ship draught and velocity of stream in the river were considered. Frictional resistance coefficient was evaluated for a number of generalised hull shapes using the FLUENT computer software. The results of computations were compared with the available experimental data.

向い波中箱型台船の曳航抵抗と索張力 : 曳行台車による模型実験

Concerning the towing problems with tug-towed ships system, some factors such as the towline length, the towing speed, waves, the location of towing point should be considered. However, these important factors have been left to the knowledge and the experience of towing operators up to the present time. In order to ensure the safety of tow ships, it is desirable to develop the optimum method of towing system from the viewpoint of tow operators. In this paper, we carried out water tank experiments using a barge model ship in calm water and regular waves respectively. The characteristics of towing resistance coefficient were examined according to four elements, namely the towline length, the towing speed, the waves length/ship length ratio (λ/L), and the ship draft. In the experiment, it was observed the appearance of impulsive towline tension due to surging motion and encounter waves.

流出油拡散防止膜の滞油限界と膜諸元に関する一考察

The authors proposed "Oil-curtain" which prevents spilt oil from diffusion by enclosing a hull with thin curtains just after a tanker accident. In the design of the device, external conditions which influence the performance to contain oil should be given. In this paper, the conditions are investigated and some model experiments are carried out to examine the performance under the conditions. In addition, the fundamental guidance required in fixing the principal factors of the device, depth of the curtain and weight of the sinker, is shown. The obtained results are summarized as follows. (1) A percentage of oil spillage against carrying capacity depends on dead weight tonnage of a ship. Therefore, the capacity to contain oil should be estimated at every tonnage. (2) 4 knots is the maximum flowing velocity to contain oil by the curtain with the sinker of 1kg/m^2 against Acw, where, Acw=an area of the curtain in water. (3) In beam sea, the contained oil is thrown up onto the deck by waves of less than 3m height. (4) The shape of curtain containing oil can be replaced to the simple model which is calculated with two dimensional analysis. The calculated Ym is larger than experimental results, where Ym=transverse distance between ship's side and the curtain expanded by hydrostatic pressure of oil. (5) To contain oil effectively in flow or beam sea, the additional depth of curtain under the oil layer is from 0.2Ym to 1.5d, where d=ship draft.

A NEW NUCLEAR DENSITY GAUGE TO MEASURE DIRECTLY HIGH TURBIDITIES IN MUDDY AREAS

A better knowledge of the characteristics of muddy areas, in access fairways and port basins, and of the behaviour of ships during their crossing, presents the double interest of enhancing the navigation possibilities, through a more precise adjustment of the ship draught to the status of the bottoms, and permiting a more rational organization of the maintenance dredging campaigns. Considerable savings will be obtained through the development of such knowledges for harbours management. These improvements imply the use of measuring equipments which must be handy, sturdy, reliable and which give accurate measurements. The JTD3 gauge presented by the Radioisotopes Applications Service of the French Atomic Energy Commission is an important step in the development of such measuring equipments. It is now in running order, and commercially available, after thorough test campaigns, undertaken during many months in different french harbours. New developments are already engaged, namely through the design of a turbidity gauge able to make dynamic measurements.

Hydrodynamic energy transfer in shallow water ship impacts

Experiments are described in which a model ship was pushed sideways onto a single, centrally placed, elastic fender to represent a 100,000 D.W.T. oil tanker berthing on a fender of average stiffness. Underkeel clearance, the position of a solid quay wall, and the history of ship motion before impact are shown to be important factors in determining the amount of energy transferred from the water to the fender in addition to the transfer of the kinetic energy of the ship. In conditions giving an underkeel clearance of less than 10% of the ship's draft there is higher energy transfer than previously found by experimenters and it is suggested that energy transfer coefficients in the range 10–20 should be assumed for sideways ship impacts in very shallow water pending the availability of further data.

STUDY OF SHIP'S TRACK AND MOTIONS AT PORT TARANAKI

This paper describes a study carried out at Port Taranaki, New Plymouth, New Zealand to determine ship's track and motions at the port entrance. The results of the study being used to establish the extent (plan area) and optimum depth of proposed capital dredging works. The time lapse photographic technique, incorporating reference levels and bearings in each frame, used to record vessels entering and leaving the port is described, Maximum increases in ship's draft due to sea conditions are given.

The Surveying Requirements for Deep-Draught Routes

Less than a third of the world’s continental shelves has been surveyed by echo sounder, the rest, if surveyed at all, has been covered only by hand-lead and line. Large rocks and wrecks undoubtedly lie undetected between individual casts of the lead and even between quite modern echo sounding profiles. The draught of merchant ships has doubled since the 1960s. Minimal underkeel clearances are now accepted and many new routes are being used across the continental shelves between offshore energy exploitation platforms and new shore terminals. Examples are given of typical shelf surveys and of various ways of meeting modern requirements, including the use of multiple echo sounders, sidescan sonars and sector scanning sonars. Reference is made to the effects on charting of the increasing amount of data available on individual wrecks and seabed obstructions as well as the use of traffic separation schemes. Attention is drawn to the need to monitor the depth in unstable seabed areas, the effect of negative surges and the need for source-data diagrams on charts.

Comparison of the effect of finite draught of a flat-bottomed ship and a full-bodied ship

Numerical computations are carried out for different length: draught ratios for the two kinds of ships-flat-bottomed and full-bodied. The graphs show that for the flat-bottomed ship the wave resistance is greater as expected. One numerical table and the graphs also reveal some interesting features of the differences in wave resistance co-efficient for the two types of ships. These features are discussed.