The Maneuvering And Rudder Sizing Engineering Essay

Published:

This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.

Containerships provide an effective way of transporting manufactured goods, parts, and components. The containership Icarus is designed for reduced process time of loading- unloading, and meets the customer's need of having a design that is energy efficient and environmentally friendly. Containerships play a crucial role in the modern shipping. The economic prosperity and development as a global phenomenon increased the demand for product transportation and led containerization to a new high level. Although, the effects of current economic slowdown cannot be overstated, container shipping will continue to be a sector with 7% to 8% annual growth until 2015 [1] . Given these facts, Aegean Engineering has taken the immense responsibility of developing a hull design for demanding marine operations that is high quality, sustainably efficient, and green.

The design is concerned with the synthesis of a vessel considering the extremely broad and conflicting requirements imposed. Icarus is a containership that operates under a U.S flag and has a carrying capacity of 3200 TEU. It is designed to cover a distance of 5750 nautical miles between the container terminals of Shanghai-China and Los Angeles-USA. China has become the world's workbench for many products and U.S trade power relies heavily upon the developing market of China. Moreover, the client's requirements specified an operational speed of 20 knots and the capability of transporting refrigerated products with 300 containers of adjustable temperature.

Icarus is not bound by any requirements for containers with hazardous contents. The design was implemented with a double hull to protect the environment, crew and cargo in case of damage. Icarus features a bulbous bow, useful for increasing the fuel efficiency, reducing drag force and supporting the longitudinal stability. Container terminals, as modern port constructions, utilize special cranes for moving the cargo on and off the ships; thus the installation of a crane system on Icarus is not an operational requirement. Moreover, the dynamic and hydrostatic stability has to be maintained at a 50 percent load condition.

The pre-design includes all the conceptual and contractual activities. The modeling and optimization techniques for developing a multidisciplinary approach to the vessel design are analyzed through all the process. The problem involves all the contractual variables. Length, beam, draft and block coefficient were extensively used to create an efficient hull that can meet all the pre-design requirements such as the trim, metacentric height and weight-displacement relationship. Ships with similar carrying capacity were reviewed for the basis of an initial design. Container capacity, weight, stability, powering, and cost were analyzed and compared for ten different initial designs, until the owners requirements were met at the lowest cost.

The final design incorporates all the owner's requirements while meeting regulations outlined by all the major regulating committees such as the American Bureau of Shipping (ABS), Code of Federal Regulations (CFR), the International Maritime Organization (IMO), the Safety of Life at Sea (SOLAS), and the United States Coast Guard (USCG). The necessity of passing the prescribed regulations is a crucial factor for the survivability of the vessel and crew. Moreover, the design benefits the ship-owner economically by servicing financially developed territories of high manufacturing interest.

An early estimate of principal dimensions was made according to regression analysis results obtained from existing ships. Several iterations developed into the dimensions that gave Icarus her final arrangement. Principal dimensions along with the principal characteristics that are of major concern for personnel involved with the process of design, construction, and operation of Icarus are displayed in Table 1.

Table 1-Summary of Principal Characteristics

Principal Characteristics

Design Value

LOA

242.6 m

LWL

233 m

B

39 m

D

19 m

T

10.25 m

Cb

0.698

Capacity

3,200 TEU

Speed

20 knots

Displacement

66,971.5 ton

Endurance

11,500 nm

Installed Power

21,910 kW

Crew Members

21

Cost

$165 million

Icarus is designed with hatch coverless cargo holds and the presence of container rails is important to ensure stable positioning. The vessel accommodates 3,200 containers either in the hull of the ship, or on the main deck. A total of seven layers of containers fit within the larger cargo holds enclosed and up to five layers of containers above deck. A 1.5 meter spacing was created between every two containers to allow room for container inspection and crew tasks. The cargo area is separated by transverse bulkheads every 27 meters to support the vertical strength of the construction and retain damage to a limited area. The profile and internal design was performed with recognition of regulatory requirements, and consideration of similar designs. The principal dimensions are indented for improved seakeeping characteristics while providing the required form of the hull to fit the cargo properly.

The accommodation deck is designed under the CFR requirements and includes living spaces for a crew of 21. The height of the navigation bridge is qualified to have a visibility range exceeding the 500 meters requirement. Moreover, Icarus will carry two lifeboats at the port and starboard sides. Several other life saving appliances will be located along its compartments, and superstructures, promoting maritime safety standards.

The engine room is located beneath the accommodation deck to offer rapid and convenient access to the machinery spaces. The adjacent steering gear room offers adequate space for the storage needs and provides a base where more containers can be loaded. The required engine power as indicated in Table 1yields affordability, low consumption and small diesel and lubricant oil tanks. The overall engine-propeller system is described by high efficiency and the ability to give thrust even in very rough seas.

Icarus potentially offers many advantages to shipping companies. It successfully meets all requested specifications for speed, payload, and radius of operation. Navigation between busy ports will be more affordable and brings higher profits. The vessel's overall efficiency is respectable and provides a safe and environmentally friendly environment. The merits of such a design are direct and make Icarus, the right choice for the modern global shipping services. The low construction price clarifies the success of this development.

2.0 TECHNICAL SUMMARY

2.1 Introduction

The evolution of shipbuilding has caused a significant increase in the volume, value and relative importance in design activities. Design activities have an important impact on many other costs like materials, subcontracting, production etc. as well as on delivery time. The report outlines the process of the preliminary design and presents the results obtained considering an efficient vessel from the perspectives of hydrostatics, cargo placement, weights and powering. Moreover, comments will be made on the extent to which how a minor alteration in the variables affects the predicted design.

2.2 Requirements

The owner's requirements phase determines the client/owners desires and needs in a vessel. For larger vessels, the requirements may include market evaluations or traffic studies. For fleet expansions, this may include elements of interoperability or similarity with existing vessels. Owner requirements can change over the course of a project as feasibility of design aspects become apparent, supporting documents (such as environmental studies) are developed, or as the owners own requirements change over time. Icarus initial requirements are presented in Table 2.

Table 2-Summary of Initial Requirements

Requirements

Design Values

Speed

20 knots

Cargo

3,200 TEU

Refrigerated Cargo

300 TEU

Hazardous Cargo

Nil

Starting Port

Los Angeles/USA

Ending Port

Shanghai/China

Flag

United States

Operational Range

11,500 nautical miles

Moreover, the vessel as indicated in Figure 1 is required to operate between the container terminals of Shanghai-China and Los Angeles-USA, which corresponds to a total distance of 11,500 nautical miles for a roundtrip through the Pacific Ocean. Icarus will be registered under a US flag and will accord with its regulations and habitability requirements.

SEARATES.png

Figure 1-Operational Range showing the Route of the Required Trip

2.3 Principal Characteristics

Icarus' design successfully carries out the endurance distance of 11,500 at a maximum of 23 days of travel with an operational speed of 20 knots. Ideally, the journey between Los Angeles and Shanghai can be accomplished in less time, but considering the length of the route and the variable sea conditions a safety margin of additional 52 miles was considered mandatory. The requested cargo is transferred with a relative ease and the principal dimensions provide the vessel with the ability to enter and exit safely from both ports. Compared to standard designs and suggested vessel dimension ratios, Icarus follows the trend-line created in prior years, with a much lower construction and maintenance cost. Table 3 summarizes the principal characteristics that make Icarus a feasible solution for the needs of the trip.

Table 3-Summary of Principal Characteristics

Principal Characteristics

Design Value

LOA

242.6 m

LWL

233 m

B

39 m

D

19 m

T

10.25 m

Cb

0.698

Capacity

3,200 TEU

Speed

20 knots

Displacement

66,971.5 ton

Endurance

11,500 nm

Installed Power

21,910 kW

Crew Members

21

Cost

$165 million

2.4 Hull Design

Maxsurf software was used for the parametric transformation of the parent hull. The dimensional variables were iterated multiple times to achieve a ratio of less than one between weights and displacement. Icarus features a bulbous bow that reduces drag and increases the cruising efficiency. The transom is located enough higher from the base line in order to ensure the safety at the aft part of the vessel. The drawings line plan presented in Figure 2 consists of the profile elevation, the plan view side and the body plan of the vessel.

2.5 General Arrangement

2.6 Propulsion

An estimation of the engine specifications was made through the use of the preliminary powering program. Initially, according to Silverleaf & Dawson's prediction method, a marine engine with 23001.9 kW brake power was required. The use of propeller optimization program (POP) in conjunction with power prediction program (POP) determined the final required installed power to propel the ship. The results obtained from PPP yielded an engine of 23.150 kW that agrees with the initial estimation. After a thorough product investigation, a 6-cylinder Wärtsilä RT-flex68-D was concluded to fit best the vessel. Moreover, the aforementioned engine type posed the sizing of the fuel oil and lubricating oil tanks that are required onboard the ship to meet the trip needs. The operational characteristics of the marine engine are listed in Table 4.

Table 4-Summary of Engine Specifications

Specification

Design Value

Engine Model

Wärtsilä RT-flex68-D

Number of Cylinders

6

Rated Output

23.150 kW

RPM

102

Fuel Consumption

170 g/kWh

Lubricant Oil Consumption

0.6 g/cylinder

Weight

439 ton

Length

10.3 m

2.7 Propeller Selection

Evaluating the output of power prediction program as input to propeller optimization program, a propeller of 7.3 m diameter, and an open water efficiency of 0.605 was selected to drive Icarus. Moreover, Propellers with odd number of blades were analyzed to minimize the vibration caused by wake interference. The installed propeller characteristics are displayed in detail in Table 5.

Table 5-Summary of Propeller Specifications

Specification

Design Value

Diameter

7.3 m

Pitch/Diameter Ratio

0.6607

Expanded Area Ratio (Ae/Ao)

0.6356

RPM

102

Thrust Coefficient (KT)

0.1266

Torque Coefficient (KQ)

0.01416

Open Water Efficiency (η0)

0.605

Cavitation Number (σ)

0.2638

2.8 Maneuvering and Rudder Sizing

The evaluation of maneuvering features was performed by using the Maneuvering Prediction program, provided by the University of Michigan. For an operating speed of 20 knots, the analysis provided the certainty that Icarus is able to steer on course and turn when necessary. The vessel's turnability is a factor of Clarke's turning index, linear dynamic stability criterion, advance, and tactical diameter. The aforementioned factors met the requirements posed by the International Maritime Organization for full and 50% load conditions. Moreover, the rudder area size of 47.117 m2 was determined based on the maneuvering features of the vessel. The maneuvering characteristics are displayed in Table 5.

Table 5-Summary of Maneuvering Analysis

Icarus

Required

Clarke's Turning Index

0.4808

>0.4

Linear Dynamic Stability Criterion

3*107

>0

Advance

663.6 m

<855

Tactical Diameter

801.3 m

<950

Electrical Generation

Four electric generating sources were selected to cover Icarus' needs for electric power. The high demand for electricity in order to refrigerate 300 TEU brought concerns considering the increased fuel consumption. The selected generator models operate with fuel oil, like the main engine and can supply power equivalent to 13,440 kW. Similar vessels were examined to estimate the required power supply and provide sufficient knowledge to conclude to the best power supply arrangement. Ships operate in harsh environments, thus a generator that could provide extra power is considered mandatory. A Wärtsilä Auxpac 2100W8L26 operating at 60 Hz was determined to be used in case of emergencies. A summary of power generation capacities is presented in Table 5.

Table 5-Summary of Power Generation Capacities

Specification

Design Value

Model

Wärtsilä Genset 32

Individual Rating

3,360 kW

Number Installed

4

Total Ship Service Power Available

13,400 kW

Emergency Power

1,110 kW

2.10 Weights Analysis and Loading Conditions

The vessel's weight analysis was performed for a full load departure and arrival. To ensure the dynamic stability, an analysis for 50% load at departure and arrival took also place. The requirements posed from the U.S.C.G and ABS were met successfully for all loading conditions. Trim, metacentric height and the submergence of the propeller were found to be adequate for safe and efficient trip. The computed values for each loading condition are presented in Table 6.

Table 6-Stability at Various Loading Conditions

GMT (m)

GM1 (m)

TF (m)

TA (m)

Trim (cm) +by the stern

KG (m)

Propeller Submerged %

Full Load Departure

1.06

352.13

10.69

10.68

0

17.86

100

Full Load Arrival

0.93

351.67

10.49

10.75

0.27

17.99

100

50% Load Departure

7.71

488.01

6.18

6.87

0.69

15.38

81.64

50% Load Arrival

7.75

480.59

6.34

6.94

0.6

15.08

80.51

2.11 Midship Section Analysis

Icarus' maximum still water bending moment was analyzed with HydroMax's longitudinal strength program. The vessel complied with the regulations described by the American Bureau of Shipping. The ship structure exceeded the minimum requirements for the midship section modulus and moment of inertia. A comparison of the midship characteristics between the required and calculated values is listed in Table 5.

Table 5-Comparison of Required and Calculated Values of Midship Section

Icarus

ABS Requirements

Deck Section Modulus

161.14 cm2m

160.066 cm2m

Bottom Section Modulus

175.241 cm2m

160.066 cm2m

Total Moment of Inertia

1,334,764 cm2m2

913.824 cm2m2

2.12 Seakeeping Prediction

The seakeeping performance of Icarus was calculated from the seakeeping prediction program (SPP). Icarus' performance was successful for sea state 3. The rough seas observed in Pacific Ocean make certain a further investigation of seakeeping. Motions for heave, pitch and roll are estimated and presented in Table 6 below.

Table 6-Seakeeping Characteristics in Sea State 3

Maximum

Minimum

Heading

Magnitude

Heading

Magnitude

Roll

50°

2.3°

0°~180°

0°

Pitch

50°

0.1°

130°

0.6°

Heave

50°

0.6 m

0°

0.15 m

2.13 Floodable Length Analysis

A floodable length analysis was performed in order to place the bulkheads in the hull of Icarus. The assessment was carried out in HydroMax for permeabilities between 0.7 and 0.95. The location of the eight watertight bulkheads allows the ship to pass even the worst case scenario of two compartments flooded with a 95% sea water volume. The results for the floodable length analysis are presented in Figure 5 below.

2.14 Damage Stability

Icarus was subjected to a damage stability test. The damage scenario tested the case of two flooded compartments along the hull. Icarus met the IMO Dry Cargo requirements, keeping itself integral to longitudinal strength and stability. Several counter flooding options to improve trim conditions were also investigated and successfully passed regulations IMO SOLAS, II-1/8 and the requirements of US Coast Guard, Part 170 of Subchapters: Stability Requirements for All Inspected Vessels.

2.15 Cost

Icarus' initial design cost was $175 million based on the principal dimensions obtained through regression analysis. The cost reduced by 10.5 $ million during the overall design process. The vessel's cost has been a key factor in determining the hull modifications and necessary equipment. The factors that could potentially increase the cost concerned mainly the dimensions and the engine selection. Other affecting economic factors such as the propeller pitch and the addition of a bow thrust contributed a little to the final cost. The final cost of Icarus is calculated at around $166.5 million. Icarus constitutes an economically beneficial solution compared to same size containerships.

2.16 Conclusion

Writing Services

Essay Writing
Service

Find out how the very best essay writing service can help you accomplish more and achieve higher marks today.

Assignment Writing Service

From complicated assignments to tricky tasks, our experts can tackle virtually any question thrown at them.

Dissertation Writing Service

A dissertation (also known as a thesis or research project) is probably the most important piece of work for any student! From full dissertations to individual chapters, we’re on hand to support you.

Coursework Writing Service

Our expert qualified writers can help you get your coursework right first time, every time.

Dissertation Proposal Service

The first step to completing a dissertation is to create a proposal that talks about what you wish to do. Our experts can design suitable methodologies - perfect to help you get started with a dissertation.

Report Writing
Service

Reports for any audience. Perfectly structured, professionally written, and tailored to suit your exact requirements.

Essay Skeleton Answer Service

If you’re just looking for some help to get started on an essay, our outline service provides you with a perfect essay plan.

Marking & Proofreading Service

Not sure if your work is hitting the mark? Struggling to get feedback from your lecturer? Our premium marking service was created just for you - get the feedback you deserve now.

Exam Revision
Service

Exams can be one of the most stressful experiences you’ll ever have! Revision is key, and we’re here to help. With custom created revision notes and exam answers, you’ll never feel underprepared again.