PORT and Harbor Engineering 3

8/14/2019 PORT and Harbor Engineering 3

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PORT and Harbor

Engineering

Radianta Triatmadja

Lecture note 2


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Waterway Design

Depth of Waterway


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Waterway Design

The depth of waterway depends on the

tonnage of the ship and the water.

Following Archimedes law, the amount of

water displaced by the ship equals the

weight of the ship. Therefore the more is

the tonnage, the deeper is the ships draft.

Ships draft also depends on the cross

section of the ship.


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Draft

draft draft50 000 ton 50 000 ton

Ships of the same total weight may have different drafts.


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Draft

Box Coefficient


= Cb

Cb =0.8Cb =0.6


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Draft

Box Coefficient


= Cb

Cb =0.5Cb =0.67


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Tonnage

Displacement tonnage : The weight of

water displaced, the physical weight of the

ship

Loaded Displacement : the weight of the

ships + loading

Light displacement : the weight of the

ships only


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Tonnage

Dead weight ton : The difference between

loaded displacement and light

displacement, or the weight of loading

(please do not confuse this tonnage with

the weight of the ships)

The weight of fresh water, tools, and fuel

are considered as loading


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Tonnage

Gross Registered ton (use for Passenger

ships)

Volume of ships space in cubic feet divided

by 100

1 GRT ~ 2.83 m3


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Typical ships full load draft of Bulk carrier

Weight (1000 tons) Draft (m)20.99 9.5764

22.934 10.5138

23.67 10.2352

23.96 10.2352

24.911 9.9566

26.055 8.056427.48 10.2606

34.586 10.5138

35.316 10.9694

44.477 11.7552

46.73 12.0084

48.976 11.527450.055 11.552

50.692 11.552

52.458 12.0592

56.672 12.2108

60.639 12.895

170.418 18.9242

y = 2.1393Ln(x) + 3.6789

R2 = 0.9906

0

2

4

6

8

10

12

14

0 10 20 30 40 50 60

Weight (1000 tons) Draft (m)

1 4.2

2 4.95 6.8

10 8.5

15 9.3

20 10

30 10.9

40 11.7

50 12.4


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y = 3.965Ln(x) - 3.1657

R2 = 0.8525

0

24

6

8

10

12

14

16

18

20

0 50 100 150 200

Typical tonnage and full load draft of bulk

carriers (ore, coal, cement etc)

Draft(loaded)

Dead weight (1000 tons)


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Passenger Ships

y = 1.9623Ln(x) + 2.7951

R2 = 0.9546

y = 1.6041Ln(x) + 2.6762

R2 = 0.9807

0

2

4

6

8

10

12

0 5 10 15 20 25 30 35

Depth required / draft = 1.14

Basin depth for unknown full draft

X 1000 ton


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Container Ships

y = 0.08x + 9.1

R2 = 0.9877

y = 0.1x + 10

R2 = 1

0

2

4

6

8

10

12

14

16

0 10 20 30 40 50 60

Weight (x1000) draft depth

20 10.6 12 1.132075

30 11.6 13 1.12069

40 12.4 14 1.129032

50 13 15 1.153846

Depth/draft= 1.13

Basin depth for unknown full draft


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Depth of waterway

The depth of waterway should be deeper than

the basin. Provisions should be made for

possible pitching, heaving and squat

Squat Z

2

2

2

1

4.2

F

F

LZpp


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Additional depth due to

Vertical movement due to wave (heaving)

Vertical movement due to Squat

Vertical movement due to pitching


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Required Water depth

Expected vertical movement

Net underkeel clearance

dredging tolerance

Draft (ship size)

Expected sediment accumulation between two dredging campaigns

Tobedredg

ed

Sounding tolerance

Keel = bottom

Gross underkeelclearance


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How to design waterway depth?

Define Maximum Ships weight and type

Calculate/predict Ships draft

Define minimum water level

Calculate depth Required (1.15 timesShips draft) (nominal depth)

Calculate expected sedimentaccumulation during two consecutivedredging works

Calculate total depth required to dredge


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What is minimum water level ?

Sea level is fluctuating due to moon and

sun attraction forces and centrifugal

forces of the earth during its revolution

about its common axis with the moon

This fluctuation is called tides

Maximum fluctuation occur during spring

tide, while minimum fluctuation occur

during neap tide.


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Tidal constants

Tidal waves are periodic due to the

driving forces. Yet so many conditions

affect the periodicity of the tidal waves. A

complete period of tide wave isapproximately 19 years. In order to design

a harbor one need to know tidal constants

in the design area. These tidal constantsgovern the major water level fluctuations.


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40.Air Pelayaran Sebelah Barat Surabaya

(Karang Jamuang)

0

4

8

12

16

20

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0 100 200 300 400 500 600 700 800 900 1000 1100 1200

Time

Elevasi

An Example of Water level

Fluctuation

hours

dm

NeapSpring


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Discussion

A Harbor designed is given to be discussed. Topics to bediscussed are :

2. What is the maximum size of ships that can be served

3. The width of the waterway

4. During spring tide even larger ships can enter the harbor. What

is the maximum size of the ships during spring tide? Discuss thepossibility of allowing such ships to berth in the harbor

5. If the speed of your ships are limited to 10 knots along thewaterway, what is the maximum squat ?

6. Do you have any comment other than the topics discussed ?

7. Within the next 10 years the harbor will be upgraded to serveships of maximum draft 4 meters. What works are needed?

PORT and Harbor Engineering 3

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