calculation of displacement, lwt and dwt

Document no : 01 - 42 08 071 -ES

Attachment

Number of pages

Electrical Systems and Engine Room

Displacement, LWT and DWT

rev. date Document Title Prepared by Reviwed by Approved by

Miftahuddin nur Ir. Dwi Priyanta

,MSE

Ir. Hari

Prastowo, Msc.

Project : DESIGN IV

Doc. No : 01 - 42 08 071 - ES

Rev. No :

page. No : II

Table of contents

1. Introduction…...………………………………………………………………………………………………….. 1

2. Objective……………...……………………………………………………………………………………………. 1

3. Reference………...………………………………………………………………………………………………… 1

4. Abbreviation……………...………………………………………………………………………………………. 1

5. Description of calculation…………….....……………………………………………………………….. 2

6. Summary ............................…………………………………………………………………………….. 7

List of attachments

attachments 1 Detail Equipment list code………………………………………………………….. 4

Displacement, LWT and DWT

Project : DESIGN IV

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Rev. No :

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1. Introduction

1.1. Displasement

1.2. Light Weight Tonnage

1.Weight of ship's structural

2.Weight of outfitting

3.Weight of Machinery

4.Recidual Weight

1.3. Dead Weight Tonnage

2. Objective

3. Reference

Practical Ship Design, Chapter 4 Weight-Based Designs, D.G.M. Watson

4. Abbreviation

Lpp = Length of between perpendicular

Lwl = Length of waterline

B = Breadth of ship

H = Height of ship

T = Draught of ship

Vs = Ships velocity

Cb = Block coefficient

ρsea water = Sea water density

K = Wet steel weight's constant

SFOC = Specific Fuel Oil Consumption

Displasement, LWT dan DWT

Displasemen volume is the total volume of water displaced by the weight of an

object. There are two factors that affect the displacement of the ship, the

weight of the ship components that can be transformed (DWT) and the weight

of the ship components that can not be changed (LWT).

Is the weight that come from the value of weight displacement minus the light

weight tonnages. That consist of cargo's weight, fuel oil, fresh water, ballast

water, provision and ship's crew weight

The objective of this document is to determine the estimation of displacement, light

weight tonnage, and dead weight tonnage in order to find the relation between

Based on the book "Practical ship design chapter 4" LWT ship explained that

consists of several components:

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W res = Reserve weight

▼ = Displacement volume

∆ = Ships displacement

Wst = Wet steel weight

E = Steel weights parameter

l1 = Length of forecastle deck

l2 = Length of poop deck

h1 = Height of forecastle deck

h2 = Height of poop deck

Woa = Weight of outfit and accomdation

Wm = Machineriy weight

= Main engines weight

= Maximum continous rating (kW)

= Engine RPM

Wr = Auxiliary engines weight

Wres = Reserve weight

5. Description of calculation

5.1 Displacement Calculation

a. Displacement Volume

▼= Lwl x B x T x Cb

where : ▼ = Displacement volume

Lwl = Ships length on the water line

B = Ship width in the middle of ship

T = Draft on fully cargo

Cb = Block coefficients

b. Weight Displacement

∆ = ▼x ρ sea water

where : ∆ = ships displacement

▼ = ships displacement volume

ρ sea water = the density of sea water

5.2 Light Weight Tonnage

a. Weight of ship's structural

MCR

According to the book "Practical Ship Design chapter 4/4.2.4"by DGM

Watson, to calculate the weight of the structure of the ship can use the

formula :


RPM

Wd

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where : K = Coefisien, depend on ship type

E = Equipment Numerical

E = L ( B +T ) + 0.85 L ( D -T ) + 0.85 ( l1 h1 ) + 0.75 ( l2 h2 )

Where :

L = legth between perpendicular

B = breadth

T = draft

D = depth

l1 = length of full width erection

h1 = height of full width erection

l2 = length of houses

h2 = height of houses

b. Weight Outfit and accommodation (Woa)

c. Weight of Machinery

Divided into two components: propulsion machinery and remainder.

c.1.

Wd = 12 (MCR/RPM)0,84

c.2

Wr = K x (MCR)^0.70

Wst = K x E1,36

Based on the book "Principal Ship Design"by DGM Watson page 108

Chapter 4.5.4, Main Engine weight can be estimated with the following

formula :


Chapter 4.5.5, weight of remainder can be estimated with the following

formula :

Calculation above,is for ship having Cb = 0.70 to 0.8 H. But, this ship have a

Cb = 0,615, so that needed to do a correction .

For heavy outfit and accommodation according to Practical Ship Design,

page 99 chapter 4.4, it can be seen the value of Wo/L xB.For container

ships withLpp 112 m = 0,3

According the value of the number of equipment (E) Lyold appropriate as

written in the book "Practical Ship Design"by DGM Watson, referring to the

1877 RINA (Lecure Ship Design and Ship Theory, Poels Herald p. 69A) with

the following formula:


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So the result of Machinery Weight is Wd+Wr,

Wm = Wd+Wr

d. Recidual Weight

Wres = 2% (Wst + Woa + Wd + Wr + Wmt)

LWT = Wst + Woa + Wd + Wr + Wmt + Wres

5.3 Dead Weight Tonnage

DWT = ∆ - LWT

5.4 Payload

Payload = DWT - Wtotal

where,

DWT = Dead Weight Tonnage

Wtotal =Weight of fuel oil, diesel oil, lubricating oil, crews and

provision, fresh water

i. HFO (Heavy Fuel Oil)

a. HFO's weight

The formula, as follows :

WHFO = SFOC x BHP x time to voyage x constants addition of fuel

Where,

WHFO = weight of heavy fuel oil

SFOC = specific fuel oil consumption (project guide)

BHP = break horse power of main engine (project guide)

constants addition of fuel = 1.3 - 1.5

Payload is the total weight of cargo that can be transported by ship to the

income (profit) of a ship. Here are steps in determining the payload.

According to Practical Ship Design on page 114, for the calculation of

reserves it is necessary to add weight. Weight by 2-3% due to avoid

mistakes in planning and things that might not been included in previous

calculations. So the formula of recidual weight is :

Now we know the value - the value of weight above in accordance with the

previous explanation, then we can calculate the value of LWT by summing the

weight calculation remains the ship:

According to the book "Ship Knowledge A Modern Encyclopedia" page 28,

Deadweight is the weight of that load cargo ship laden water up to a maximum

allowable. This can be formulated with the formula:


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b. HFO's tank volume


VHFO = ((100%+3%)*WHFO)/ ρHFO

Where,

VHFO = HFO's tanks volume

WHFO = weight of heavy fuel oil

Alocation of expansion = 3%

ρHFO = 0.991ton/m3

ii. DO (Diesel Oil)

a. DO's weight

estimation of diesel oil's weight is 10%-20% of hfo weight

for the result :

WDO = 20% x WHFO

b. DO's tanks volume


VDO = ((100%+3%)*WDO)/ ρDO

Where,

VDO = DO's tanks volume

WDO = weight of heavy fuel oil

Alocation of expansion = 3%

ρDO = 0.85 ton/m3

iii. LO (Lubricating Oil)

a. LO's weight


WLO = SLOC x BHP x time to voyage x constant addition of fuel

where,

SLOC = Specific Lubricating Oil Consumption = 0.95 g/BHPh

Constants of fuel = 1.3 - 1.5, take 1.4

We should consider about the increasing temperature inside the

tanks of HFO, so we add some alocation of expansion margins

approximately 2% - 3%.

We should consider about the increasing temperature inside the tanks

of DO, so we add some alocation of expansion margins approximately

2% - 3%.


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b. LO's tanks volume


= WLO / ρLO

where,

ρLO = 0.9 ton/m3

iv. Fresh Water

a. Consumption for crew

fresh water needs estimation = kg/persons/day

b. Bath and laundry needs


c. Cooking needs


d. Machinery needs

1. main engine

fresh water needs estimation = 7 gr/kWh

2. auxiliary engine

fresh water estimation = 0.2 from main engine's fresh water

Total fresh water machinery = fw ME + fw AE

Total Weight of Fresh Water

= consumption for crew + bath and laundy + cooking + machinery

Total Volume of Fresh Water

= divide the total weight of fresh water by its density.

v. Crew and Provision

a. crew's weight

total crews = 20 persons

average weight of crews = 70 kg

b. provision's weight

average provisions needs = 5 kg/person/day

Weight Total of Ship Supplies

W total = WHFO+WDO+WLO+Wfreshwater+Wcrews+Wprov

PAYLOAD = DWT - W supplies total

VLO

We should consider the increasing temperature inside the tanks of

LO,so we add some alocation of expansion margins approximately 2% -

3%.


20

200

4

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6. Summary

NO

1

2

3

4

5

Weight Displacement ∆ 9637,17 ton

CALCULATION SYMBOL RESULT

Displacement Volume ▼ 9402,12 m3

Payload 5538,85 ton

Light Weight Tonnage LWT 3953,68 ton

Dead Weight Tonnage DWT 5683,49 ton


Attachment 1Detail Calculation of Displasement, LWT

dan DWT

Project : DESIGN IV

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page. No : 08

1. Calculation Details

Principal Dimension

Container Ship

Lpp = meter h deck = meter

Lwl = meter Power Engine = kW

B = meter = HP

H = meter Sailing distance = n mile

T = meter Sailing time = Hours

Cb =

Vs = knots

= m/s

> Calculation of Ship's Displacement

Volume Displacement

▼ = Lwl x B x T x Cb

= m³

Weight Displacement

ρ = ton/m³

∆ = ∇ x ρ

= ton

Determination of the number of crew

Payload

Payload = DWT - WProvision

16,50

8,49

In determining the number of the crew should be as efficient as possible, as this

affects the size of the room and the limited amount of supplies of food and fresh

water. Factors that influence the type of ship, large ship, the number of jobs

served by the crew, sailing routes, sisitem existing automation on ships, and

regulations of the country concerned.In determining the number of crew that is

used is 20 people.

9402

112,00 2,50

120

Estimation of Displasement,

LWT dan DWT

So to be able to know the payload on the vessel which is designed we must

calculate the first (LWT), which brought supplies and Weight Lightweight

3900

5230

1487

The payload is the cargo on board and pay (making money). The formula can be

used to determine the payload is :

Because the ships operating at sea, then the value of rho(density) was used sea

water rho(density) :

1,025

9637,2

117,60

20,00

8,30

6,50

0,62

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> Light weight (LWT)

~ Weight of ship's structural

where : K = Coefisien, depend on ship type

E = Equipment Numerical

L = Lpp

= m

H = m

Lfore = m (the length of forecastle)

Hfore = m (the height forecastle)

L MAIN DECK = m (the length of MAIN DECK )

H MAIN DECK = m (the height of MAIN DECK)

LDECK A = m (the length of DECK A )

H DECK A = m (the height of DECK A)

LDECK B = m (the length of DECK B)

H DECK B= m (the height of DECK B)

L DECK C = m (the length of DECK C)

H DECK C= m (the height of DECK C)

L DECK D = m (the length of DECK D)

H DECK D= m (the height of DECK D)

Lnav = m (the length of navigation)

Hnav = m (the height of navigation)

l1 x h1 = the length and height of full width erections

l2 x h2 = the length and height of houses

l1 x h1 = Lfore x Hfore

= 20 m2

8,0

2,5

7,0

2,5

3,0

According to the book "Practical Ship Design chapter 4/4.2.4"by DGM

Watson, to calculate the weight of the structure of the ship can use the

formula perndekatan as follows:

Wst = K x E1,36

According the value of the number of equipment (E) Lyold appropriate as

written in the book "Practical Ship Design"by DGM Watson, referring to the

1877 RINA (Lecure Ship Design and Ship Theory, Poels Herald p. 69A) with

the following formula:

E = L x (B + T) + 0,85L x (H - T) + 0,85 (l1 x h1) + 0,75 (l2 x h2)

112

8,3

8,0

2,5

8,0

2,5

8,0

2,5


LWT dan DWT

7,85

2,5

29,5

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l2 x h2 = (LDECK A x HDECK A)+(LDECK B x HDECK B)+(LDECK C x HDECK C)+

(LDECK D x HDECK D)+ (Lnav x hnav)+(L MAIN DECK x H MAIN DECK)

= m2

E = L x (B + T) + 0,85L x (H - T) + 0,85 (l1 x h1) + 0,75 (l2 x h2)

=

K = (for container ship)

Wst = k x E1.36

= Ton

correction of Cb = Cb + ( 1 - Cb x (0,8H - T) / 3T

=

Thus obtained the weight of steel :

Wst = Wst x [1 + 0,05 (Cb0,8H – 0,7)]

= Ton

~ Weight Outfit and accommodation (Woa)

Woa = the value of(Wo / L xB) x Lpp x B

= Ton

~ Propulsion machinery weight

186

Based on the book "Principal Ship Design"by DGM Watson page 108 Chapter

4.5.4, Main Engine weight can be estimated with the following formula :

For heavy outfit and accommodation according to Practical Ship Design,

page 99 chapter 4.4, it can be seen the value of Wo/L xB. For container ships

with Lpp 112 m= 0,3

672,00

0,036

2191

Calculation above,is for ship having Cb = 0.70 to 0.8 H. But, this ship have a

Cb = 0,615, so that needed to do a correction :

6,662

2844,4

3295,5


LWT dan DWT

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Wd = 12 (MCR/RPM)0,84

BHPMCR = kW

= ton rpm=

~ Calculation weight of remainder (Wr)

Wr = K x (MCR)^0.70

= ton

K = (for bulk carriers and general cargo ship)

~ Weight of generator set (Wmt)

Wmt = 0.72(MCR)^0.78 where is :

Wmt = 0.72(MCR)0.78

= ton

~ Calculation of Recidual weight

Wres = 2% (Wst + Woa + Wd + Wr + Wmt)

= ton

~ Calculation of LWT

LWT = Wst + Woa + Wd + Wr + Wmt + Wres

= ton

0,69

225,2

139,6

3900

210


Chapter 4.5.5 , weight of remainder can be estimated with the following

formula :

3953,7

MCR = Maximum

Continous Rating genset

Based on the book "Principal Ship Design"by DGM Watson page 111 Chapter

4.5.6 Generator weight can be estimated with the following formula :

However, because of the power generator to be installed is not known, it is

assumed that the generator will be installed is with the power of 120 kW of

3 sets. So the value can be calculated as follows wmt :

According to Practical Ship Design on page 114, for the calculation of

reserves it is necessary to add weight. Weight by 2-3% due to avoid mistakes

in planning and things that might not been included in previous calculations.


LWT dan DWT

71,00

1,42

Now we know the value - the value of weight above in accordance with the

previous explanation, then we can calculate the value of LWT by summing

the weight calculation remains the ship:

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> Dead weight (DWT)

DWT = ∆ - LWT

= ton

> Payload Calculation

Payload = DWT - Wconsumable

Where :

Wconsumable = WHFO + WMDO + WLO + WFW + WP + WCP

~ Calculation of Heavy Fuel Oil (HFO)

Unknown: g/kWh

P = kW

Constanta addition of fuel oil = 1,3-1,5 taken =

WHFO = SFOC x P x (S/Vs) x constanta addition of fuel oil x 10-6

= ton

Calculation of Volume HFO Tank

VHFO = WHFO/ ρHFO ρHFO = 1 Ton/m3

= m3

VHFO = (1+4%) x WHFO)

= m3

~ Calculation of Marine Diesel Oil (DO)

Weight of Marine Diesel Oil (WMDO)

WMDO = 0.2 x WHFO

= ton

111,99

Diesel oil is usually used as fuel for generators and motor process of flushing

the mains when not operated in the long term. Heavy Diesel Oil which is

carried in shipping approximately 0.1 ~ 0.2 of weight carried HFO, in this

case tken 0,2

21,54

3900

108,66

According to the book "Ship Design and Construction section 5" page 65, in

the calculation of the volume of the fuel tank (HFO) will need to add a

margin of 2% ~ 4% to anticipate expansion of fuel because of increases in

temperature in the tank, so that the volume of HFO tanks required:

Payload is the total weight of cargo that can be transported by ship to the

income (profit) of a ship.Here are the steps in determining the payload weight.

According to the book "Ship Knowledge A Modern Encyclopedia" page 28,

Deadweight is the weight of that load cargo ship laden water up to a maximum

allowable. This can be formulated with the formula:

5683,5


LWT dan DWT

SFOC = 177

1,3

107,7

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Calculation of tank volume MDO

Selected :

type of DO = DM-A

ρ DO (at 15° C) = 1 ton/m3

VMDO = WMDO/ ρ MDO

= m3

V MDO = (1+4%)x VMDO

= m 3

~ Calculation Lubricating Oil (LO)

unknown :

System Oil Approximate kg/cyl.24hours Cylinder Oil

0,8-1,2 g/kWh

taken = g/kWh

WLO = P x SLOC x (S/Vs) x 10-6

= ton

Calculation of Volume LO Tank

Selected :

ρ LO = ton/m3

VLO = WLO / ρLO

= m3

need increase 4% for construction and expansion, so

loss volume = 1,04 x Vlo

= m3

~ Weight of Crew and Provision

Weight provision = Total crew x provision needed per day x Longest trip

Total crew = man

Weight per crew = kg

25,17

According to the book "Ship Design and Construction section 5" page 65, in

the calculation of the volume of the fuel tank (DO) should be added margin

of 2% ~ 4% to anticipate if fuel (DO) terekspansi because of increases in

temperature in the tank, so that the volume of tank DO required:

24,20

0,9

0,52

0,541

20


LWT dan DWT

Based on data from "Project Guide Engine (MAN B & W L35MC) " on the

condition of maximum obtained the following data:

Lubricating Oil Consumption

2

0,8

0,5

70

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Wcrew = ton

weight of total crew = total crew x the average weight of crew

where :

porvision need = 3.5 kg ~ 5 kg /man/day

porvision need = 5 kg/man/ day

Sea time = day

Wprov= ton

~ Freshwater needs

a. Eat and drink of crew

b. Washing and sanitary

c. Cook

d. Cooling Engine

In the design of planned:

Sea time = day

Loading and unloading = 2 day

Based on data used to determine the need is :

a. Eat and drink of crew (Wfwd)

Consumption = 10 kg/man/day

(estimation between 10 - 20 kg/man/day)

Total time = Sea time + loading unloading

= 7 day

∑ Water Needs = 1,4 ton

b. Shower and wash (WFS)

Consumption = 60 kg/man/day(estimation between 60 - 200 kg/man/day)

Total time = Sea time + loading unloading

= 7,0 day


c. Cooking (Wfwc)

Consumption = 4 kg/man/day(estimation between 3 - 4 kg/man/day)

Totalize time = Sea time + loading unloading


LWT dan DWT

0,50

Supplies of fresh water on the ship in this case is calculated on the

maximum demand conditions, namely when the ship set sail and when the

ship was doing loading and unloading. The need for fresh water on board is

divided over the need:

5

1,4

5,00

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= 7,0 day


d. Cooling engine

- Cooling main engine (Wfwj)

Taken (c) = 5 kg/kWh

(cooling requirement estimated between 5 - 7 kg/kWh)

Wfwj = P x c x (S/Vs) x 10-6

= ton

- Cooling auxiliary engine (Wfwae)

Taken (c) = kg/kWh

(cooling fresh water requirement estimated between 0,1 - 0,2 Wfwj)

Wfwae = Wfwj x c

= ton

Wfw = Wfwd + Wfws + Wfwc + Wfwj + Wfae

= ton

W total provision = WHFO + WMDO + WLO + Wcrew + Wprov + Wfw

= ton

Calculation of Payload

Payload = DWT - W total provision

= ton

Type of container carried = @18 ton (20')

Jumlah kontainer = Payload /container

= Container

So,total 20' container which can be carried is 308 TEUS

308

From the calculations above requirement can be further calculated the total

weight by using the following calculation:

144,64

After knowing the total weight of supplies and deadweight ship, the vessel

can be calculated the amount of payload:

5538,8

2,34

0,15

0,35

After knowing the weight of fresh water for each - each needs it, can know

the total requirement of fresh water during travel and handling that is equal

to:

13,05


LWT dan DWT

calculation of displacement, lwt and dwt

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