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Introduction To Hydrostatics

This document discusses hydrostatics and stability as it relates to ship design. It covers topics like principal dimensions, form coefficients, flotation, hydrostatic quantities, stability, and regulations. Dimensional parameters like block coefficient, midship section coefficient, prismatic coefficient, and waterplane area coefficient are defined. Methods for representing hull form like the table of offsets, lines plan, surface modeling, and rendered views are presented. Examples are given for calculating form coefficients from ship dimensions and displacement.

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Euclides Cagnini
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229 views21 pages

Introduction To Hydrostatics

This document discusses hydrostatics and stability as it relates to ship design. It covers topics like principal dimensions, form coefficients, flotation, hydrostatic quantities, stability, and regulations. Dimensional parameters like block coefficient, midship section coefficient, prismatic coefficient, and waterplane area coefficient are defined. Methods for representing hull form like the table of offsets, lines plan, surface modeling, and rendered views are presented. Examples are given for calculating form coefficients from ship dimensions and displacement.

Uploaded by

Euclides Cagnini
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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07/10/2014

Hydrostatics and Stability


Dr B S Lee
b.s.lee@strath.ac.uk
Tel 0141 548 4782
HD 2.33

Hydrostatics
Statics
branch of mechanics
physical systems in static equilibrium
Hydro
water or water environment
Hydrostatics
studies of fluid at rest

07/10/2014

Stability
the ability of the vessel to return to the normal
operating attitude, when disturbed from this
attitude, without endangering itself or the
cargo and human life it carries

Topics Covered
Principal dimensions, form coefficients and
representation of hull form
Flotation and hydrostatic quantities
Numerical integration
First moments
Second moments
Longitudinal stability
Transverse stability
Dynamical stability and regulations
Introduction to damage stability

07/10/2014

VLCC

Bulk Cairrier

07/10/2014

Cruise Ship

Ship - Key Parts

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Longl Dimensions

Longl Dimensions

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Longl Dimensions

Transverse Dimensions

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Transverse Dimensions

Volumes and Weights

volume displacement in m3

mass displacement in tonnes


Lightship in tonnes
Deadweight (DWT) in tonnes

= LSHIP + DWT

07/10/2014

Volumes and Weights contd


=

= 1.0 tonne/m3 fresh water


1.025 tonnes/m3 salt (sea) water
GT (Gross tonnage) = K x V, K = 0.2 + 0.02 log10 V
1 GRT = 100 cuft = 2.83168 m3
0.5919 GT = 1 GRT

Block Coefficient (CB)

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Maximum Section Coefficient (CX)

Midship Section Coefficient (CM)

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Midship Section Coefficient (CM)

CM =

AM
B T

Usually
CM =CX

Prismatic Coefficient (CP)

10

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Waterplane Area Coefficient (CW)

CW =

AW
LWL B

Vertical Prismatic Coefficient (CVP)

CVP =

AW T

11

07/10/2014

Summary

L B T
A
CM = M
B T

C B = C P CM
CP =
L AM
CB =

CW =

AW
L B

Typical Form Coefficients

12

07/10/2014

Typical Form Coefficients


CB

CM

CW

Ex. 1

LWL
B
TM

AM
AW

14.251m
4.52m
1.908m
58.536m3
6.855m2
47.595m2

Find CB, CWL, CM and CP

13

07/10/2014

Ex. 2
Lpp = 205.74 m
B = 28.955 m

Complete the table.

Co-ordinate System

Origin usually at
(midship, WL),
(midship, BL),
(AP, WL),
(AP, BL)
Right hand rule
+x fwd
+z up or down

14

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Representation of Hull Form


Table of offsets
Line plan
Surface modelling
Rendered view

Table of Offsets

15

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Table of Offsets

Stations

16

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Station Numbering
0 at FP and 10 (or 20) at AP in USA
0 at AP and 10 (or 20) at FP in the rest of the
world
Often half stations and quarter stations or
more divisions near stern and bow where
sections change shape

Waterlines

17

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Buttocks

Lines Plan

18

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Lines Plan

Body Plan

Curved

Mixture

Simple
Structure

Irregular
Structure

Flat
Regular
Structure

19

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Surface Mesh Modelling

Curved

Mixture

Simple
Structure

Irregular
Structure

Flat
Regular
Structure

20

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Rendered Display

Other Ratios
B/T (beam-to-draught ratio)
L/B (length-to-beam ratio)
Length coefficient of Froude, or lengthL
displacement ratio

volumetric coefficient

L3

21

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