INTRODUCTION TO NAPA

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Contents

Introduction to NAPA System. Sub systems of NAPA. Starting a new NAPA session. Starting a new project in NAPA. The Text Editor and Geometry Window of

NAPA. Commands in NAPA Designing ship with NAPA The Hull Surface Editor of NAPA

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Introduction to NAPA System

NAPA- Naval Architectural PAckage.Handling all types of floating structures.All geometry definitions based on a 3D

ship model.Single database,multi user environment.

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Contd…..

Wide range of naval architectural calculations.

NAPA is originally a command oriented program.

Also have detailed and dynamic GUI.NAPA contains several sub systems-

that perform various tasks (functions related to ship design).

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Subsystems of NAPA

Mainly 2 subsystems Application Subsystems - Performs

functions related to ship design (Hydrostatics, Damage stability, Loading conditions etc).

Auxiliary Subsystems –Performs functions needed for internal functions of the system (project administration, database management, graphic calculations etc).

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Application sub systemsSHIP MODEL SM

GEOMETRY GM

HYDROSTATICS HD

CAPACITIES CP

LOADING CONDITIONS LD

STABILITY CRITERIA CR

DAMAGE STABILITY DA

LAUNCHING LN

INCLINING INC

WEIGHT CALCULATION WG

GRAIN STABILITY GS

CONTAINER LOADING CL

SHIP HYDRODYNAMICS SH

SEA KEEPING SHS

MANOEUVRING SHM

Table-1 List of application subsystems and their abbreviations

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Auxiliary sub systems

Table-2 List of auxiliary subsystems and their abbreviations

DATABASE MANAGEMENT DB

DYNAMIC MEMORY MANAGEMENT DM

BASIC GEOMETRY GB

GRAPHICS GR

ERROR HANDLING ER

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Starting a new NAPA session

• Click on the NAPA icon.• Give the

User id : ADMIPassword :and you move on to the main window of NAPA.

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NAPA Main window

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Creating a new project in NAPA

• From NAPA main window,

File Create new project

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Text editor window

• From NAPA main window,

Tools Text editor

• Commands can be given in the

text editor window

• To open an existing file,

File Open Select filename

• After typing all the commands, save the file and run it.

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Geometry window

• To view the output• Path is :

Napa Main window

Tools

Geometry window.

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How to give commands in NAPA ?

• By default, NAPA uses right handed coordinate system.

X longitudinal direction.

Y transverse direction.

Z heights.

• To define a curve, keyword ‘cur’ is used.

• -/ operator to define a straight line between the given two points

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* Operator to define the curve to follow the given order of input of points.

/<angle> curve should approach the next point at the given slope.

<curve1>/<curve2> point of intersection of given two curves.

Keyword used to define a surface is ‘sur’.

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Designing a ship with NAPA

• Combination of forward part, parallel mid body and the aft part gives the complete hull.

Forward part Parallel mid body Aft part

Complete hull 15

Example:'DEFINITION OF FORWARD PART'

cur frf

x 62

yz * (0 0) -/ (4.7 0) (6.5 1.8) /- (6.5 11.5)

cur stem

y 0

xz * (62 0) -/ (80 0) (84 2.2) (82.2 4) (81.7 4.4) (81.9 5) -/ (85.5 11.5)

cur deckf

z 11.5

xy * frf -/ (72 6.5) (75 6.3) (84 2.5) stem

cur fsf

y 6.5

xz * frf/z=1.8 (65 2.2) deckf/x=72

cur fbf

z 0

xy * frf/y=4.7 (65 4.65) stem/x=80

sur hullf

thr frf stem deckf fsf fbf

ok

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• Similarly, give commands to create aft part (hulla) and the parallel mid body (hullm).

• Now, combine all the three parts to form the complete hull.• Example :

'DEFINITION OF HULL‘

sur hull

com hulla hullm hullf

ok

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Hull surface editor

• Intended for the modification of hull surfaces or any surface defined by a curve grid.

• Path is :

Napa main window Tools Hull surface editor• Hull fairing and patch creation can be done here.• A patch is an area which is limited by the nearest curves in the grid.

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Forward part

Parallel mid body

Aft part

Complete hull 19

• To create stations / buttock lines / waterlines :

Hull surface editor Curve Create new curve.

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• To fair the curve.

Click the curve definition tool and edit the command.

Before fairing

After fairing

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