GHS provides two special tank types for the purpose of modeling the effects of the extra burden of water on deck due to waves.

The first, FLOODED PLUS, is an extension of the FLOODED type. It raises the flooded waterplane above the external waterplane by an amount such that the increased volume is equal to the volume indicated by the LOAD setting.

The other type is called DECK. It is similar to the DAMAGED type with LOAD = 0 and an additional head of water added to that of the external waterplane. The parameter /HW: must be included with the TYPE command in order to specify the value of the additional head.

Following is a run which demonstrates the use of these types to model the two methods of treating water on deck.

macro makeship

clear

enter pm

create hull

ends 0 100

top 20

bot 0

out 10

//

create deck.c

ends 15 85

bot 8

fit hull

//

write testwod.gf

quit

/

macro interp `%1=x, %2=x1, %3=y1, %4=x2, %5=y2, %6=result var name

if %1<%2 then set %6 = %3 | exit

if %1>%4 then set %6 = %5 | exit

variable t

set t = %4 minus %1 times %3

set %6 = %1 minus %2 times %5 plus {t}

set t = %4 minus %2

set %6 = {%6} div {t}

/

macro wod

type = flood

solve

variable hw,f,v

variable (string) u

set u = "{wunit}"

unit mt

.interp {HEIGHT}, .3, .5, 2, 0, "hw"

.interp {hs}, 1.5, 0, 4, 1, "f"

set hw = {hw} times {f}

if %1="NEU" then type = deck /hw:{hw}

mac t

type = intact

heel = 0 | trim = 0

load = .5

solve depth

set f = {HEIGHT}

set v = {TVOLUME}

set f = {f} minus 0.1

load = height:{f}

solve depth

set v = {TVOLUME} minus {v} times 10

\\Deck area is {v} sq. meters\

set v = {v} times {hw}

contents = fw

load = weight:{v}

type = flood plus

//

if %1="POE" then .t

unit {u}

solve

/

macro stat

\With water on deck, wave height: {hs} meters hw: {hw} meters\

status

/

macro ra

heel = 0

ra /area /nowarn

/

`===== Start of project commands ======

`Get geometry

project testwod

if fexist {project}.gf then read else .makeship

report

`Set ship weight and C.G.

draft = 4.5

vcg = 5

solve weight, lcg

`Set point of damage

variable pod

set pod = "50a, 10s, 8" `Point of damage, also used to determine freeboard.

refpt (hull) = {pod}

`Select deck to be flooded

tank deck.c

refpt = {pod}

type = flood

`Induce heeling moment

tcg = 0.5

\\==== Initial condition without water on deck: ====\

solve

status

`Set wave height

variable hs

set hs = 2.75 `Wave height in meters

macro case

page

\\%2 method\

.wod %1

.stat

.ra

/

.case neu "Northern European"

.case poe "Panel-of-Experts"

print preview report off end

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Copyright (C) 2011 Creative Systems, Inc.