K

K K = KEEL= KEEL

M MM = META CENTER = META CENTERKMKM = HEIGHT OF = HEIGHT OF

META CENTERMETA CENTERG GG = CENTER OF GRAVITY = CENTER OF GRAVITY

KGKG = HT OF CENTER = HT OF CENTEROF GRAVITYOF GRAVITY

GMGM = METACENTRIC HT = METACENTRIC HTB

BB = CENTER OF BUOYANCY = CENTER OF BUOYANCYKBKB = HT OF CENTER = HT OF CENTER

BUOYANCYBUOYANCYBM BM = METACENTRIC RADIUS= METACENTRIC RADIUS

G = BG = BV/L FLOATSV/L FLOATSG > BG > BV/L SINKSV/L SINKS

STABILITY NOMENCLATURESTABILITY NOMENCLATURE

K

M

G

B

• THE POS. OF THE POS. OF KK IS FIXED IS FIXED• THE POS OF THE POS OF MM VARIES VARIES

W/ THE DRAFT OF VSL.W/ THE DRAFT OF VSL.G

G

• GG MOVES MOVES TOWARDSTOWARDS WT. LOADEDWT. LOADED

G

G

• GG MOVES MOVES AWAY FROMAWAY FROMWT. DISCHARGEWT. DISCHARGE

• GG MOVES MOVES PARALLELPARALLEL TO THE DIRTO THE DIR. OF THE WT. OF THE WT

BEING SHIFTEDBEING SHIFTED

• B MOVES TOWARDSB MOVES TOWARDSTHE THE LOW SIDE OFLOW SIDE OFINCLINED V/LINCLINED V/L

G

B

G

HEELHEEL

DUE TO EXTERNAL DUE TO EXTERNAL FORCEFORCE

LOW LOW SIDESIDE

LISTLISTG G OFF THEOFF THE

CENTER LINECENTER LINE

DUE TO UNEVENDUE TO UNEVEN

WEIGHTWEIGHT

K

GM

DBT EMPTYDBT EMPTY

TST FULLTST FULL TST FULLTST FULLSTABLESTABLE

KM > KGKM > KG

M IS ABOVE GM IS ABOVE G

GM IS POSITVEGM IS POSITVE

K

GM

DBT EMPTYDBT EMPTY

TST FULLTST FULL TST FULLTST FULLNEUTRALNEUTRAL

KM = KGKM = KG

M & G COINCIDESM & G COINCIDES

GM = ZEROGM = ZERO

K

GM

DBT EMPTYDBT EMPTY

TST FULLTST FULL TST FULLTST FULLUNSTABLEUNSTABLE

KG > KMKG > KM

G IS ABOVE MG IS ABOVE M

GM IS NEGATIVEGM IS NEGATIVE

K

GM

DBT FULLDBT FULL

TST EMPTYTST EMPTY TST EMPTYTST EMPTYSTABLESTABLE

G MOVES TOWARDSG MOVES TOWARDS

WEIGHT ADDEDWEIGHT ADDEDG MOVES AWAY FROMG MOVES AWAY FROMWEIGHT DISCHARGEDWEIGHT DISCHARGED

K

G

M

B

M

G Z

UPRIGHTUPRIGHT INCLINEDINCLINED

K

B

GZGZ

RIGHTING MOMENT RIGHTING MOMENT

POSITIVE GMPOSITIVE GM POSITIVE GMPOSITIVE GM

= RIGHTING ARM OR = RIGHTING ARM OR RIGHTING LEVERRIGHTING LEVER

= GZ= GZ X DISPX DISP

K

G

M

BM

GZ

UPRIGHTUPRIGHT INCLINEDINCLINED

K

B

NEG. GZNEG. GZ

NEGATIVE GMNEGATIVE GM

= CAPSIZING ARM= CAPSIZING ARM

NEGATIVE GMNEGATIVE GM

K

G M

B

M GZ

UPRIGHTUPRIGHT INCLINEDINCLINED

K

B

GZ GZ

GM = ZEROGM = ZERO

(RIGHTING ARM)(RIGHTING ARM)

GM = ZEROGM = ZERO

= ZERO= ZERO

M

Z

K

B

RELATIONSHIP BET. GM AND GZRELATIONSHIP BET. GM AND GZ

Z

G (NEGATIVE GM)(NEGATIVE GM)

G

(POSITIVE GM)(POSITIVE GM)

G Z ZERO GMZERO GM

M

K

EFFECT OF DIFF. GM ON THE PERIOD OF ROLLEFFECT OF DIFF. GM ON THE PERIOD OF ROLL

ZG

G ZG IS HIGHG IS HIGHGM IS SMALLGM IS SMALLSMALL GZSMALL GZSLOW ROLLSLOW ROLL

TENDERG IS LOWG IS LOWGM IS LARGEGM IS LARGELARGE GZLARGE GZFAST ROLLFAST ROLL

STIFF

G

TANK EMPTYTANK EMPTYNO FREE SURFACENO FREE SURFACE

TANK FULLTANK FULLNO FREE SURFACENO FREE SURFACE

M

G

TANK NOT FULL TANK NOT FULL = FREE SURFACE= FREE SURFACE

VERTICAL RISE OF GVERTICAL RISE OF G = REDUCTION IN GM= REDUCTION IN GM

M

G

WATERTIGHTWATERTIGHTSUBDIVISIONSUBDIVISION

M

G IS STILL EFFECTIVELYG IS STILL EFFECTIVELYRAISED BUT ONLY BY RAISED BUT ONLY BY 1/41/4COMPARED TO WHEN THECOMPARED TO WHEN THETANK WAS UNDIVIDEDTANK WAS UNDIVIDED

SUBDIVISON OF TANKSSUBDIVISON OF TANKS

WITH 2 BULKHEADS THE EFECTS IS REDUCEDWITH 2 BULKHEADS THE EFECTS IS REDUCEDTO TO 1/91/9. THE MORE BULKHEADS THE LESS EFFECT. THE MORE BULKHEADS THE LESS EFFECT

GM

PRACTICAL WAYS OF REDUCINGPRACTICAL WAYS OF REDUCINGTHE FREE SURFACE EFFECTTHE FREE SURFACE EFFECT

WHERE POSSIBLE,WHERE POSSIBLE,TANKS EITHERTANKS EITHEREMPTY EMPTY OR FULLOR FULL

MIN. NO. OF DAILYMIN. NO. OF DAILY SERVICE TANKSSERVICE TANKS

BILGES PUMPED OUTBILGES PUMPED OUT

FREEING PORTS,FREEING PORTS,SCUPPERS, UNOBSTRUCTEDSCUPPERS, UNOBSTRUCTED

IN USEIN USE

FREE SURFACE EFFECTFREE SURFACE EFFECT