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STABILITY INFORMATION BOOKLET

MCA SAILING CODE VESSEL

DATE: xx/xx/200X

K N

G Z

M

WATER LINE θ

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CONTENTS General Particulars Diagram to show Draught mark locations Datum Reference Information Unit Conversion Table Arrangement of Tanks Sample Tank Capacity Table Notes to the Master General instructions Tank usage and free surface moments Master’s shipboard procedures Precautions against capsize Notes on use of KN Curves Angles of down flooding General Stability Requirements Sample form for calculating Loading Condition Explanation and notes on completing Sample Stability Form Freeboard Loadline Marks Loading Conditions Hydrostatic Properties Cross Curve Stability Plot Appendix I Inclining Experiment Results Appendix II Minor Modifications

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GENERAL PARTICULARS Ship’s Name Official Number Port of Registry Owner’s name and address ------------ ------------ ------------ Classification Society Builder Yard Number Date of keel laying Dimensions Length overall (LOA) m Length between perpendiculars (LBP) m Max Beam m Depth m Assigned Freeboard m Max Summer loaded draught m Max Displacement at Summer Load Draught T Gross Tonnage

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DIAGRAM TO SHOW DRAUGHT MARK LOCATIONS DATUM REFERENCE INFORMATION Longitudinal datum = amidships Transverse datum = centreline Vertical datum = base line Aft Perpendicular = ? metres aft amidships Fwd Perpendicular = ? metres fwd amidships Aft Draught Marks = X metres aft amidships Fwd Draught Marks = Y metres fwd amidships

LBP (m)

Aft Draught Mark Fwd Draught Mark

AP FP

X(m) Y(m)

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UNIT CONVERSION TABLE MULTIPLY BY TO CONVERT

FROM TO OBTAIN

0.039370 mm inches 25.4 0.39370 cm inches 2.54 3.2808 m feet 0.3048 2.2046 KG lbs 0.45359 0.00098421 KG Tons (2240 lbs) 1016.0 0.98421 Tonnes (1000 KG) Tons (2240 lbs) 1.016 2.4999 Tonnes per cm Tons per inch 0.40002 8.2017 Tonnes metres units

(MCTC) Ton feet units (MCTI)

0.12193

187.98 Metre Radians Foot Deg 0.0053198 TO OBTAIN TO CONVERT

FROM MULTIPLY BY

Relationships between Weight and Volume 10mm cubed = 1 cubic cm 1 cubic cm of fresh water (S.G. = 1.0) = 1 gram 1000 cubic cm of fresh water (S.G. 1 = 1.0) = 1 kg (1000grams) 1 cubic meter of fresh water (S.G. 1 = 1.0) = 1 tonnes (1000kg) 1 cubic meter of salt water (S.G. 1 = 1.025) = 1.025 tonnes (1025kg) 1 Tonne of salt water (S.G. 1 = 1.025) = 0.975 cubic metres 1 cubic metre = 35.316 cubic feet 1 cubic foot = 0.0283 cubic metres

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ARRANGEMENT OF TANKS 1. Fuel Oil Tank Stb

2. Fuel Oil Tank Port

3. Fresh Water Tank Stb

4. Fresh Water Tank Port

5. Grey Water Tank

4 3

2 1 5

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SAMPLE TANK CAPACITY TABLE Tank Name XX Contents FW/FO etc Capacity Max YY

Sounding Depth (m)

% Full Mass (MT)

VCG (m)

LCG (m)

FSC (m)

1 100 5.2 X Y Z 0.9 90 4.5 X Y Z 0.8 80 3.8 X Y Z 0.7 70 3.2 X Y Z 0.6 60 2.2 X Y Z 0.5 50 1.5 X Y Z 0.4 40 1.09 X Y Z 0.3 30 0.85 X Y Z 0.2 20 0.56 X Y Z 0.1 10 0.23 X Y Z

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NOTES TO THE MASTER 1. General Instructions A stamped, approved copy of this booklet must be kept on board the vessel at all times. It must also be complete, legible and readily available for use. If this booklet is lost or becomes unusable a replacement copy of the approved booklet must be obtained immediately. MCA operating Restrictions (if any). Min liquids to be carried in arrival condition (if any). The loading conditions shown in this booklet represent typical service conditions. It is emphasised that a separate calculation is necessary for all differing conditions of loading. Master’s Shipboard procedures are to be followed at all times. 2. Tank Usage and Free Surface Moments Provided a tank is completely filled with liquid no movement of the liquid is possible and the effect on the ship’s stability is pr ecisely the same as if the tank contained solid material. Immediately a quantity of liquid is withdrawn from the tank the situation changes completely and the stability of the ship is adversely affected by what is known as the ‘free surface effect’. This adverse effect on the stability is referred to as a ‘loss in GM’ or as a ‘virtual rise in VCG’ and is calculated as follows:

EQ.1 ( )

( )TonnesntDisplacemeVesselmTonnesMmtSurfaceFree

GMofLoss =

When preparing loading conditions, it is to be noted that free surface effects must be allowed for the maximum number of tanks which are slack or shortly to become slack in that given loading condition. This will mean that, for departure conditions all main fuel tanks as well as fresh water tanks are considered to be slack. The number of slack tanks should be kept to a minimum. Where port and starboard tanks are cross coupled, such connection should be closed at sea to minimise the reduction in stability. Where ballast tanks are used they should be ‘pressed full’ or ‘empty’ as far as possible. Dirty water in the bilge’s must be kept to a minimum. 3. Master’s ship board procedures Internal sliding WT doors, may be left open, but should be closed when risk of hull damage and flooding increases eg, in fog, in shallow rocky waters, in congested shipping lanes, when entering and leaving port and at any other time the master considers appropriate. Sliding WT doors should be checked daily to ensure that nothing has been placed in way of the door or where it might fall into the opening and prevent the door from closing.

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4. Precautions against capsize Before a voyage commences care should be taken to ensure large items of equipment and stores are properly stowed to minimise the possibility of both longitudinal and transverse shifting under the effect of acceleration caused by pitching and rolling, or in the event of a knockdown to 90 degrees. All external hull doors and flush hatches (list them) are to be closed and secured. In adverse weather conditions and where there is the possibility of encountering a severe gust, squall or large breaking wave, all exposed doors, hatches, skylights, vents, etc. should be closed and securely fastened to prevent the ingress of water. Storm boards etc. should be erected and fitted. The number of slack tanks should be kept to a minimum. Where port and starboard tanks are cross coupled, such connection should be closed at sea to minimise the reduction in stability. Compliance with the stability criteria indicated in the booklet does not ensure immunity against capsizing regardless of the circumstances or absolve the Master from his responsibilities. Masters should therefore exercise prudence and good seamanship having regard to the season of the year, experience of the crew, weather forecasts and navigational zone, and should take appropriate action as to the speed, course and sail setting warranted by the prevailing conditions. The amount of sail carried is at the discretion of the Master and his decision will have to take into account many factors. In assessing the risks of downflooding, the Master should be guided by Figures 1 and 2 below.

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Notes on use of KN Curves KN curves for displacements of X to Y tonnes are presented for angles of heel at intervals between 0 and Z degrees. To obtain righting arm (GZ) curves at a given displacement, the following equation should be used: θsinKGKNGZ −= This enables the value of GZ to be calculated at each of the heel angles presented, and subsequently plotted as in the loading conditions presented herein. Angles of down flooding This is the angle of heel at which progressive down flooding of the vessel will occur due to the immersion of an opening.

Description Area of Opening (m2)

ANGLES OF IMMERSION (degs)

100% Consumable 10% Consumable

Saloon X A 42 40 Crew Y B 46 40 Gallery Z C 30 29

K N

G Z

M

WATER LINE θ

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Critical Flooding is deemed to occur when the lower edges of openings have an aggregates area in m2, greater than;

( )

1500TonnesntDisplacemeVessel

ngDownfloodi =

The master should note that the presence of the vent and skylights significantly reduces the ability of the vessel to withstand down flooding and with these opening securely closed the safety of the vessel is enhanced considerably. Figure 1 shows the maximum recommended steady heel angle to prevent downflooding in gusts. Operation of the vessel at a greater heel angle would result in downflooding if it were to encounter the strongest possible gust in the prevailing turbulent airstream, which could exert a heeling moment equal to twice that of the mean wind. Figure 2 shows the maximum recommended steady heel angle to prevent downflooding in squalls. Operation of the vessel at a greater heel angle would result in downflooding if it were to encounter the heeling effects of a squall arising from a storm or frontal system which may result in a heeling moment many times greater than that of the mean wind. For this reason the Master should have regard to the maximum steady heel angle curves presented for a range of squall speeds. By using the readings from his inclinometer and anemometer a master is able to determine the degree of risk of capsize in gusts or squalls which may occur in the prevailing weather system. He may then decide to shorten sail together with other actions he considers necessary.]

Additional care should be taken when sailing with the wind from astern, as in the event of the vessel broaching or a gust striking the vessel on the beam, the heeling effects of the wind may be increased to a dangerous level when the preceding heel angle was small.

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Maximum Steady Heel Angle to Prevent Downflooding in Gusts

GUSTING CONDITIONS When sailing in a steady wind the vessel heels to the angle at which the heeling arm curve intersects the GZ curve. When struck by a gust the heel angle will increase to the intersection of the gust heeling arm curve with the GZ curve. The heeling moment increases in proportion to the square of the apparent wind speed. Operation of the vessel at a mean heel angle not greater than 27 degrees ensures significant downflooding openings would not be immersed if it were to encounter the strongest gust in the prevailing turbulent airstream which could exert a heeling moment equal to twice that of the mean wind. i.e. mean apparent wind has increased in velocity by 1.4. Footnote: If the 10% consumable condition is more onerous this should be shown.

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Curves of maximum Steady Heel Angle to Prevent Downflooding in Squalls

SQUALL CONDITIONS Curves of the maximum steady heel angle indicate the range of mean or steady heel angles beyond which the vessel will suffer downflooding in the event of a squall. Operation of the vessel in cyclonic conditions particularly in the hours of darkness, where severe squalls are imminent requires the recommended maximum steady heel angle to be reduced depending on the mean apparent wind speed in accordance with the curves presented above.

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Examples Showing the Use of the Maximum Steady Heel Angle Curves

Example A the yacht is reaching, with a steady apparent wind speed of 16 Knots. The mean heel angle is 15 degrees. Forecasts and visible cumulo-nimbus clouds suggest squalls may be imminent. By plotting the heel angle and wind speed (point A in figure 3) the indication is that the vessel will be in danger of heeling to the downflooding angle in squalls of 30 knots. In order to increase safety from downflooding, say, to withstand squalls of up to 45 knots, sails should be handed or reefed to reduce the mean heel angle to 7 degrees (point AI in Figure 3 ) or less. Example B The yacht is beating in gusty conditions with a mean apparent wind speed of 30 knots. The mean heel angle is 20 degrees. No squalls are expected. The heel angle is significantly less than 27 degrees, the maximum recommended steady heel angle, and there is therefore a good safety margin against downflooding in a strong gust. Plotting these values of wind speed and heel angle (point B in Figure 3) also indicates that the vessel would not be vulnerable to downflooding in a squall unless it resulted in a wind speed in excess of about 50 knots. There is thus no need to reduce sail area on the grounds of stability.

Footnote: Appropriate examples should be presented for the master, to enable him to interpret the meaning of these curves and understand their use.

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Notes for Consultants on the Derivation of the maximum Steady Heel Angle to Prevent Downflooding in Gusts

GZf

HA1 = cos1.3

�f

where HA1 is the magnitude of the actual wind heeling lever at 0 degrees which would cause the ship to heel to the downflooding angle ��� f) or 60 degrees whichever is least GZf ������� ��������������� ������������� "!�#$�%��'&(�)���+*$�-,�.����/�$�0*0�1.�23&(.�24�/'5 f or 60 degrees whichever is least HA2 6�7�8�9�:<; :>=@?BAC6�?0DE9�:@:GF/6�?0HB=@I�;J=�8K=@?4LM=�?�H4F�:ONPD4:>HQIR:S:G7 = 0.5 x HA1 x cos1.3 N

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Notes for Consultants on the Derivation of Curves of Maximum Steady Heel Angle to Prevent Downflooding in Squalls The wind heeling moment is proportional to the wind pressure, and to the apparent wind speed squared. It is also dependent upon the area, height, shape and camber of the sails, the apparent wind direction and the prevailing wind gradient. As a sailing vessel heels the wind heeling moment decreases and at any heel angle ( T U)V�W(X�YMWSW@Z\[^]`_-a�bRc/dQe4X�Ugf�Z�hji$[ h$W>dQbkW>W>l�c1X is related to the upright value by the function:- HM = HM0 cos1.3 m YBe�W@bkW HM0 is the heeling moment when upright. The heel angle of a sailing vessel corresponds to the intersection of the heeling arm (HA) curve with the righting arm (GZ) curve, where HA = HM / displacement. When subjected to a gust or squall the vessel heels to a greater angle where the heeling arm curve corresponding to the gust wind speed intersects the GZ curve. Thus for a given heel angle a heeling arm curve may be deduced and for a given change in wind speed the resulting change in heel angle can be predicted.

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The vessel will suffer downflooding when the heeling arm curve intersects the GZ curve at the downflooding angle. The situation is illustrated in the diagram where the “heeling arm in squall” curve intersects the GZ curve at 52 degrees. If we assume a scenario where sufficient sail is set to heel the vessel to the downflooding angle (60 degrees should be used if the downflooding angle exceeds that value) in a squall of, say 45 knots, then we can predict the wind speed which would result in any lesser heel angle in these circumstances. The upright heeling arm in the squall (HA1) is derived from:-

GZf

HA1 = cos1.3 n f

If we consider a steady heel angle prior to the squall of 20 degrees we can derive

similarly the corresponding value of the upright heeling arm HA2 :-

GZ20

HA2 = cos1.3 20

The ratio HA2/HA1 corresponds to the ratio of wind pressures prior to the squall and in the squall thus for a squall speed (V1) of 45 knots resulting in downflooding, the wind speed prior to the squall (V2) which would result in a heel angle of 20 degrees would be:- V2 = V1

HA2

V2 = V1 ( HA1

) 0.5

In this example, which is illustrated in the diagram, n f = 52 degrees GZf = 0.725 metres HA1 = 1.362 metres GZ20 = 0.464 metres HA2 = 0.503 metres Hence V2 = 27.4 knots Thus when sailing with an apparent wind speed of 27.4 knots at a mean heel angle of 20 degrees, an increase in the apparent wind speed of 45 knots from the same apparent wind angle would result in downflooding if steps could not be taken to reduce the heeling moment.

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These values correspond to a point on the 45 knot squall curve in Figure 2 , which was derived from a series of such calculations using different steady heel angles. Similarly, the curves for other squall speeds were derived using different values for V1. These calculations should be performed for both loading conditions and the results corresponding to the worst case (i.e. the lowest maximum steady heel angles) presented in the booklet.

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General Stability Requirements It is import ant to ensure that in any sailing condition the stability of the vessel complies with the following minimum criteria of section 11.2 of the Code of Practice for Large Commercial Sailing and Motor Vessels. 1. Curves of static stability (GZ curves ) for at least the Loaded Departure with

100% consumables and the Loaded Arrival with 10% consumables should be produced.

2. The GZ curve required by 1 should have a positive range of not less than 90o. 3. The angle of steady heel should be greater than 15o. The angle of steady heel is

obtained from the intersection of the “derived wing heeling lever” curve with the GZ curve required by 1.

θ3.15.0 COSWLOdwhl ××=

F

F

COSGZ

WLOθ3..1=

WLO Is the magnitude of the actual wind heeling lever at zero degrees which cause the

vessel to heel to the ‘down flooding angle’ ( o p ) or 60 degrees whichever is least. GZF Is the lever of the vessel’s GZ at the down flooding angle or 60 degrees,

whichever is least. q r

Is the angle at which the derived wind heeling curve intersects the GZ curve

0o

dwhl

15o 45o 60o 75o 90o 115o 30o

Angle of heel (degs)

GZ WLO

θF θD

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The curves of righting levers (also known as GZ curve), for each condition of loading should be obtained at the trim shown in the condition by interpolation between the appropriate sets of trimmed cross curves (KN curves). Sample form for calculating Loading Condition TABLE 1

Item

Load %

WT MT

LCG m aft

amidships

L Mmt m –MT

VCG m -BL

V Mmt m-MT

FSM m-MT

Passengers and effects - Crew and Effects - Provisions and stores Deck A - Provisions and stores Deck B - Provisions and stores Deck C - Provisions and stores Deck D - Jet Skis etc - Tender -

Tanks Capacity mt

Load %

WT MT

LCG m aft

amidships

L Mmt m –MT

VCG m -BL

V Mmt m-MT

FSM m-MT

1 Fuel Oil Tank Stb A 2 Fuel Oil Tank Port B 3 Fresh Water Tank Stb C 4 Fresh Water Tank Port D 5 Grey Water Tank E 6 Aft Ballast Tank Stb F 7 Aft Ballast Tank Port G 8 Lub Oil Tank H

Total Dead Weight

-

Lightship Weight I J K L M - Displacement (MT)

Note: Lightship weight includes x, y and z items TABLE 2

Stability Calculation Fwd Draught METRES Aft Draught METRES Trim METRES Displacement MT VCG METRES KMT METRES GMT (solid) METRES FSC METRES GMT (fluid) METRES

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TABLE 3

Trim Calculations LCF Draught (above base line) METRES LCG (fwd/aft of amidships) METRES LCF (fwd/aft of amidships) METRES LCB (fwd/aft of amidships) METRES Trim lever METRES MCTC MT m/cm Trim METRES LBP METRES Fwd Draught METRES Aft Draught METRES Explanation and notes on completing Sample Stability Form. Table 1 Calculating the Displacement and Centres of gravity • Fill in the weights in column 3 (WT). • Fill in the longitudinal and vertical centres of gravity in columns 4 (LCG) and

6(VCG) respectively. • Multiply the weight of each item by its centre to get the longitudinal and vertical

moments and enter moments in column 5 (L Mmt) and Column 7 (V Mmt). • Record all the tank loads and enter the % into column 2 (load %) • From the tank capacity plan enter the tank weights into column 3 (WT), LCG’s into

column 4, VCG’s into column 6 and FSC into column 8. • Multiply the weight of each tank by its centre to get the longitudinal and vertical

moments and enter moments in column 5 (L Mmt) and Column 7 (V Mmt). • Sum up columns 3,5 and 7 and enter total in Dead Weight row. • Add Dead Weight mass to Light Ship mass and enter new total in Total Displacement

row column 3. • Add Dead Weight LCG Mmt to Light Ship LCG Mmt and enter new total in Total

Displacement row column 5. • Divide Total Displacement row column 5 by Total Displacement row column 3 to

calculate overall estimate of LCG location for loading condition. Enter calculation into Total Displacement row column 4.

• Add Dead Weight VCG Mmt to Light Ship VCG Mmt and enter new total in Total Displacement row column 7.

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• Divide Total Displacement row column 7 by Total Displacement row column 3 to calculate overall estimate of VCG location for loading condition. Enter calculation into Total Displacement row column 6.

• Sum up column 8 (FSC) and enter total into Total Displacement row column 8. Table 2 Calculating the Stability • Transfer the value of the overall VCG from table 1 and enter it in table 2. • Record fwd and aft draught estimates in table 2. • Subtract fwd draught from aft draught (noting if trim is stern down or bow down),

and enter trim value in table. • Using the trim estimate and the displacement value calculated in Table 1 determine

hydrostatics values of KMT, LCB, MCTC, LCF and LCF draught, and enter in table 3.

• Subtract the overall VCG value in table 1 from KMT to obtain GMT solid, enter in table.

• Subtract the overall FSC value from table 1 from GMT solid to obtain GMT fluid, enter in table.

Table 3 Calculating actual trim • To obtain the trim lever take the difference between LCB and LCG, enter in table. • To obtain an estimate of the actual trim multiply the displacement by the trim lever

and divide that sum by the MCTC. This provides the trim in cm units. • If the LCG is fwd of the LCB the vessel is trimmed bow down, and conversely if the

LCG is aft of the LCB the vessel is trimmed stern down. • The aft draught may be found by dividing the LCF value by the X (m) value shown

on the ‘Diagram to show Draught mark locations’ and multiplying that value by the trim, and adding or subtracting that value to or from the LCF draught value depending on the direction of trim. If the vessel is trimmed stern down, then add, otherwise subtract.

• The fwd draught may be found by dividing the LCF value by the Y (m) value shown on the ‘Diagram to show Draught mark locations’ and multiplying that value by the trim, and adding or subtracting that value to or from the LCF draught value depending on the direction of trim. If the vessel is trimmed stern down, then add, otherwise subtract.

• Using the newly calculated values for fwd and aft draughts calculate the revised estimate of the trim. Compare this revised trim value to the original estimate of trim in table 2. Iterate to convergence.

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Freeboard Load line Mark In accordance with the load line regulation the following Plimsoll mark is to be attached to the vessel.

Top of Deck at side

Assigned

summer freeboard

25mm

Summer

DraftUSK

underside of keel

300mm

450mm

25mm

Note: Load Line approving classification society’s initial may be inserted on Plimsol mark Loading Conditions Stability Form and stability criteria code assessment to be presented in the following conditions; • Lightship • Departure (100% consumables) • Half Load (50% consumables) (OPTIONAL CONDITION) • Arrival (10% consumables)

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Hydrostatics Tabular output showing Displacement, Draught, LCG, VCB, KMT, KML, TPC and MCTC across the range of operational draughts and trims. Suggested at Trims of –0.2m, -0.1m, 0m, 0.1m & 0.2m NOTE: Water Density =1.025 T/m3 K is to underside of keel at amidships Draught is to underside of keel at amidships Cross Curve Stability Plot Tabular Output showing KN curve values across the range of operational displacements and trims. Suggested at Trims of –0.2m, -0.1m, 0m, 0.1m & 0.2m NOTE: Water Density =1.025 T/m3 VCG = zero m Minor Modifications Date Item Mass VCG VCG Mmt LCG LCG Mmt