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(SCV Code III/8)
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Page 1 of 8
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Name of
Vessel -----------------------------------
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Documentation No. -------------
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Date
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Owner/Representative -------------------------------------
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Inspector
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Location
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Wind:
Relative Direction -------------
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Vel --------kts
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Mooring
Arrangement
--------------------------------------------------------------------------------------------
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Route
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Check One
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Exposed ..
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Coastal
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Protected
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Indicate on above Sketch
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Indicate on above Sketch
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1)
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Profile of sheer line.
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1)
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Round or
vee bottom
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2)
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Length overall (L)
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2)
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Maximum
beam (B) to outside of shell; greater or equal to (Bf).
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3)
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Station for measuring Reference Freeboard (f) above load waterline
(LWL), located in way of least freeboard or at a point ¾ (L) from the stem if
the least freeboard is aft of this point.
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3)
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Maximum
beam (Bp) accessible to passengers.
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4)
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Maximum beam (Bf) on
deck in way of Reference Station.
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4)
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Freeboard at bow
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5)
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Reference Freeboard (f), height of sheer line above the LWL, in way
of Reference Station.
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5)
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Freeboard at stern*.
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6)
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Height of
weather deck (including cockpit deck, if any) above load waterline in way of
Reference Station.
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All of the
above measurements are to be taken in the loaded condition without list
(III/8.6). Measurements for (L), (B), and (Bf) are to exclude rub
rails. If the vessel carries passengers on diving excursions, the total weight
of the diving gear must be included in the loaded condition. If the vessel has
a cockpit or well deck, show same by dotted line on the above sketches and
indicate length (/).
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*Freeboard
shall be the distance from the sheer line to the load waterline. The sheer line
shall be taken as the intersection of the side shell with the weather deck.
Where calculations require “gunwale top” to be used, the following applied: For
a cockpit vessel, the gunwale top shall be measured along an imaginary
extension of the sheer line in way of the cockpit. For an open boat, the
gunwale top shall be considered the sheer line.
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Passengers
include the crew.
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Page 2 of
8
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(1) TOTAL TEST WEIGHT REQUIRED:
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----------------------------- X --------------------------- =
------------------------------------------
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# of Pax
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Wt/Pax
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Total Test WT. (W)
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Notes:
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a)
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“Test Weight” defines only the weight to be moved during the test.
Weights used to represent missing equipment or stores shall be considered part
of the “loaded condition.”
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b)
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The maximum
number of passengers shall not exceed the number computed in accordance with
SCV Code II/15.
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c)
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Weight per
passenger equals 75kg (166 lbs), except that on “protected waters” when
passenger loads consists of men, women and children; a weight per passenger of
65 kg (143 lbs) may be used.
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(2) DISTRIBUTION OF TEST WEIGHT:
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a)
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Distribute
the test weight fore and aft so as to obtain the normal operating trim.
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b)
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Arrange the
test weight so that its vertical center of gravity (CG) is approximately 76.2
cm (30 inches) above deck.
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c)
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The
vertical distribution of the test weight shall be such as to simulate the most
unfavourable vertical CG likely to occur in service. On vessels having one
upper deck above the main deck available to passengers, the vertical weight
distribution shall not be less severe than the following:
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Total test
weight (w) …………………………………………….. = -----------------------
Passenger capacity of upper deck:
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---------------------- X ----------------- X 1.33 =
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Weight on Upper
Deck
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# of Pax
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Wt/Pax
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----------------
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Weight on Main
Deck
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(3) WIND HEEL CALCULATION:
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a)
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With the
vessel in the loaded condition, block off the profile of the vessel into
rectangles using vertical lines starting at the load waterline, as shown below.
Include passenger railings, canopies and spotting towers.
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b)
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Measure, on
the vessel, the length (L) and height (V) of each rectangle and enter into the
table on Sheet 3.
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c)
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Complete the
calculations in the table, add the products in the last column and enter the
sum in Section (4) (b). Multiply this sum by the appropriate (P) value to
obtain the Wind Heeling Moment (Mw) in Section (4) (b) on page 3
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Value of
(P)
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k/m 2
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lb/ft 2
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Exposed
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73.2
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15.0
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Partially Protected
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48.8
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10.0
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Protected
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36.6
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7.5
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(continued on page 3 of 8)
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Page 3 of 8
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(3) continued
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- Profile -
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Load Waterline
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Scale: 1 square = -------------
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- Calculations -
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Section
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L
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V
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A (L x V
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H (
0.5V )
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A x H
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A
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B
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C
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D
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E
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F
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G
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Sum (A x H )
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____________
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(4) REQUIRED HEELING MOMENT:
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Apply (a) or (b), whichever is greater:
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(a) Passenger Heeling Moment (Mp) = (W X Bp)/6 =
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------------------------------------ X ---------------------------------)/6 =
---------------------------------
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Total Test
Wt. (W)
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Max Beam Open
to Passengers (Bp)
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(b) Wind Heeling Moment (Mw ) =
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------------------------------- X ---------------------------------
= ---------------------------------
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Wind Pressure
(P)
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Sum (A x H
)
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Page 4 of 8
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(5) LOCATION OF IMMERSION MARK (i) ABOVE LOAD WATERLINE PRIOR TO APPLICATION
OF HEELING MOMENT:
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The freeboard measurement (f) shall be taken with the weight
required in Step (1) on board. The height of the immersion mark (i) shall be
the lesser of the two values provided by (a), (b), (c) or (d) according to
vessel type, or (e) for all vessels. The mark (i) shall be placed on the hull
above the LWL at the reference station.
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i = ___________________
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(a)
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Flush Deck Type Sailing Vessels (or well deck vessels that operate on
protected waters, have non return scuppers, and the reference freeboard is not
more than one quarter of the distance from the waterline to the top of the
gunwale). Reference freeboard (f) is measured to the top of the
weather deck at the side of the vessel.
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___________________ = ________________________
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Reference freeboard
(f)
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Height of (i) above
LWL
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(b)
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Flush Deck Type Vessels (including all well deck vessels except
those noted in (a) above) For well deck vessels, freeboard (f) to the lowest
deck exposed to the weather must equal or exceed 25.4 cm (10 inches)
If less than 25.4 cm, use 5(d) Open-boat Type formula
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_____________________/2 = ______________________
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Reference
freeboard (f)
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Height of (i)
above LWL
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(c)
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Cockpit Type Vessels
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Exposed Waters
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Freeboard to cockpit deck must equal or exceed 25.4 cm (10 inches)
If less than 25.4 cm, use 5 (d) Open—boat Type formula
Length overall ……………………………………..(L) Length of
cockpit …………………………………..(/) Reference freeboard
………………………………...(f) (measured to top of gunwale) Height of
immersion mark above LWL ……………..(i) All measurements shall be
in metres (feet)
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(i) = f ( 2L – 1.5/ )
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__________
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4L
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Coastal or Protected Waters
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(i) = f (2L - / )
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_________
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4L
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(d)
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Open-boat Type Vessels
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Reference freeboard (f) is measured to top of gunwale
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___________________ /4 = ______________________
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Reference
freeboard (f)
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Height of (i)
above LWL
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(e)
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All Vessel Types
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To limit the final angle of list to 14° for any type of vessel, the height of
the immersion mark (i) shall on no case exceed the value below. If this value
is less than that produced by (a), (b), (c) or (d) above, whichever applicable,
then this value shall be used for (i).
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_________________________/8 =
_______________________
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Beam at Reference Station
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Max height of
(i) above LWL for any type of vessel
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Page 5 of
8
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(6) WEIGHT MOVEMENT:
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a)
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The heeling moment
required by Section (4) shall be obtained by a transverse movement of the test
weights.
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b)
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The test shall be
conducted with all tanks ¾ full, ballast aboard in place, all portlights
secured, and any non-return valves or flaps on scuppers or deck drains
restrained in the open position.
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c)
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The vessel shall be
fully afloat and all mooring are to be slack during the test.
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d)
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During the loading
and moving of test weights, care should be taken if there is evidence of low
stability. This may be assumed to be the case whenever the effect of any added
or shifted weight increment is noted to be more than that of the preceding
increment of the same size, or when the chine or bilge amidships comes out of
the water as a result of the heel.
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e)
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Care is to be
exercised that the vessel is not heeled excessively either due to weight
movement or superimposed roll which could cause the test weights to topple or
ship’s gear to become adrift.
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f)
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While the vessel is
heeled, check for open seams, loose hull fittings, etc., which are not normally
immersed and which could cause flooding of the vessel.
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Quality
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Weight per
Unit
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Distance
Moved
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Moment
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Total Heeling Moment
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Page 6 of 8
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(7) HEIGHT OF IMMERSION MARK (I) ABOVE WATERLINE AFTER WEIGHT MOVEMENT:
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i =
-------------------
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a)
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If the
vessel lists to the immersion mark (i) before the full heeling moment is
applied, the test shall be stopped and the vessel fails the test.
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b)
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When the
moment required in Section (4) has been developed, measure the resulting height
of the immersion mark (i) above the waterline.
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c)
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If any
portlights are found to be near the waterline at the final angle of the list,
such portlights on each side shall be permanently closed.
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d)
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If any
scuppers or drains are found to be below the waterline at the final angle of
list so as to permit entry of water into the or onto the deck, such openings on
each side shall be fitted with automatic non-return valves.
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(8) GENERAL STABILITY INFORMATION (for documentation purposes only)
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Tankage
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Tank
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Capacity
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Approximate Location of CG @ 100% Cap.
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Aft of
Stem
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Above Top of
Keel
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Ballast:
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Material
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Weight
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Approximate Location of CG
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Aft of Stem
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Above Top of
Keel
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Page 7
of 8
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TWENTY-FIVE PERCENT TEST
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(This test is not a necessary part of the Simplified Stability Test
Procedure but may be used as a preliminary Check when the
stability is believed to be marginal)
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1.
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After the Total Test Weight (W) has been placed on board and the Reference
Freeboard (f) has been measured, rig a pendulum free to swing athwartships at
any convenient location on the vessel. Arrange it so that the bob is
approximately 3 mm (1/8 inch) above the deck. Place a chalk mark on the deck
directly beneath the bob. Measure the pendulum length (pend. 1) as the distance
from pivot to deck.
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2.
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Move the test weight to obtain a heeling moment equal to one-quarter of the
Required Heeling Moment in Section (4) on page 3. It is suggested that the
weights having the longest levers be moved as to minimize the amount of weight
handled.
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One – quarter
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Heeling Moment:
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--------------------------- /4 = ---------------------------
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Req’d H.M.
(4)
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3.
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After the weight has been moved, place a chalk mark on the deck directly
beneath the pendulum bob. Measure the pendulum deflection (pend. D.) as the
distance between chalk marks.
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4.
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Before proceeding with the Simplified Stability Test Procedure, the following
calculations may be carried out to anticipate the results:
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Approximate Maximum allowable Heeling Moment:
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2 X
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X
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X
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¼ H.M
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pend. 1.
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Height of (i)
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= ----------------
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--------------------------------
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X
-------------------------------
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pend.d.
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Beam at Ref.
Station (Bf)
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If the Maximum Allowable Heeling Moment is LESS than the Required
Heeling Moment in Section (4) on page 3, the vessel will probably fail the test
by the difference indicated below.
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Required Heeling Moment
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= --------------------
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Allowance Heeling Moment
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= --------------------
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Difference
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=
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If Passenger Heel (4a) applies Approximate Number of
Passengers in Excess
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If Wind Heel (4b) applies: Approximate Excess Wind
Moment (Sum A x H )
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6 x ___________
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Difference
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___________
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----------------------------
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/
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=
-----------------------------
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# of Pax
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Difference
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( P
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Moment
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_________________ X
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__________________
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Wt/Pax
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(Bp)
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Page 8 of
8
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STABILITY TEST PROCEDURE FOR VESSELS CARRYING PASSENGERS AND CARGO
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(1)
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For vessels carrying cargo as well as passengers, follow the same test
procedure as for vessels carrying passengers alone except that, in addition to
the passenger test weight, the maximum deadweight of cargo permitted shall be
on board, in place and so arranged as to simulate the most unfavourable
vertical center of gravity likely to occur in service.
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(2)
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Specify the maximum cargo deadweight permitted to be
carried:
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Weight of Cargo
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Approximate Location of CG
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Aft of Stem
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Above Top of Keel
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(3)
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Complete the Twenty-Five Percent Test based on the Passenger Heeling Moment or
the Wind Heeling Moment, whichever is applicable, and note the anticipated test
results.
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(4)
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If the anticipated results of the test indicates that the vessel will fail,
the entire test must be repeated with a reduced number of passengers and/or a
reduced amount of cargo, or by utilizing any other corrective measures
available.
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(5)
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If the anticipated results of the test indicates that the vessel
will pass, then with the vessel in the heeled condition and being cautious not
to disturb any of the test weights which were shifted in order to heel the
vessel; remove approximately one-quarter of the cargo from the vessel
exercising great care to remove it symmetrically about the centerline.
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(a)
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If the pendulum deflection DECREASES or remains unchanged -- replace the cargo
which was removed and complete the stability test procedure.
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(b)
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If the pendulum deflection INCREASES
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-- the cargo may be improving the stability of the vessel.
Therefore, remove all of the cargo from the vessel, replace the test weights in
their original positions so as to remove all list, remeasure the Reference
Freeboard (f), and repeat the Twenty-Five Percent Test in its entirety for the
new condition of loading. If the second Twenty-Five Percent Test indicates that
the vessel will pass, complete the stability test procedure.
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(6)
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If the vessel passes the stability test procedure under these conditions, it
is deemed to have adequate stability for the safe carriage of passengers
allowed regardless of whether or not cargo, not in excess of the amount
specified in item (2) above, is carried.
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