A R BRINK & ASSOCIATES
MARINE CONSULTANTS & SURVEYORS
ARB House, 143 Maydon Road, Maydon Wharf, Durban, 4001
P.O. Box 29238, Maydon Wharf 4057, South Africa
Telephone (+27 31) 2061861, Fax (+27 31) 2061860
E-mail survey@arbrink.com web.site http://www.arbrink.com
DRAFT SURVEY FORMULAE
After Amidships Forward
Perpendicular Perpendicular Perpendicular
Summer
Freeboard Measured LCF
Freeboard S.W.L
Water line
Summer WL
Draft
Draft = (Summer Freeboard + Summer Draft) - Measured Freeboard Position of the after, amidships, and forward perpendiculars
CORRECTION TO THE PERPENDICULARS
Correction = Distance of draft x Trim read from draft marks
marks from End perpendicular Distance between draft marks
Correction = Distance of draft x Trim at perpendiculars
marks from Amidships line Length between Perpendiculars
CORRECTION FOR HULL DEFORMATION
Correction = Forward draft + After draft + (6 x Amidships draft)
8
Note:
Known as the 'Mean of Means draft' providing a more accurate mean draft when the ship is hogged or sagged.
CORRECTIONS FOR TRIM
FIRST TRIM CORRECTION (or 'Layer' correction):
Correction (tonnes) = Trim (cms) x LCF (metres) x TPC
LBP (metres)
Note:
Where LCF means distance of the LCF from Amidships and LBP is the length between perpendiculars. To apply this
correction, when the LCF is in the same direction from amidships as the deepest draft it is added to the displacement
and when it is in the opposite direction it is subtracted.
SECOND TRIM CORRECTION:
Correction (tonnes) = (Trim in metres)² x 50 x dM
LBP (metres) dZ
Note:
Where dM
dZ
is the difference between the MCT for a draft of 50 cm greater than the corrected mean draft and 50 cm less than the
corrected mean draft. This correction is always added to the displacement.
CORRECTION FOR HEEL
Correction (tonnes) = 6 x (T1 - T2 ) x (D1 - D2)
Note:
Where T1 is the TPC for the deepest draft amidships (D1) measured in metres and T2 is the TPC for the shallower draft
amidships (D2) measured in metres. The correction is always added to the displacement because the effect of heel is to
increase the waterplane area and so lift the ship out of the water.
CORRECTION OF DISPLACEMENT FOR DENSITY
True Displacement = Scale displacement x Density of dock water
Density used for the displacement scale
SOURCE: NAUTICAL INSTITUTE
DRAFT SURVEY CALCULATION FORMAT
SHIP: Flag: Date:
Deadweight: Commodity: Time:
Summer Draft: Survey: Initial / Final Hatches:
Weather Conditions (Wind / Swell):
LDM = dF = dMs = DA =
Drafts Forward Midship Aft
Port
Starboard
Mean
Correction
Corrected Draft
Draft Fore Apparent Trim
Draft Aft
Fore and Aft Mean Mean of Means
Mean of Mean of Means
Draft correction for Hull deformation: Forward draft + Aft draft + (6 x Amidships draft) div. by 8
Trim Corrections
Displacement
100 x Trim x L.C.F. x T.P.C.
X
L.B.P.
Trim = Displacement for draft
L.C.F. = Total Trim Correction
T.P.C. = Corrected Displacement
Density Correction
L.B.P. =
Gross Displacement
50 x Trim² x Diff (MCT) (Always +)
L.B.P. Deductions
MCT 2 = Nett Displacement
MCT 1 =
Diff. =
Trim² =
Deductions
Ballast
Shore figure
Fresh Water
Fuel Oil Difference MT %
Diesel Oil
Lube Oil
REMARKS:
Total
Light Ship
Declared Constant
Protea Printers
