Draught survey calculation sequence with explanation of steps
Sometimes it is very important to get clear and correct reminder of draught survey calculations. Here is one of them:
| ARRIVAL | DEPARTURE | LINE | |||||
| DATE & TIME | * 1 | ||||||
| FORD | AFT | MID | FORD | AFT | MID | ||
| OBSERVED DRAFT : PORT | 12.54 | 12.54 | 12.57 | * 2 | |||
| STBD | 12.37 | 12.35 | 12.29 | * 3 | |||
| MEAN | 12.455 | 12.445 | 12.43 | 4 | |||
| APPARENT TRIM | -0.01 | 5 | |||||
| DISTANCE FROM PERPENDICULARS | -11.558 | 12.90 | + 6 | ||||
| LENGTH BETWEEN MARKS | 191.54 | 7 | |||||
| DRAFT MARK CORRECTION | 0.001 | -0.001 | 0 | 8 | |||
| TRUE DRAFT | 12.456 | 12.444 | 12.43 | 9 | |||
| TRUE TRIM | -0.012 | 10 | |||||
| TRUE MEAN DRAFT (TMD) | 12.45 | 11 | |||||
| OBSERVED DENSITY | 1.0155 | *12 | |||||
| SCALE DENSITY | 1.025 | +13 | |||||
| T.P.C. AT MID PORT | 64.57 | +14 | |||||
| T.P.C. AT MID STBD | 64.37 | +15 | |||||
| T.P.C. AT TRUE MEAN DRAFT | 64.475 | +16 | |||||
| L.C.F. | 0.605 | +17 | |||||
| L.B.P. | 216 | +18 | |||||
| M.T.C.@ T.M.D. + 50 cm | 989.31 | +19 | |||||
| M.T.C. @ T.M.D. - 50 cm | 958.49 | +20 | |||||
| DISPLACEMENT @ T.M.D. | 73908.5 | +21 | |||||
| 1ST TRIM CORRECTION | -0.217 | 22 | |||||
| 2ND TRIM CORRECTION | 0.001 | 23 | |||||
| LIST CORRECTION | - | 24 | |||||
| DISPLACEMENT AT EVEN KEEL | 73908.28 | 25 | |||||
| TRUE DISPLACEMENT | 73255.22 | 26 | |||||
| BALLAST | 196 | *27 | |||||
| FUEL OIL | 1562 | *28 | |||||
| DIESEL OIL | 86.7 | *29 | |||||
| LUB OIL | - | *30 | |||||
| FRESH WATER | 266 | *31 | |||||
| STORES | 0 | *32 | |||||
| MISC (const) | 230 | *33 | |||||
| MISC (light ship) | 9558 | *34 | |||||
| TOTAL DEDUCTABLES | 2110.7 | 35 | |||||
| NET DISPLACEMENT | 71177.52 | 36 | |||||
| CARGO LOADED/DISCHARGED | 61356 | 37 | |||||
EXPLANATION OF LINES:- * = OBTAINED BY OBSERVATION + = OBTAINED FROM SHIPS APPROVED STABILITY AND CALIBRATION TABLES ALL OTHERS OBTAINED BY CALCULATION AS FOLLOWS.
L4 = L2 + L3 L5 = L4 (aft) - L4 (ford) {STERN TRIM IS POSITIVE} L6 IF NOT IN SHIPS TABLES CAN BE ESTIMATED BY OBS
2 NAMED NEGATIVE IF PERPENDICULAR IS FORD OF MARKS
L7 = L18 + L6 (aft) - L6 (ford) { REMEMBER THAT A NEGATIVE MULTIPLIED BY A NEGATIVE RESULTS IN A POSITIVE }
L8 = L5 x L6 L9 = L4 + L8 L10 = L9 (aft) - L9 (ford) L11 = (6 x L9 mid ) + (L9 aft) + (L9 ford)
L7 8
L17 LCF IS USUALLY MEASURED FROM MIDSHIPS. IT IS USUAL TO NAME LCF AS NEGATIVE IF IT IS FORD OF MIDSHIPS, ON SOME SHIPS THE DATA IS LISTED WITH POSITIVE MEANING FORD OF AMIDSHIPS. THE OFFICER SHOULD ENSURE HE IS FAMILIAR WITH THE SYSTEM. IF IT IS GIVEN FROM THE AFT PERP THEN APPLY LBP/2
L22 = L16 x L17 X L10 x 100 L23 = (L19 » L20) x L10 x L10 x 50 (CORRECTION IS ALWAYS + ) L24 = (L9port » L9 stbd) x (L14 » L15) x 6
L18 L18
L25 = L21 + L22 + L23 + L24 L26 = L25 x L12 L35 = L27+L28+L29+L30+L31+L32+L33+L34 L36 = L26 - L35 L37 = L36arr » L36 dep