GLASGOW COLLEGE OF NAUTICAL STUDIES

SHIP STABILITY 1

D78A 34

TUTORIAL 4: Load line calculations

1.                  A ship with a statutory summer freeboard 1702 mm, FWA 165 mm has a spacing of 152 mm between the summer and winter load lines. The top edge of the line through the starboard disc is 26 mm below the water surface; the top edge of the line through the port disc is 100 mm above the water, and the ship is in water RD 1.005. TPC is 18. Calculate the amount of cargo to load for a Winter zone voyage

(30.0 t)

2.                  A ship with FWA 22 cm and TPC 15 is loading in dock water RD 1.013. The upper edge of the line through the centre of the disc is level with the water on the port side and 8 cm clear of the water on the starboard side. If 125 t of fuel and 55 t of fresh water is still to be loaded, calculate the cargo which can be loaded to put the ship to the summer marks in salt water.

(35.8 t)

3.                  A ship with length 196 m, breadth 30 m and depth 16.24 m to the freeboard deck has a loaded summer freeboard in SW of 4.84 m corresponding to a displacement of 56250 t. The water plane area coefficient is 0.92. The ship has a starboard list and the freeboards at present are 5.40 m to port and 4.92 m to starboard in dock water RD 1.018. Calculate the quantity to be loaded in order that the ship will be at the tropical salt water load line when in open sea after consumption of 82 t of oil and water on river passage.

(3543.2 t)

4.                  A ship has a loaded summer draught of 14.65 m corresponding to a freeboard of 4.90 m for which the displacement is 106240 t and TPC is 78. The draughts at present are F 13.46 m and  port side A 14.28 m and starboard side A 14.42 m in water RD 1.006. Calculate the quantity of cargo to load in order that the ship will be at the winter load line in salt water assuming the ship is neither hogged nor sagged and that 840 t of fuel and stores have yet to be taken on board.

(4511.1 t)

5.                  A ship is floating in dock water RD 1.006. The waterline to port is 12 cm below the lower edge of the ‘S’ mark and on the starboard side is 4 cm above the upper edge of the ‘W’ mark. If the summer displacement is 21620 t (corresponding to a draught in salt water of 6.86 m, TPC 18.6), how much cargo remains to be loaded to ensure that the ship sails at the ‘W’ mark in salt water.

(368.8 t)

6.                  Sketch the load line marks for a ship of length 110 m, summer draught 6.00 m corresponding to a summer displacement of 12000 t and WPA of 2100 m2. Indicate all dimensions, stating which are fixed and which are variable and show how you obtained the values of the variable dimensions.

7.                  The hydrostatic particulars for a ship give the following data for the Summer mark:

Displacement 35800 t

Draught 12.0 m

Freeboard 2400 mm

TPC 42

The ship is loading up river in dock water RD 1.012 and at a stage in loading the freeboards to port and starboard are 2600 mm and 2580 mm respectively. Calculate how much cargo to load so as to be at the tropical marks in salt water if 150 tonnes of fresh water have to be taken on board before sailing and 50 tonnes of fuel are to be consumed on passage down river to the sea.

                                                                                                                              (2184 t)

8.              Sketch a hydrometer suitable for use on board a ship and describe how and under what circumstances it should be used.

9.              A ship is loading in a dock up-river in water RD 1.004 and is required to proceed to an explosives anchorage at the mouth of the river in order to complete loading a further 450 t. The summer freeboard in SW is 4990 mm and the winter penalty is 190 mm. FWA is 180 mm and TPC for the loaded summer draught is 29. Calculate the freeboard which the ship must be at on leaving the dock berth, if it is to be at the winter load line on reaching the open sea, if it is anticipated that 60 tonnes of fuel will be consumed on passage from the berth to the sea.

                                                                                                                              (5166 mm)

10.             A small ship has a summer displacement of 6220 t, summer freeboard in SW of 1072 mm which corresponds to a summer draught of 5.808 m. When floating at the summer load line the waterline length and breadth are 95.0 m and 13.0 m respectively, Cw being 0.750.

(a)               If the ship has to load to the tropical marks in salt water find the draught to which it should be loaded in a port where the dock water RD is 1.008.                                                                                   

(6.04 m)

(b)              Sketch the load line marks for this ship as they would appear on the Port side indicating all variable and fixed dimensions showing all calculations as appropriate.

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TUTORIAL 4 – Load line calculations (MAR Rev. 21/11/03