Inclining Experiment 1

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Inclining Experiment

Inclining Experiment 2

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Learning Objective

After studying this chapter, the student should be able to:

1. Assist in carrying out an Inclining Experiment.

2. Derive a ship’s lightship KG, or the KG in a known load condition, using the results from the Inclining Experiment

Inclining Experiment 3

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Why carry out an inclining experiment?

To determine in an accurately known condition a ship’s:

1. KG

2. Displacement

Inclining Experiment 4

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When should an Inclining Experiment be carried out?

1. For a new ship as nearly complete as possible (i.e., lightship).

2. When major structural / machinery modifications have been carried out.

3. When ascertainment of a ship’s KG is desirable, or when requested by Classification Society or Port of Registry.

Inclining Experiment 5

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Preparation for the Experiment

• Inspection

– All tanks should be inspected to ensure that they are empty

– If it is not possible to empty the tanks, they should be topped up to ensure that there would be no free surface effect during the experiment

– Oil in crankcases and hydraulic oil systems are acceptable, but the levels in oil reservoirs should be carefully controlled.

Inclining Experiment 6

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Preparation for the Experiment

• Inspection

– The bilge should be dry as should all ballast spaces.

– The vessel should be on an even keel. If it is not, weights can be added and their position recorded both horizontally and vertically (and of course, the actual weight recorded).

Inclining Experiment 7

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Preparation for the Experiment

• Mooring

– the weather must be good, sea flat calm and no wind

– light mooring lines should be used

– ensure that moorings are not so tight that they restrict vessel movement

– the vessel must be well clear of the quay and should not be in danger of touching the bottom during the experiment

Inclining Experiment 8

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Preparation for the Experiment

• Measurement of Freeboard/Draft

– The measurement of the freeboard is most important

– The measurements should be made from a small boat or skiff and without touching the vessel in a way that would cause it to roll or pitch

– Anyone on board should stay on the centre line and not move about

Base line

Water line

Inclining Experiment 9

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Preparation for the Experiment

• Movable object secured

• Only required personnel onboard

• Ship should preferably be initially upright

Inclining Experiment 10

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Pendulum arrangement

• If it is not possible to have more than one pendulum due to the size of the vessel, it should be located as close to amidships as possible and on the centerline.

Inclining Experiment 11

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Pendulum arrangement

• The pendulum should not be too short otherwise it would be difficult to accurately measure the deflection. Even in a small vessel it should not be less than 2 metres in length, but the longer, the better. The intention is to get a reasonable measurement at small angles of heel (not less than 2° and not more than 4°.

• The weight at the end of the pendulum should lie within a damping liquid.

Inclining Experiment 12

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Provision of Weights

A B C D

Experiment 0

Inclining Experiment 13

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The Experiment

AB

C D

Experiment 1

BA

CD

Experiment 2

Inclining Experiment 14

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The Experiment

C

A B

D

Experiment 4

A B

C D

Experiment 5

Inclining Experiment 15

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Calculations

Note that KM is constant for a particular draft and can be obtained from the

vessel’s curves of form.