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Paragraf Tamamlama 12. Soru

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12.

Lightships are aids to navigation, similar in function to lighthouses. They came into use in the 17th century in places where it was not practical to build a lighthouse. Modern lightships are steel vessels about 35 metres long ………… . Some lightships, however, those equipped with automatic devices, require no full time crew on board.

They are most suitable for sheltered waters where high-powered illumination is not necessary

Usually they are manned by a crew of about seven, and carry all the equipment standard to a lighthouse

Because lightships are often located in remote places, the power used to operate them is usually derived from diesel generators

To increase light intensity and focus it into a beam, mirrors and other reflectors came into use in the 18th century

Modern lighthouses have reflectors, as well as lenses and prisms, to carry the light farther