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Posts : 88 Join date : 2011-07-12
| Subject: Initially the hulls Wed Jul 13, 2011 9:29 am | |
| Initially the hulls were constructed of wood, with lines like those of any other small merchant ship. This proved to be unsatisfactory for a ship that was permanently anchored, and the shape of the hull evolved to reduce rolling and pounding. As iron and steel were used in other ships, so were they used in lightvessels, and the advent of steam and diesel power led to self-propelled and electrically lighted designs. Earlier vessels had to be towed to and from station. Much of the rest of the ship was taken up by storage (for oil and the like) and crew accommodations. The primary duty of the crew was, of course, to maintain the light; but they also kept record of passing ships, observed the weather, and on occasion performed rescues. In the early 20th century, some lightships were fitted with warning bells, either mounted on the structure or lowered into the water, the purpose of which was to warn of danger in poor visibility and to permit crude estimation of the lightship relative to the approaching vessel. Tests conducted by Trinity House found that sound from a bell submerged some 18 feet (5.5 m) could be heard at a distance of 15 miles (24 km), with a practical range in operational conditions of 1–3 miles.[2][3] business opportunitydiseño pagina web | |
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