. Science of the sea. An elementary handbook of practical oceanography for travellers, sailors, and yachtsmen. an * It may be mentioned here that Challenger, usedhemp ropes of 2 inches and 2\ inches circumference, withbreaking-strains of 1 ton 12 hundredweight and 2 tons 6 hun-dredweight respectively. For shallow-water work was em-ployed a rope of 3 inches circumference, with breaking-strainof 2 tons 11 hundredweight. But it must be remembered thatin water a hemp rope carries much more of its own weightthan a steel rope. Sir John Murray informs us that the ropewas hauled at the rate of
. Science of the sea. An elementary handbook of practical oceanography for travellers, sailors, and yachtsmen. an * It may be mentioned here that Challenger, usedhemp ropes of 2 inches and 2\ inches circumference, withbreaking-strains of 1 ton 12 hundredweight and 2 tons 6 hun-dredweight respectively. For shallow-water work was em-ployed a rope of 3 inches circumference, with breaking-strainof 2 tons 11 hundredweight. But it must be remembered thatin water a hemp rope carries much more of its own weightthan a steel rope. Sir John Murray informs us that the ropewas hauled at the rate of 1,000 fathoms per hour, and thatduring the three and a half years cruise, when trawlings anddredgings were made at 354 stations, there were only elevencases of parting of the rope. Wire ropes were first used forsuch work by Agassiz in 1877. WIRE ROPE 273 expedition rather than a yachting cruise, but forwork to 2,500 fathoms the following combination maybe suggested : 1,500 fathoms of i-inch rope at thetrawl end, 1,000 fathoms of ij-inch, and 500 fathomsof ij-inch at the winch end, all shackled together ;*. Fig. 194.—Section of Wire Rope. (By Permission ofMessrs. Bullivant.) a special shackle is made for this work. The objectof this combination is to strengthen the rope where theheaviest strain comes, and the total result is as follows,taking ropes d, e,foi the list on p. 272 as types : Weight. Breaking -Strain. ton. cwt. tons. cwt. At sheave I 17 8 O Above first shackle I 7 8 O Below „ I 7 4 14 Above second shackle .. O 13 4 M Below O 13 3 II Whether the rope be stored on the winch-barrel oron a separate reel, it should be carefully and evenlyspread as it comes in. In hauling heavy gear, especi-ally where the warp is wound directly under consider- * Owing to the shackles (or splices) such a rope could not beused below 1,500 fathoms for closing-nets or similar apparatusworked by messengers. iS 274 YACHT EQUIPMENT able tension, the spreading is best done by means of amechanic
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectocean, bookyear1912
