Cutty Sark: Difference between revisions

''Cutty Sark'' has a registered length of {{convert|212.5|ft|m|2}}, with a depth of hold of {{convert|21|ft|m|2}} and a net tonnage of 921. The hull is one of the sharpest of all the tea clippers: she has a coefficient of under deck tonnage{{efn|The coefficient of under deck tonnage is a method of estimating the "sharpness" of a hull design when all the necessary dimensions of the ships being compared are not available. Sharpness is the amount by which a hull differs from a rectangular block of the same length, breadth and depth: the more material that has to be cut away from that notional block, the sharper the hull. For the coefficient of under deck tonnage, the [[block coefficient]] and the [[prismatic coefficient]], the lower the number, the sharper the hull.}} of 0.55, compared to ''Thermopylae'' at 0.58.{{r|MacGregor 1983|pp=195–99, 247}} ''Cutty Sark'''s [[prismatic coefficient]], another measure of hull sharpness, is 0.628; this allows comparison with US built clippers studied by [[Howard I. Chapelle]].{{efn|The prismatic coefficient for clippers studied by Chapelle can be seen in his book The Search for Speed Under Sail. The prismatic coefficient for some of the more famous US built ships are:<br/>''Challenge'' (1851) 0.60 the most extreme clipper by builder [[William H. Webb]]<br/>''[[Witch of the Wave]]'' (1851) 0.66 an ordinary clipper but with speed records from China to London<br/>[[Lightning (clipper)|''Lightning'' (1854)]] 0.61 An extreme clipper built by [[Donald McKay]] - an example of the larger sized US-built clippers<ref name="Chapelle 1967">{{cite book |last1=Chapelle |first1=Howard I. |author1-link=Howard I. Chapelle |title=The Search for Speed Under Sail, 1700–1855 |date=1967 |publisher=Bonanza Books}}</ref><br/>It is probable that few, if any, merchant sailing vessels had a prismatic coefficient of less than 0.57.{{r|Chapelle 1967|p=45}}}}{{efn|An alternative prismatic coefficient calculation for ''Cutty Sark'' is given as 0.627 based on a survey of the ship afloat in 1937.{{r|Scott 1941|p=185}}}} After water-line length, the prismatic coefficient is the next most important determinant of potential hull speed.<ref name="Cannon 2021">{{cite journal |last1=Cannon |first1=Sophie |last2=Boyd |first2=Stephen |last3=Whitewright |first3=Julian |title=Development of a Quantitative Method for the Assessment of Historic Ship Performance |journal=Practical Design of Ships and Other Floating Structures |series=Lecture Notes in Civil Engineering |date=2021 |volume=63 |pages=269–89 |doi=10.1007/978-981-15-4624-2_16|isbn=978-981-15-4623-5 |s2cid=225128699 }}</ref> Unladen, or with a cargo of low density, ballast was required for stability. For example, when she was loaded with wool, 200 tons of ballast was carried. The largest wool cargo she ever carried was 900 tons weight (the total of ballast and cargo of 1,100 tons is consistent with the estimated deadweight cargo capacity of 1,135 tons at 20&nbsp;ft draught). The largest tea cargo carried was 615 tons weight. Conversely, a dense cargo allowed full use of the deadweight capacity: if loaded with coal, she would usually carry 1,100 tons.{{r|Scott 1941|p=187}}