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Showing results for tags 'Mast length'.
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While researching the mast lengths for my HMB Endeavour build I came across an online copy of David Steel's The Elements and Practice of Rigging and Seamanship 1794. Here is the link: http://www.hnsa.org/resources/manuals-documents/age-of-sail/the-elements-and-practice-of-rigging-and-seamanship/page-1/ I am finding this to be a great resource even though it is a later compilation from different sources (there are other formulas which varied between shipyard and country during that time) because it has helped answered the tough questions I was having regarding the mast lengths and their respective heights above deck and outboard, which are important to know for the model builder. But to work this out I first needed to know where each mast is stepped. Currently no plan has been found showing the mast steps and below deck stanchion bracings. I finally found the answer in the opening chapter of David Steel's Mast Making Vol.1 which clearly indicates that the fore and main mast's are stepped on the keelson while the mizzen mast is stepped (or more correctly can be) on the lower deck. From this discussion we have located other sources which independently support stepping mizzen masts in the lower deck. The stepping of mizzen standing masts in the lower deck is also supported in William Mountaine 1761 'The Seaman's Vada-mecum and defensive war by sea', and other NMM ship plans prior the 1764 construction of Bark Endeavour. Working back from the 1771 Woolwich Yard mast measurements I found one set of Steel's formula to give me a very close match to these measurements as there are several formulas to choose from but only one set that appears to fit. Remembering that in 1764 ship building was still an evolving art which varied between country's and ship yards while Steel's work didn't come out until 1794, 30 years later. Given this time lag I think it is reasonable for there to be some lee way in interpretation and use of these formulas. With this in mind here is my math: Main Mast (whole length): Wooldwich Yard 69',4". Formula: L = Length, B = Breadth, L+B/2 To get this to work I've assumed L to be the measurement from stem to stern instead of the gun deck which Steel uses. The gun deck could could have become the standard in 1794 but might not have been in 1764. L @ 109' (approx) + B @ 29',2" divided by 2 = 69' (very close to Woolwich @ 69',4"). Stepped on the keelson @ 20',6" below the quarterdeck. 69',4" - 20',6" = 48',8" height above quarterdeck partners. Foremast: 8/9 of mainmast = 61',6". Woolwich Yard 65',4". Woolwich measurements are in yards @ 21yards, 28inches which would bring the foremast to almost the same height above the waterline as the mainmast and giving it a height of 47',4" above it's partners on the forecastle. (I have since revised this and the foremast looks to be close to within normal ranges at 65'4" compared to the main mast making it's cap around 2.5 feet below that of the main mast cap). Mizzen mast: 3/4 of mainmast = 51',11". Woolwich Yard 50',5". Stepped in the lower deck @ 12',6" below the quarterdeck gives a height of 38' above it's quarterdeck partners making it's cap around 8' below the main mast cap (within so called 'normal ranges') Bowsprit: (whole length) 3/7 of mainmast = 29',8". Woolwich Yard 34'. This does not match until we work out the outboard length which is 3/4 of 29',8" = 22',4". Considering where the bowsprit is stepped in the fore topsail sheet bits then @ 34' it achieves this outboard length of 22',4". The contemporary evidence critically examined in this discussion reasonably and logically supports that the 1771 Woolwich Yard measurements are accurate to within reason. The critical missing peace of the puzzle was that the mizzen might have been stepped in the lower deck and not the keelson as suggest by some late 20th century research. I almost missed this myself until I later searched for it as I realized with out this information I couldn't make sense of the Woolwich yard measurements because stepping the mizzen on the keelson at that length just wasn't meeting up with the angle of the mizzen chainplates from the as fitted draught of 1768. And would make the Mizzen cap 18' feet lower than the Main cap which just isn't the case in contemporary drawings and paintings attributed to Sydney Parkinson from Cook's voyage and nor is it within a so called 'normal range'. Where as stepping the 50'5" Mizzen in the lower deck brings it's cap up by 10' to within this normal range. I apologize for any inaccuracies.
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- HMB Endeavour mast lengths
- above deck mast heights
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