Screw propeller hoisting on an auxiliary steamer 1854.

Home Forums Nautical Research: 1830 – Present Day Screw propeller hoisting on an auxiliary steamer 1854.

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  • #24963
    William Lindsay
    Participant

      The SS Robert Lowe was launched on the Clyde in August 1854. It was described in the Greenock Advertiser as ‘the first auxiliary screw ship of large size ever built.’ It continued ‘The screw [propeller] can easily be unfastened from its place and hoisted by means of guides and a winch on deck, to a trunk or square recess in the ship’s counter, where it will be completely out of the water and offer no resistance to the vessel’s progress. When its assistance is required, it can be easily lowered into its proper position.’ Any ideas as to how this was exactly done? Do any plans exist?

      #24964
      Stephen B. G
      Participant

        FYI, I know that this does not answer your query, but it’s related to the topic. The U.S. Coast Guard Barque Eagle, former Horst Wessel of the Kriegsmarine built in 1936, employs a clutch of sorts that disengages the propeller so it freewheels when the vessel is under sail. I am not sure when this mechanical feature was introduced to sailing vessels with auxiliary engines, but it solves the same problem of the drag produced by the propeller when not in use.

        #24966
        Alistair Roach
        Participant

          Dear William,

          The following links may be of assistance to you –

          Blog and plans for building a model of HMS Terror with lifting propeller – http://buildingterror.blogspot.com/2013/09/

          Model showing lifting propeller at NMM – http://www.rmg.co.uk/collections/objects/rmgc-object-68183

          Model showing lifting propeller mechanism at Rijkmuseum – https://www.rijksmuseum.nl/en/collection/NG-MC-562

          Alistair

          #24968
          William Lindsay
          Participant

            Thanks Stephen – it all adds to the knowledge 🙂

            #24969
            William Lindsay
            Participant

              Many thanks Alistair

              I found further information on the SS Robert Lowe:
              Among other improvements introduced on board this vessel is the first mechanical apparatus ever made for lifting a three-bladed propeller and shipping it into the trunk hollow made in the counter for its reception.
              By the plan adopted, the propeller is disconnected from the shaft and hoisted alone, while in other vessels shaft and screw are lifted together.
              The hoisting apparatus consists of a block and tackle attached to the spanker boom (which is supported on massive crutches during the operation) and worked [by a] small iron capstan on the poop.
              Greenock Advertiser, 26/09/1854

              Notice the use of the spanker boom, which would indicate that the hoisting was done externally rather than internally. Although the description is useful, I’m still rather unsure exactly how it was done.hat was done. Bill

              #24974
              Frank Scott
              Participant

                Stephen B.G.’s answer about disengaging the propellor to allow it to freewheel is misleading.
                There is controversy about whether to lock shafts under sail, or leave them free to turn, with some people failing to appreciate that a free turning propeller is far from drag free. This is rather akin to helicopters, where a major safety factor is the ability to safely control the rate of descent after an engine failure by ‘auto-rotating’. There may seem to be little difference between the two choices apart from the wear and noise, but the principal drag criterion appears to be how much sailing energy is dissipated in turning the propeller, and the associated shaft, etc. Generally those that lock tend to do so on the intuitive grounds that a system should either be providing drive (as designed), or properly secured. Moreover, most marine gearboxes rely on an engine-driven pump for lubrication, and need to be modified before trailing, or have a ‘sailing’ clutch fitted to allow the shaft to rotate separately. Some vessels in an effort to be more green (and save money) now exploit the drag and drive from a turning propellor to generate electricity.
                Variable pitch propellors, where the blades can be set for minimal resistance with the shaft locked, avoid such issues, but are more expensive and complex.
                Worth also noting that the screw aperture for a single screw has an adverse effect on performance under sail, because the unavoidable cross-flow causes turbulence over the rudder, greatly reducing its effectiveness. This is a serious issue that became apparent from the first day that a sailing vessel had a screw fitted, and it is one reason why the rudders on modern sailing vessels with auxiliary engines are so much larger than was the case in pure sailing ships. ‘Boundary fences’ may prove useful in stabilising the flow over the rudder, and thus reducing weather helm at low speed.

                #25044
                William Lindsay
                Participant

                  Many thanks for your useful reply Frank. Much appreciated. Bill

                  #25045
                  Jeffrey A
                  Participant

                    Note that in autorotation for a helicopter, the pilot changes the pitch of the blade when nearing the ground, using the momentum of the rotating blades to generate lift. That’s not the same as a freewheeling propeller

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