Aluminium pole masthead crane fabrication

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  • 25 May 2018 09:14
    Reply # 6260894 on 4001698
    Anonymous member (Administrator)

    All understood. Thank you again David.

  • 25 May 2018 07:08
    Reply # 6260808 on 4001698

    VHF antennae for masthead use are of the thin wire type, and are mounted on a piece of aluminium channel section extending out from the masthead so that interference with the light is minimal.

    However, you only need a masthead antenna for maximum range. A stern rail mounted antenna is fine for talking to harbour authorities and checking on other vessels' intentions, etc.

    It's helpful if some light will shine on a mechanical wind indicator. Electrical anemometers are usually mounted forward and below the masthead, because they don't need to be seen, but a Windex or similar goes on the aft side, with as thin a support as possible, and then interruption of the stern sector of the light is minimal.

    I have an Aquasignal tri-white LED  light, which is OK.

  • 24 May 2018 10:08
    Reply # 6258701 on 4001698
    Anonymous member (Administrator)

    Thanks Arne, I guess there are plenty of ways of making brackets, but the bit that I was wondering about was whether these extra pieces of equipment, such as wind vane and/or VHF aerial, placed alongside a tricolour masthead light would blank out a small sector of light from it.

    Maybe I am just imagining a problem there, I don’t know because this will be the first time I have a tricolour masthead light.

    I have never actually seen a picture of a masthead adorned with tricolour nav light, VHF aerial and wind vane all together. Maybe it is a silly question – but can they all fit together without partly masking one sector of the nav lights? – or is it just not an issue?


    Last modified: 24 May 2018 10:10 | Anonymous member (Administrator)
  • 24 May 2018 09:34
    Reply # 6257827 on 4001698
    Anonymous member (Administrator)

    Graeme

    Since most sailors have their own setup in their mast tops, I didn’t write in detail how the wind indicator should be attached. If it is attached to a 20-25cm tall stick above the mast, I bet the lee ribbon will start flying straight as well (the original plan), although I found the weather ribbon to give sufficient information to keep the right heading when fully close-hauled. That was the whole idea with it.

    In my case the wind indicator is attached with two stubs of 20mm tubes being butt-joined; splinted together with three strips of aluminium, held by hose-clamps. If I were to fit the top lantern I originally planned, I am sure I could make a combined bracket for the lantern and wind indicator.
    There is always a way. Even the second-best way is normally good enough.

    Arne


  • 24 May 2018 01:44
    Reply # 6257541 on 4001698
    Anonymous member (Administrator)

    I am planning a buttressed top plate welded to the aluminium tube, as described further back in this thread. I am wondering if there is a nice detail for the top plate, which would allow for masthead/nav light fitting, possibly VHF aerial - and also a tell tale (I rather like Arne's recent contribution).

    I am a bit puzzled though, if Arne has used his metal tube stub to carry the tell tale, how do the nav lights fit into the picture, or is Arne not using masthead light this time?

    (At the moment I don't have a masthead light fitting to look at - can anyone recommend a good one, that I can purchase?

    Mast light and tell tale is looking ahead a bit for me at the moment, but hoping to integrate it all now, while I am getting ready to have some welding done, might not be so easy later. Thanks, if anyone has a good detail they can share for this part of the mast top.

  • 01 Jun 2016 10:12
    Reply # 4050628 on 4041386
    Anonymous member (Administrator)
    Annie Hill wrote: I've always crossed the topping lifts in front of the mast and never had a problem with chafe on the mast lift from the topping lift.


    I've used the PJR way of fastening the topping lift, as described by Annie, on four boats now, and am about to fit the same setup to the fifth. The advantage with it is that i brings the topping lifts down a bit, which reduces the chances for the yard to fall farward of the topping lifts when the sail is dropped or reefed deeply. I have never seen any signs of chafe on the mast (painted or glassed wood)

    Arne

  • 01 Jun 2016 09:38
    Reply # 4050590 on 4001698

    I've now completed my masthead fitting. It consists of a length of 80mm diameter PVC bar, machined to fit into the top of the tapered alloy tube, and fixed in with Sikaflex. I've fixed on four 'blackodised' stainless steel eyeplates using over-sized M8 x 30 set bolts, as I found that it was difficult to tap a M6 thread into the PVC without the thread crumbling away. The eyeplates will be at +/- 45 degrees to the fore and aft axis; the after two are for the 2:1 main halyard, the forward two are for the lifts and an auxiliary halyard (burgee halyard, acting as a messenger for a mast-climbing rope). 

    I'm waiting for a Garhauer 25-13 block (currently stuck somewhere in UK Customs) to hang on the after starboard side eyeplate. Part of the thinking behind using PVC is that this stainless steel block will be knocking against plastic, rather than against the alloy tube. 

  • 26 May 2016 22:02
    Reply # 4041386 on 4041147
    David Tyler wrote: I think what's meant is that if the topping lifts cross in front of the mast, and the mast lift is on the port side, the port side topping lift and the mast lift will cross each other and will rub and chafe. If the port topping lift is attached at the port side, to the same point as the mast lift, there's no problem.


    I've always crossed the topping lifts in front of the mast and never had a problem with chafe on the mast lift from the topping lift.
  • 26 May 2016 19:50
    Reply # 4041147 on 4040907
    Phil Brown wrote:

    The 4 are set at 90 degrees and will be 45 degrees off of fore and aft . I uploaded photos to a newly made album but it doesn't show up on my profile page as I expected. The aft tangs are for the halyard. The forward ones are for lazyjacks to be joined forward of the mast. I planned to use the port tang to double for the mast lift. PJR seems to say that in that position it may be in the way of the lazyjacks but I can't visualize that. Would this work? If not any easy solution is to add and eyebolt from the top plate at 90 degrees.

    I think what's meant is that if the topping lifts cross in front of the mast, and the mast lift is on the port side, the port side topping lift and the mast lift will cross each other and will rub and chafe. If the port topping lift is attached at the port side, to the same point as the mast lift, there's no problem.


  • 26 May 2016 17:02
    Reply # 4040907 on 4001698
    Deleted user

    Got my aluminum masthead crane welded up yesterday to go on to the 3+ foot wood topmast of the hybrid mast. Had to add that when I went from a tabernacled to a keel stepped plan. The ¼ inch top plate overhangs the mast similar David's. The tube is only 1/8 inch so I wanted a larger welding surface that the overhang gave. It also allows me to option of hanging U bolts or welded closed eye bolts. I went with larger gussets/ tangs that I will drill like Arne's. The 4 are set at 90 degrees and will be 45 degrees off of fore and aft . I uploaded photos to a newly made album but it doesn't show up on my profile page as I expected. The aft tangs are for the halyard. The forward ones are for lazyjacks to be joined forward of the mast. I planned to use the port tang to double for the mast lift. PJR seems to say that in that position it may be in the way of the lazyjacks but I can't visualize that. Would this work? If not any easy solution is to add and eyebolt from the top plate at 90 degrees.

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