Mast materials and Specifications

  • 28 Feb 2017 13:07
    Reply # 4639155 on 1306051

    Many thanks both.  Some food for thought.  

  • 27 Feb 2017 23:09
    Reply # 4638113 on 1306051

    Jonathan, I concur that determining whether you have a conduit is a good idea.

    If you have conduit, the foam won't make it harder to pull wires through the conduit; no problems are created.

    If you foam the mast with bare wires, you will find that pulling new wires in should you ever need to add something or replace something will be very difficult, or nearly impossible. (I dealt with something like that once, and hope to never again!)

  • 27 Feb 2017 22:40
    Reply # 4638091 on 1306051

    Jonathan,

    Maybe the best first step is to establish whether you have a conduit, or just loose wires. This might be difficult to achieve though, so I would assume a fairly stiff conduit and go with a single hole, halfway up, for a start. If that solves the problem, then it's also the finish. If it doesn't, showing that the conduit is flexible or non-existent, then drill two more holes at the quarter and three quarter height points. I doubt whether more than that will be required. These three holes will be OK. Tystie's mainmast conduit was riveted in by Atlantic Spars, with pairs of rivets every two metres; that's a clever trick that I wouldn't advise anyone to attempt without seeing at first hand how it's done, but it seems to have done no harm (except that the rivet tails snag new cables as they are pulled through).

  • 27 Feb 2017 22:29
    Reply # 4638083 on 1306051
    David Tyler wrote:

    The conduit itself needs securing, or it will bang about. This is something that I omitted to do before stepping the mast. Now I will have to go halfway up the mast, drill a 5mm hole, spray in a mist of water and then insert the straw of an aerosol of polyurethane foam (water is what cures a one-part polyurethane). Polyurethane is long lasting and will adhere to almost anything. A good big plug of polyurethane foam should fix that pesky conduit.

    Jonathan Snodgrass wrote:

    Thank you for that David.

    The cables and/or conduits inside the aluminium alloy masts on Lexia make a frightful noise.  I have been wondering for some time on how to tackle that.  

    The prospect of having to lift two large masts to rework the innards does not bear thinking about.  

    I had therefore been pondering whether one could drill a hole in the cap on the mast and pour down small balls, presumably something like polystyrene pellets to fill up the mast.  (If the cap was big enough and one made a big enough hole then maybe table tennis balls !)  The repair the hole in the top of the cap.  I would guess that weight and moisture would not be issues.  

    However, maybe you have provided me with a more viable alternative.  

    I suspect that I would have to inject the foam in more than one place.  However, perhaps I should start with one injection in each mast and see if it stops the noise or not.  If it only reduced it the noise one might then be able to presume that one was on the right lines.  

    Would you have any reservations on a me putting a number of 5mm holes?  It might be sensible to stagger them round the circumference rather than in a straight line.  

    Does a 5mm hole cause any significant weakness?  I would guess not but would be open to advice from anyone.  I presume that one should try not to make  holes near the deck partners.  I was at one time advised that if after drilling a small hole one filled it with a monel rivet then it was as strong or stronger than before it was drilled.   

    All suggestions welcome.



  • 03 Aug 2016 10:50
    Reply # 4170574 on 1306051

    MAST FOR BEFUR

    Thank you to all the advice from members - Just FYI I today ordered the mast for Befur from ALC in Port Talbot in South Wales. Very helpful people.

    177mm diameter at base, tapering to 90mm at head with parallel sections at foot and head from 4mm extruded alloy. Weight 31kg, O/L length 6.4meters cost ~£480 (inc VAT) - I am collecting it to save transport costs....

    :-)

  • 03 Apr 2014 12:30
    Reply # 1530548 on 1306051
    One thing to note about these masts is that they are laminated with epoxy, not polyester. When I was researching this idea I used US wind loading ratings for comparison, the manufacturers all publish those. Those standards aren't relevant to sailors but are useful for comparison. The Whatley poles seemed far superior in weight, stiffness and ultimate strength, and they are the only ones I'm aware of that are made with epoxy resin, which may be at least part of the reason they are more rigid.
    Last modified: 03 Apr 2014 12:37 | Anonymous member
  • 03 Apr 2014 08:00
    Reply # 1530450 on 1306051
    I have never heard of anyone else using my method but it seems to work. In my masts I fixed the top of the conduit to the masthead, then compressed and twisted the conduit so that it was pressed against the outside wall of the mast in a spiral, then fixed it at the base. After two years of use no slapping or rattling of the conduits or wires, no additional weight either.
  • 02 Apr 2014 17:47
    Reply # 1530009 on 1306051
    [Sako started a new topic for this. Moved it here and inserted links. Brian.]

    Reading Robert Leaks post about his new fibreglass masts I remembered my brother used the work for a fibreglass flagpole factory just 25 km's (less in miles) from where I live. Sadly the factory is bankrupt, but the Swedish mother company still exports to Europe www.formenta.se

    Here is a video showing the strength of their glassfibre mast:

    http://www.youtube.com/watch?v=l8zHEjO_h04
    Last modified: 02 Apr 2014 17:47 | Anonymous member
  • 02 Apr 2014 14:05
    Reply # 1529839 on 1306051
    A quick Google turned up Silver Foil Bubble Wrap Insulation. Cheap and easy to find. Pure aluminium backing. Stick it on with expanding foam so it can't slip down the conduit. Problem solved.
    Another thought: I want a wire entenna for HF inside the main. Foil might cause funny things to happen to the RF signal, so use non-alloy bubble wrap in the main. Attach the antenna to the conduit with the cable ties. 2 problems solved.
     


    Last modified: 02 Apr 2014 14:12 | Anonymous member
  • 02 Apr 2014 13:32
    Reply # 1529825 on 1306051
    Deleted user
    Big nylon cable ties, put 3 together in a circle (120 degrees) and cut them slightly longer then halve the mast diameter. Repeat this every meter or so.
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