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Reusing aluminium tube masts

  • 18 Nov 2023 01:10
    Quote
    Reply # 13281016 on 13280500
    Anonymous member

    Graeme: Those extensions look good, and would be a great option to keep costs low. I hadn't thought of an extension in the lower end of the mast at all.

    Scott: The main mast (approximately 16cm / 6.3" diameter) has a wall thickness of 8mm / 5/16". The mizzen mast (approximately 14cm / 5.5") has a wall thickness of 6mm / 1/4".

    I will look up Arne's book. If they are on the small side, perhaps the main mast will be suitable as the new mizzen, maybe even with the old mizzen as the top extension, or some combination like that. After looking up the cost of hurricane-rated flagpoles, I am looking to reuse as much as possible!

    Best regards,

    Maxime
  • 17 Nov 2023 15:46
    Quote
    Reply # 13280775 on 13280500
    Anonymous member

    Hello Maxime,

    Do you know the thickness of the tube walls and what aluminum alloy was used to make the current spars? I suspect that these masts have stays for a reason, and they would not stand up to use as a freestanding mast on the same boat.

    Regardless I would suggest doing some calculations, as described by Arne in his TCPJR online book. Many people here have shared successful wooden extensions at the top of their masts. But, if the spar is not strong enough at the partners, it will not matter how well the extension is built.

    Scott.
  • 16 Nov 2023 23:20
    Quote
    Reply # 13280528 on 13280500
    Anonymous member (Administrator)

    It is not at all uncommon to add an extension to the top of a free-standing tube mast. I've done it with smaller diameter alloy tubing - but the best example in my opinion is Annie's hollow, birdmouth, tapered, timber topmast extension which she describes here.



    It is also possible to do a solid heel extension, but only right down by the heel, I personally would not like to see a transition anywhere near the deck partners.

    Last modified: 17 Nov 2023 03:02 | Anonymous member (Administrator)
  • 16 Nov 2023 22:25
    Quote
    Message # 13280500
    Anonymous member

    Dear junkies,

    I am going to convert my gaff ketch to a hopefully unstayed junk. My masts are currently these tabernacle-stepped aluminium tubes. Very thick-walled. I understand that junk masts will have to be keel-stepped and tapered. Would it be possible to re-use these masts, keel-stepping them, and using a smaller-diameter upper section of aluminium or wood to have some kind of taper? Or maybe these would be the upper sections? The main is around 16 cm diameter, and the mizzen is around 14cm.

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