Converting 10t gaffer to single mast junk

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  • 27 Aug 2023 17:31
    Reply # 13246307 on 13127979

    I'm glad to be of help. I hope the mast will serve you well. Please keep us posted on your progress.

  • 27 Aug 2023 13:15
    Reply # 13246262 on 13127979

    Thanks that is useful. I think I am in the ball park. Have just used the last of my carbon and created the collar as suggested, it finished at about 5 mm plus the biax. Will get onto the filling and fairing and hopefully start painting in a week or 2.

    Thanks again for your helpful advice over the last few months.

  • 27 Aug 2023 10:37
    Reply # 13246239 on 13127979

    This is not easy to answer. I did a mast 12.5 m long for a 3.5 ton yacht that had 6.8mm carbon uni at deck level. It was designed to be very stiff so some extra material went into the laminate. The 90 deg reinforcements at the base, deck and head were 2000 gr total, 800 inside, 1200 outside. There were bulkheads also at these points.

    For boat like yours I would want 9 or 10 mm at deck level tapering to maybe 4mm at the top. There can be a taper to the mast base also to maybe 6mm.

  • 26 Aug 2023 18:40
    Reply # 13246096 on 13127979

    Great information Rudolph, thanks, I will do that. Do you think the construction as described is adequate, not enough or a bit over the top?

  • 26 Aug 2023 16:00
    Reply # 13246048 on 13127979

    Yes, I would use two of these side by side, so 324 mm wide, and at least 3mm thick.

    Maybe you need to put on a bit of thickened epoxy before you start putting on the first layer if the surface isn't very smooth.

  • 26 Aug 2023 15:40
    Reply # 13246044 on 13127979

    Thanks, I will do that. I have some of the 162mm wide uni carbon left. Would I achieve this by wrapping round and round at deck level? And then biax?

  • 26 Aug 2023 12:01
    Reply # 13246001 on 13127979

    What i forgot to mention earlier is the need for a 'collar' of 90 degrees carbon at deck level to take the loads were the mast touches the deck. You could add that and cover with biax. 

  • 26 Aug 2023 07:47
    Reply # 13245989 on 13127979

    The outside of the whole mast has about 6 mm of carbon plus another layer at the deck tapering out. What are your thoughts on its strength?

  • 25 Aug 2023 21:36
    Reply # 13245847 on 13127979

    Hi Jim, that sounds good. Did you put some carbon at deck level on the outside too? That would spread the load and copy the inside laminate.  

  • 25 Aug 2023 15:43
    Reply # 13245590 on 13127979

    Hi Rudolph, the mast is 14.6 m long (48"),115mm at the truck, 275mm at the deck and 235 at the step.

    To be more accurate about the wall construction it is about 20 mm thick Douglas fir with internal epoxy fillets and glass tape. At the deck area there is also 660g carbon and 660 g biax glass inside. Outside it is a layer of 660g biax glass then 3 mm of 330g uni directional carbon, another 660 biax glass then 3mm of 330g uni carbon and finished with 450g biax. I used 80 kg of epoxy and a rough guess of its weight is about 250kg (but will weigh when I put it in). I will weigh the old mast and standing rigging when I crane out but think they are heavier. Yes it is lovely and stiff though not the best finish as I left most of the glass and carbon overlaps so when you sight along it there are many small bumps but the mast is straight to the eye.

    Cheers, Jim

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