Project Mage - Part 1: Sizing, Scaling and Fiddling.

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  • 05 May 2021 00:47
    Reply # 10442358 on 6977997

    I have seen a wooden top section fitted to an aluminium lower section in which the alignment was not quite perfect. The mast still worked quite satisfactorily anyway - I do not think perfectionism is all that necessary.

    However, near perfect alignment can be achieved quite easily if you prefer.

    I joined an aluminium top section (with spacers to fit) to an aluminium lower section, and achieved alignment while making the join, by reversing the top section, sliding it into the lower section, and using the lower section as a mould.

    The top end of the top section (deep inside the lower section) was held concentric by a couple of rope grommets. Actually, one would do. In my case, the epoxy/wood annular spacer was cast in this position.


    The above diagram is not to scale or in proportion, but shows how the fitting part is aligned.

    When the fitting is complete, the top part is taken out for the last time and reversed, then fitted back into the lower part. A conical fairing (made of wood and epoxy) is added to the top section, to smooth the transition between the two outer diameters.

    There are some matters to be careful of if you are doing this by casting with epoxy, as I did. I will skip those details because there should be no issues if you are doing it with wood.

    Fitting a wooden top section should require no casting, and be a simple matter of trial and error, whittling down the fitted part until it fits into the outer tube. The other end is supported inside the bottom tube by rope grommets, to a sliding fit, so the top section can be slid out to work on, then slid back in for another try etc until it fits. Alignment is maintained by the rope grommets which keep that top section always concentric with the outer lower section.

    And also, because one part is inside the other, considerable workshop space is saved!)

    The diagrams show a simple tube for the top section, but I would expect an wooden top section to be tapered, so that the top of the top section fits easily into the aluminium lower section (held concentric by the rope grommets) while the bottom of the top section -the part being worked on - is, initially, too big to fit and simply needs to be trimmed down, parallel over the length which will provide "bury" when it is reversed, until it fits.

    A massive amount of gluing of the two sections is not required as the outer cone, which is added afterwards, prevents the top section from telescoping downwards due to the tension on halyard, lifts etc - just a few dabs of polyurethane glue should be enough to hold the two sections together, and withstand the rotational forces (which must not be forgotten) which halyards and lifts will also cause the top section to impart to the lower section.

    I should think a wooden top section fitted this way would be quicker and easier than the aluminium top section which I fitted by casting an annular spacer. In both cases the alignment will be near perfect. 

    Last modified: 05 May 2021 01:31 | Anonymous member
  • 06 May 2021 03:44
    Reply # 10446510 on 6977997

    Graeme - thank you for that explanation. I can see how that might work. Although - I am trying to understand why you wouldn't use epoxy (can you tell that i'm no carpenter?)

    Last modified: 19 May 2021 23:40 | Anonymous member
  • 06 May 2021 09:03
    Reply # 10447144 on 6977997

    Hi Adam. We seem to have a custom of not using surnames on this public forum. Its not an issue for me, but if you want to conform you can click on the edit button and deal with that.

    I am not sure which use of epoxy you are referring to. I fitted one tube into another by means of an annular packing piece made from wood, epoxy and glass which I can explain in more detail if you want to do that. However my precaution was that special care must be taken to make sure the casting can be released from its mould, the outer tube. I used two layers of baking paper plus a release agent.

    Making the top part out of wood makes good sense to me, although I haven't done it.

    When it comes to joining the two parts together, I have used epoxy, but I am reliably informed that a better way of gluing wood to aluminium is to use a polyurethane rubber (adhesive sealant). 

    Here in New Zealand we can not get tapered aluminium poles.

    Edit: I am outside of my own direct experience by recommending polyurethane rubber (adhesive sealant) - I could not remember the name of the recommended product but got it now: Simson adhesive sealant. I am assuming this is a polyurethane rubber, but open to correction. This is the recommended goop anyway.


    Last modified: 06 May 2021 21:43 | Anonymous member
  • 19 May 2021 23:40
    Reply # 10524320 on 6977997

    Corrected to omit last names. 

  • 05 Jun 2021 00:23
    Reply # 10592752 on 6977997

    Sample sail material for the rig. 

    I think I'm going with the Top Gun.

    Odyssey feels too light and the sunbrella too heavy. 

    Colour will be red. 

    1 file
  • 05 Jun 2021 00:25
    Reply # 10592756 on 6977997

    Batten and Yard tubing. T6061

    1 file
  • 30 Aug 2021 03:40
    Reply # 10967863 on 6977997

    Photo of my existing Mainsheet and traveler arrangement on the C&C 25 - this strikes me as being a perfect pre-existing arrangement for managing my sheets when the sail goes on. I can use the sliding traveler block to secure the sheeting system to the transom. 

    1 file
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