Hybrid mast making

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  • 21 Sep 2015 13:44
    Reply # 3536422 on 3500760

    Good to see your photos.

    Was the taper cut by eye to a drawn line?  We may see this is your following posts: will the timber socket be cut with a shoulder so as to be flush with the outer face of the aluminium?

    As you have chosen a hybrid, I assume that you have found it to be the best combination of ease of construction / cost /  weight. Could you refresh us with your thoughts on the advantages of a hybrid mast, say over:

    - Using a smaller diameter aluminium top section. (sounds very simple, though will not look as good)

    - An all timber staved mast.  (once set up to make the top section, why not continue foe the whole mast?  In theory, the correct taper over the whole length may give a more efficient structure and less weight?)

    Cheers  Mark

  • 20 Sep 2015 08:55
    Reply # 3534463 on 3500760

    David,

    Great photos of your mast under construction. Good clean stuff.

    Having forgotten to add the link to my sketch, I should start a new thread when I have got my act together....

    Pol.

  • 20 Sep 2015 01:15
    Reply # 3534319 on 3500760
  • 20 Sep 2015 00:33
    Reply # 3534314 on 3500760

    David,

    Here's the link to the KetchSketch - proposed JR conversion of our 29' gaffer. Apologies for the slightly muddled markings on this. It is about 450/150 squ feet. Since you mentioned mast making and ketch rig I hope I am excused for muscling in on you posts here.

    I do have quite a few questions - weight aloft, double sheeting, bumkins etc - so I'll start a new post when I'm a bit better organised and have had a good look at what has already been discussed on the forums!

    Pol.

  • 20 Sep 2015 00:02
    Reply # 3534290 on 3500760
    David, I am excited to hear that you are  putting a ketch rig in TYSTIE. Your hybrid mast is aluminium with a wooden topmast? (I tried to look at some photos in your profile but I could sit here all night - our connection is v poor - so I am afraid I had to give up on that...) We are planning a JR ketch conversion for our gaffer ANNIE, a Cornish Pilot 30 (Cornish Crabbers 1985). I have a very amateurish sketch of the proposed rig, which I will try post a link to in a mo.. I thought my AR of roughly 2.5 on the main was a little on the 'tall' side so I am delighted to read your comment about high AR sails! There are quite a few points on which I'd really like those much more experienced than me to comment on, but I'll start by posting the sketch on here if I can raise the steam to do it. 

    It is great to hear of the SibLim project via your and Annie's amazing commentary. Your efforts are greatly appreciated.

    Best wishes,

    Pol.

  • 19 Sep 2015 21:55
    Reply # 3534162 on 3500760

    I'm working on my hybrid mizzen mast. I'm using the six staved method (fig 8.13a in PJR), that Reuel Parker describes fully in his book "The New Cold-Molded Boatbuilding", with thirty degree angles on the edges of the staves. It's been quite a quick and straightforward process to shape up the staves, drawing the curve for a barrel taper onto the outer, planed face of a stave, cutting it with a hand-held circular saw set at thirty degrees, then fairing the curve and correcting the angle with a hand plane. 

  • 29 Aug 2015 20:58
    Reply # 3501412 on 3500760

    Dennis,

    The hinges themselves were strong and sound, though I didn't like the "clickety clack" any more than I like cambered panels emptying and filling with a bang. Two after battens broke in Hawai'i, and I fixed them up with some douglas fir replacements, but other after battens are also bent, having yielded in the tropical sun, and would need replacement if I stayed with the single sail. There was also a problem with the battens rotating about their long axis under certain conditions, and this could only be cured by replacing the carbon battens, of rectangular cross section, with round battens and conical hinges.

    That sail was a success on two counts: 1) I salvaged, out of the stalled wing sail project, a rig that was good enough to make the voyage from Canada down to NZ. 2) I discovered, quite by chance, a configuration that was easier to handle than any other rig that I've used, with hardly any attention being being needed to hauling parrels.

    However, it seemed that the true CE is further forward than that of the wing sail, and so in light airs, there is unacceptable lee helm when on the wind (but no problem in moderate and strong breezes). I had always intended to make a wing sail ketch rig, but couldn't face the extra work of making the mizzen. Now, I just have to do it, to get myself a rig that I can continue to use as long as I keep sailing Tystie. The only other option to improve the helm balance would be to go back to a lower, wider, single sail, but with advancing years and decreasing strength and stamina, this is not an option that I can take. I haven't done any more than sketch the ketch rig so far, but now that I am a convert to high AR sails, being so much easier to handle, I will certainly be using the extra length of my extended mainmast to keep the chord of the mainsail down to 4 metres, and the mizzen will be of similar AR, 2.75.

    Last modified: 29 Aug 2015 21:14 | Anonymous member
  • 29 Aug 2015 15:31
    Reply # 3501113 on 3500760

    David,

    I may have missed a few posts. What is the upshot on your hinged batten project?  I heard some broke.  Any further developments?

    Dennis

  • 29 Aug 2015 04:33
    Message # 3500760

    Yesterday, Annie and I ordered three 152mm dia x 5mm x 6 metre tubes, 6061T6, from Ullrich in Whangarei. That's one mast for SibLim, one for Marcus's Sweet Thursday, and a new mizzen mast for Tystie. 

    So now we're all committed to making rigs at some time in the near future!

    [edit: 6 metre tubes]

    Last modified: 29 Aug 2015 20:38 | Anonymous member
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