Forgot password

Sadler 25 conversion..

  • 16 Jun 2020 12:03
    Quote
    Reply # 9040165 on 8800878
    Anonymous member

    ...am thinking out loud, has  anyone used Polypropylene snap wedges at mast step and partners before? 
    https://www.orbitalfasteners.co.uk/products/brown-snap-wedge-packers-198mm-x-42mm-sold-in-tubs-of-100-polypropylene

    any thoughts as to suitability?
  • 14 Jun 2020 17:22
    Quote
    Reply # 9036423 on 8800878
    Anonymous member

    The tapered socket is best done by first making a tapered end plug, installing it in the mast, making a rough oversize hole in the mast step, coating the heel plug with release agent, stepping the mast, then pouring something into the gap. I used castable polyurethane.

    Wedges need a tapered hole, too, both at the heel and at the partners.

    Last modified: 14 Jun 2020 17:29 | Anonymous member
  • 14 Jun 2020 15:24
    Quote
    Reply # 9036242 on 8800878
    Anonymous member

    Thanks David,

    agreed re birch/epoxy, I’m using it as I feel it far exceeds the quality of most ‘marine’ ply (other than high end stuff like Robbins’) and is much better value.

    think I’ll go for wedges into straight sided hole at mast step- easier than fabricating tapered socket with my limited skills..
  • 14 Jun 2020 12:45
    Quote
    Reply # 9036046 on 8800878
    Anonymous member
    1. There's a huge bonding area under the mast step. If 50% of the glass is exposed, that's plenty, and I can't see a need for bolts as well. Birch isn't classed as a durable timber, so will need a good soaking with epoxy.
    2. Aluminium tube takes compression loads well, so putting it into a socket is good for it. It doesn't need a plug to support radial loads.
    3. What's not good is if the end of the tube is allowed to move a little, grinding away at the surface it's bearing against. A tapered wooden plug mating with a tapered socket is good (I have that on Weaverbird). Tapered wedges, as for the partners, are good, so long as they are tight and don't move. There are probably other good ways of eliminating movement at the heel, too.
    4. Wedges with ~100mm length of contact will do a good job of spreading the load over the mast wall. No need to bond anything to the mast.
  • 14 Jun 2020 11:02
    Quote
    Reply # 9035954 on 8800878
    Anonymous member

    Hi folks,

    I’m slowly getting on with my conversion. 

    I ground away at the flowcoat on the cabin sole where the mast step will go. The substrate at that point is quite uneven, so although glass was quickly exposed in some places, plenty of flow coat remained in the troughs between peaks (I’ve added a couple of photos to my album).

    I’m following Arne’s method for the step, building up layers of birch ply. 


    I have some questions..

    1. Is it important to grind back to bare glass here or will it be ok to leave some flowcoat as long as it’s ‘keyed’ for the epoxy to grip? (I will additionally be bolting my mast step to bulkheads fore and aft)
    2. My mast (lampost) is 199mm diameter and 3,5mm thick at base. Should I insert a wooden plug in it to a short depth at the base, or is it robust enough as is?
    3. Should I make the socket hole in the step oversize to take shims/wedges for a snug fit, or just size it for the bare mast?
    4. At the partners level should I add thin plywood splines glued to the mast for the wedges to bear against?


    I had a bit of drama at the sailing club the other day. The trolley jack I was using to jack up one of the twin keels to level the boat let go with a snatch and dumped her down hard. I had a few anxious days to wait before a surveyor (who happens to be a club member) could take a look. To my relief he gave her a clean bill of health, dismissing my concerns about a few cracks in the gel coat towards the bow as probably caused by too short a riser on my mooring chain, and only of cosmetic concern. I’d identified the mooring issue last season after noticing that at the top of a spring tide my mooring buoy was completely submerged. The riser was at the club regulation length, but they’ve agreed for me to add a couple of meters for this season.

    The lesson I’ve learned re trolley jacks, is oil them first!
  • 31 May 2020 07:29
    Quote
    Reply # 9004194 on 8800878
    Anonymous member

    You know you're old when...

    1. ... you have to sit down to put your trousers and socks on.
    2. ... historical researchers start delving into things you did nearly half a century ago.
  • 31 May 2020 06:47
    Quote
    Reply # 9004176 on 8800878
    Anonymous member (Administrator)

    First Sadler 25 JR conversion.

    Historical matters are always of great interest to me, and while delving for something-or-other quite unrelated I stumbled upon one of the early JRA fact sheets, which contained an index of newsletter articles. What caught my eye was the third-ever JRA Newsletter, with an article by someone called David, about a junk rig for a Sadler 25. As it happens, it was also maybe the first-ever published piece on the evolution of a junk wingsail.  That's going back to 1981.

    There's also a boatbuilding article by someone called Annie, and a letter by Blondie Hasler describing a day trip on his Kingfisher 20, with Bill Belcher as companion.

    What a joy to come across these little gems.

    Last modified: 31 May 2020 07:04 | Anonymous member (Administrator)
  • 28 May 2020 10:15
    Quote
    Reply # 8997323 on 8800878
    Anonymous member (Administrator)

    I too think that for ultimate strength of the yard, it would be wiser to have the thin tube on the top. However, we should be working far, far from breakdown loads here, so I don’t worry about that.

    As for aerodynamic benefits, my guess is that Slieve is right, but it will be fun to try, anyway. I plan to renew the lashings at the sling-point this summer (Dyneema, this time), so may just as well turn the yard upside down while I am on it.

    Arne


    Last modified: 28 May 2020 10:15 | Anonymous member (Administrator)
  • 28 May 2020 08:58
    Quote
    Reply # 8997225 on 8800878
    Anonymous member

    ...smaller one on top it is then, thanks guys
  • 28 May 2020 05:35
    Quote
    Reply # 8996984 on 8800878
    Anonymous member

    Structurally the larger section will be better in compression so the smaller tube should be on the tension side of the yard, the top.
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

                                                              Site contents © the Junk Rig Association and/or individual authors

Powered by Wild Apricot Membership Software