Origami rig comments

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  • 28 Mar 2021 20:51
    Reply # 10244944 on 10239601
    Anonymous wrote:

    Doug, also you may not be aware, but the SJR as designed by Slieve already eliminates all those hauling parrels you refer to. The sail design/top panel/yard attachment point are worked out so the sail drapes properly without them.

    I think (you might know better having one to play with) that part of the reason it hangs well is that the top panel is still angled and the halyard is shorter than the rest of the battens. So the OP idea of just adding panels to make the sail might cause binding without at least one odd panel on top.

    I think the Origami rig can be further simplified. Does the D-former actually make any real improvement, in practice? I doubt it, and would far prefer to keep the plain full length battens as in the SJR (spit junk rig). KISS.

    I am not sure which is simpler, I have had a similar idea for a while with the addition that one side of the D-former would be removable (and I just had a square/rectangular hole) so that any batten might be removed without having to dismount the mast. A D-former would not work with a tabernacle I think but a tapered mast should be fine, the D would have to be the size for the widest part is all. In a hybrid mast more care would have to be taken at the join, though I guess that is the case anyway.

    I think the D is simpler than the ropes, straps or what have you that hold the battens to the mast and position it for and aft. The batten to D-former join probably evens that back out or makes it more complex. Also on the plus side for the D-former, is the storage of spare parts would be easier as spare battens could be 1/3 ish the size. So I am not sure which of the two comes closest to KISS.

    hoped-for dinghy rig which could be quick and easy to make - and able to be assembled or dismantled in less than 2 minutes. So far its just a daydream - nothing actually tried yet.

    This is another place the D-former might be less practical. I would imagine the sail bundle, battens and all might be folded flat against the mast and left all in one piece for transport and storage. With the D-former, one would have to have a tie around the D-formers to keep them in order and lift the mast out from the middle. Really, trying it both ways for a few trips would tell and even then, a person's preferences might get two answers from two people.

  • 27 Mar 2021 01:40
    Reply # 10239601 on 10239242
    Anonymous member (Administrator)

    Hello Doug. Welcome.

    What fascinates me about the origami jib is its uncanny resemblance to the usual much more complicated-to-make 45 degree shelf jib, when inflated.

    I'd like to try one on a dinghy. Paul admits to an unavoidable small wrinkle near the luff, but it probably doesn't matter, and I can't see it anyway, in the photos (JRA Mag #85) it looks pretty good.

    Doug, for a full size sail it is said that its best if the orientation of the cloth is parallel to the leech of the sail, so if there is batten rise (which seems to be usual) it may not be quite so simple to make full-width-cloth panels as you describe - you'd need to check that with someone who knows more about sail-making, I am not sure. (I notice Paul's origami "hybrid" rig seems to have zero batten rise.)

    Doug, also you may not be aware, but the SJR as designed by Slieve already eliminates all those hauling parrels you refer to. The sail design/top panel/yard attachment point are worked out so the sail drapes properly without them. (Well, almost). Instead, however, you still have to have two paired-spanned-parrel-downhauls (see Slieve's notes for explanation) which need to be attended to when reefing. I suspect a dinghy with an un-tapered tube mast would probably get away with very short standing batten parrels - but might still need downhauls, I haven't tried it yet.

    I think the Origami rig can be further simplified. Does the D-former actually make any real improvement, in practice? I doubt it, and would far prefer to keep the plain full length battens as in the SJR (spit junk rig). KISS. A tiny little bit of asymmetry doesn't hurt, and I bet you couldn't tell the difference between port tack and stbd - I can't anyway. And although the D-former might eliminate the need for batten parrels, I suspect downhauls MIGHT still be needed - it would be great, for a dinghy at least, if downhauls too could be eliminated.

    I see Paul's origami jibs, in a SJR arrangement (with full length battens and not the D former), with short standing batten parrels and PERHAPs just one spanned-pair downhaul (hopefully not even that) as a starting point for a hoped-for dinghy rig which could be quick and easy to make - and able to be assembled or dismantled in less than 2 minutes. So far its just a daydream - nothing actually tried yet.

    By the way, I've never had a fan-up with my Amiina Mkll SJR - touch wood! I currently remain hopeful that the planform eliminates it - maybe I'd better not speak too soon! Jami? Edward? Dave D? James? Any fan-ups yet?



    Last modified: 29 Mar 2021 10:32 | Anonymous member (Administrator)
  • 26 Mar 2021 23:53
    Message # 10239242

    Hello, I'm a new member, wanna-be cruiser with just about zero hands-on experience in sailing other than a few rides on charter boats, but a seasoned engineer in aerospace (lots of rocket propulsion design and flight testing, including six flights in the right seat of the XCOR Xracer).

    I'm fascinated with the simplicity and modularity of Paul McKay's Origami Rig. A sail of arbitrary height could be assembled from as many jib and main panels as the mast could support, along with a batten assembly for each panel. Obviously the panel height can be selected to juuust fit within the width of a standard bolt of cloth, and the overall sail plan would be designed by the batten count and the jib + main panel lengths, producing an admittedly boring hershey-bar sail- but color patterns can be cheerfully individualized. All the sail's parts can be made by essentially assembly-line methods and built up as needed, and those D-shaped formers (issue 85, p5, fig 3) make the sail's performance consistent and improved on both tacks. On a cruise, any damaged parts could easily be swapped out with spares.

    Heck, panels and battens/D-formers could be built from local materials pretty much anywhere in the world, with no need for finicky sail pattern layout and large scale precision sewing. "Field expedient repairs" seems like a rallying cry for the DIY cruiser.

    Won't most of the various parrels and parrel hauls be eliminated by the D-formers? It seems that the luff, tack, and yard hauling parrels would be unneeded since the sail's fore-aft position is fixed- no need to monkey with it if the jib keeps it balanced and holds the helm forces near zero. Hong Kong parrels also vanish due to the split, too- at least it appears that McKay's Miranda doesn't need them. The function of the batten parrels is subsumed in the D-formers, of course.

    Arne Kverneland's Fan-up preventer Mk1 might be the only other non-standing rigging needed. Dreaming of going cruising and being as lazy as I can get away with, I like the idea of deleting most of the strings, and I feel fortunate to be arriving on the scene after a lot of smart people have solved the big problems.


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