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Comments invited on schooner sailplan

  • 01 Apr 2012 23:43
    Quote
    Reply # 874040 on 873493
    Deleted user
    Annie Hill wrote: Gary - Jay, like most designers, is very optimistic about how light the finished boat will be.  Expect her to displace quite a lot more and raise your boot-top accordingly before you even launch!
    Yes, have anticipated that, the anti foul has been painted 10 - 12cm above Jay's mark already.
    Last modified: 01 Apr 2012 23:44 | Deleted user
  • 01 Apr 2012 23:41
    Quote
    Reply # 874039 on 873996
    Deleted user
    Kurt Jon Ulmer wrote:
    With 5:1 halyards, I think you may be frustrated getting yours to fall obediently. 
    Thanks  Kurt.
    I hadn't thought of that. That's an argument for going back to winches and 3:1. Its early days yet and a lot hasn't been decided.
    Only the mast positions have been set.

    I did consult PJR for acceptable angle of the sheets and the sail plan is within the guidelines. I'm in the process of drawing up the panels so haven't decided how much rounding on the upper panels yet, probably not a lot. I realise for off shore sailing upwind performance doesnt count for much, but we will be doing a fair share of coastal trips, which means beating to weather to get home! So I am a fan of a foil shape or two.


    Last modified: 02 Apr 2012 01:35 | Deleted user
  • 01 Apr 2012 21:22
    Quote
    Reply # 873996 on 872150
    Anonymous member
    Hi Gary & Susie,

    Top panels and camber - My intuition and my experience with mehitabel convince me that your top 3 panels would develop a lovely smooth and powerful fanned camber if cut flat. If each of those three panels has camber built in, I humbly suggest that the smooth shape of fanned camber and its effectiveness will be hurt by dips and bumps, especially when reefed down to 3 or 4 panels. Other opinions exist, though.

    Structurally, tight flat sailcloth distributes strain; easing panels out with built-in camber concentrates strain in spars and edges. In the top part of the sail, I'm happiest with flat panels.

    Yard weight - I question altogether the need for lightness in yards. I want ours to lay down when the halyard is let go, and to be bomb-proof against the varying forces when raised up. With 5:1 halyards, I think you may be frustrated getting yours to fall obediently. In tough weather, reefed, the weight of a yard is low, yes? A place to overbuild for confidence, rather than tweak a few kilos for any reason, I think.

    Yard length - The shortness of your yards is, in my opinion, an aesthetic success but perhaps a structural mistake, in that it transfers compression (and other yard forces - these things don't sit still up there!) to the top battens, and adds tension to the leech of the top panel. Mehitabel's top batten is two battens. Just an idea.

    Sheeting - I've come to appreciate the anti-twist 2-point and equal-power 3-point spans described in PJR chapter 4, in our rig. I can't tell from your drawings if you have ample drift to the deck, but it's important, whatever sheetlets are used. Sheeting points and height of the clew above deck deserve a lot of refining effort, I reckon. You've probably made sure of the clearances... yeah, I probably didn't need to bring it up.

    It's a beautiful-looking plan, with some visual relief from the sheet-of-plywood effect some of us sail around with. She'll be great.

    Cheers,
    Kurt
  • 01 Apr 2012 06:11
    Quote
    Reply # 873637 on 873497
    Anonymous member
    Annie Hill wrote:
    Paul Thompson wrote: since the foresail is also the sail that you'd mostly be using in heavy weather (running) the extra strength would not come amiss.

    Not necessarily, Paul.  We ran under mainsail on Badger.

    Grasshopper,

    Yes, I am aware of that but most boats (non junk) generally run under the jib and I tend to think of the foresail as similar to the jib when it comes to junk schooners. It'd be interesting to know what others have done.

    I'll know what works for LC soon enough and I'm sure I'll have an interesting time learning her quirks and foibles under her new rig. I'll most certainly will be seeing if LC is also happy to run under the main.
  • 01 Apr 2012 01:08
    Quote
    Reply # 873497 on 873421
    Anonymous member
    Paul Thompson wrote: since the foresail is also the sail that you'd mostly be using in heavy weather (running) the extra strength would not come amiss.

    You then only then need to carry one size of spare which would simplify things a bit.

    Not necessarily, Paul.  We ran under mainsail on Badger.

    But being able to swop battens from one sail to the other makes a lot of sense.
  • 01 Apr 2012 01:04
    Quote
    Reply # 873493 on 872604
    Anonymous member
    Gary King wrote:She has a 'cruising' displacement of 4,750 kg. (Which I deduce from Benford's site, means she is 3,500kg empty). Pretty lightweight, I imagine this hull needs a heavy load, dories are supposed to perform better that way. I've chosen the fin keel design with lead as low as possible, I think dories need all the help they can get regarding stiffness.... So hope she performs well enough.

    Gary - Jay, like most designers, is very optimistic about how light the finished boat will be.  Expect her to displace quite a lot more and raise your boot-top accordingly before you even launch!
  • 01 Apr 2012 00:22
    Quote
    Reply # 873478 on 872150
    Deleted user
    Thanks Paul. Well, I am a graphic designer, I even made the forward hatch cover art deco.. can't help it...

    I've decided to make scale model of one of the sails. To see if it can hang straight, with THP and YHP, without HK parrels. There might be a difference between the shorter yard and the full length yard on this HM style plan, I don't know. Thus the model.

    I'll take you up on the tube sizing for the fore sail, as well as David's suggestion that spanned downhauls are rubbish in practice.
    Last modified: 01 Apr 2012 01:02 | Deleted user
  • 31 Mar 2012 21:17
    Quote
    Reply # 873421 on 872150
    Anonymous member
    Gary, your sail looks good. You obviously have an artist eye. I have nothing to add to what already has been said except to suggest that you consider making the batten sizes for the main and foresail identical. There would be very little increase in weight and since the foresail is also the sail that you'd mostly be using in heavy weather (running) the extra strength would not come amiss. You then only then need to carry one size of spare which would simplify things a bit.
  • 31 Mar 2012 12:03
    Quote
    Reply # 873152 on 872819
    Deleted user
    David Tyler wrote:
    • I'd sheet both sails further aft than you've indicated; the foresail directly under the tack of the main, and the main back near the rudder head. I'd recommend 5 part sheeting, to three anti-twist spans (PJR fig 4.31). I don't think 6 parts are needed.
    Happens I'm confusing 6 part with 6 point sheeting. Yes, 5 part sheeting attached to 6 battens, is what i would have meant.
    Thanks for the input so far folks, I'm still working on design, ie. sheeting and sail panel drawings.

    Looks like the top 2 panels being bigger than the fabric will need to be broad seamed, which means the same panels on the smaller foresail will need broad seaming too, to keep balance.
  • 30 Mar 2012 22:21
    Quote
    Reply # 872819 on 872150
    Anonymous member
    I like the shapes and proportions of the sails very much, Gary. I would think that it's safe to go ahead and cut cloth.
    I have some comments on the rigging, though.
    • I'd make the standing parts of the topping lifts longer, to reduce the risk of fouling.
    • I'd sheet both sails further aft than you've indicated; the foresail directly under the tack of the main, and the main back near the rudder head. I'd recommend 5 part sheeting, to three anti-twist spans (PJR fig 4.31). I don't think 6 parts are needed.
    • I've used downhauls on my wingsails, where they are a necessity to keep the luff straight and round. I haven't got on at all well with spanned downhauls, and ended up with only using them on the very topmost downhauls, which were seldom used. For the lower reefs, single downhauls were much more user-friendly, even if they involved more rope and hardware. I've tried spans in the form of the anti-twist sheet span, to get a stronger pull on either the top or the bottom batten of a pair, but I can't say that it made things any easier. With a single downhaul, you simply haul taut and belay. With a spanned downhaul, you have to juggle with the downhaul and the halyard until you have the lower batten right down and the luff above it taut, and it takes some doing.
    • Arne will be trying to reduce his dependence on HK parrels when his sailing season begins again. 
    • I've found that luff hauling parrels can take the place of both HK parrels and downhauls, when applied in the right place at the right tension. They haul back, down and in, at the same time. I'd treat all of these items - downhauls, HK parrels and luff parrels - as things to be set up on a temporary, experimental basis, while you find out what suits both you and Ashanti best.
    All in all, I think this is going to be a good-looking rig that will sail well. 
    David.
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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