Single-handed Skiff

Discussion in 'Sailboats' started by nacra5.8, Jun 17, 2012.

  1. nacra5.8
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    nacra5.8 Junior Member

    Alright guys, I'm going to try and add some more freeboard and flare- shouldn't be too hard.

    For launching/retrieving/capsizing: I will often have other people to help me, and I'll almost always be beach launching. I feel like I could raise the main, roll the boat into the water, let it capsize, bring the dolly back, out the rudder and daggerboard in, right the boat and do a sort of unglorified dive into the back of the boat. Coming back in, I could also capsize the boat again as I soon as I jumped out. If anyone has better ideas 'm open to suggestions here.

    During capsizes, I'm probably going to have a Swift Solo-esque ladder-type righting line to climb up, and, if needed, a catamaran righting bag.

    I'm going to build a luancher bag similar to the Swift Solo design on their website, but with extra reinforcement, because it will take the forestay loads too. I'll be using an extra long bag at first (built for a kite much bigger than mine), so I expect that to cut down on friction.

    Doug- AoA is tiller extension adjustable. I haven't calculated how much I'm expecting, again It's off an I14 so do you think I might want to cut a bit off of the foil ends?
     
  2. nacra5.8
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    nacra5.8 Junior Member

    Also, Steve- On the Cherub website it definitely says to use around 80 kg/m3 foam- but since this boat is going to have lighter loads... you think its OK to use 55 kg/m3? I only ask because I can get it so much cheaper than 80 kg. I also un
     
  3. nacra5.8
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    nacra5.8 Junior Member

    -Veed the centerline a bit.
     
  4. nacra5.8
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    nacra5.8 Junior Member

    Also, has anyone tried this resin before, its super cheap so I'm kind of wary of it, but if its reliable it would help me cut my costs down a fair amount. I'm currently planning on using System 3's laminating resin- seems like good stuff and it works well with their WR-LPU which is what I'm using for paint
     
  5. nacra5.8
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    nacra5.8 Junior Member

  6. Steve Clark
    Joined: Jul 2004
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    Steve Clark Charged Particle

    80 is less likely to dent and sheer. Probably a better choice for the skins.
    What matters most with epoxy for these kinds of jobs is heat distortion temp.
    or T sub G. Thin skins get hot and if the whole thing gets soft, well it sucks.
    Once saw a foredeck pop off a boat in a parking lot.
    You will learn a whole lot, enjoy the ride.
    SHC
     
  7. gggGuest
    Joined: Feb 2005
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    gggGuest ...

    It depends on how much you like filling and fairing dents:-( Actual core failures are relatively unusual IME*, but bashes, dents and holes are quite common, and I fear a 55kgm3 boat could start to look like a golf ball after a while.

    And as Steve hints: always put a breather into all watertight compartments: amazing how much pressure can build up.

    JRD - yes, I was especially thinking Woof and the like, but some of the Pom development classes ban hollows in the sections and get a lot of reserve stability from the flare too.

    *I have had a core failure as it happens, but it was where the worst of the trailer loads came (even with generous area and padding) and after well into three figures of races and four figures of miles on the trailer to venues.
     
  8. JRD
    Joined: May 2010
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    JRD Senior Member

    Good idea using it as a forestay attachment.

    No comment on if you should cut some off, but as I understand it the 14s now have a foil which matches the transom width at water line. This is used upwind to pull down the pressure wave and provide an effective extra waterline length. The hulls are now designed to maximise the foil benefit, rather than it just being an accessory.
    Of a practical note, keep in mind that the end of the foil will crunch into the ramp with every wave when you tip the boat on its side to launch, so shorter may be better for practical reasons. Moths are similar, but are so light they can be carried like a sailboard, so you dont need the dolly.
     
  9. Doug Lord
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    Doug Lord Flight Ready

    ==========
    JRD, read Ellways comments on the rudder t-foil above( if you haven't already )-interesting and technically astute.
     
  10. nacra5.8
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    nacra5.8 Junior Member

    Doug-
    I ran through SA/D and DLR once, came up with 10.29 for my S# (with 180 pound crew). Is crew eight calculated in the ratios?
    SA/D: 38.6
    DLR: 0.1607


    I also fond two other cheaper (than West or System 3) epoxies, both with better reviews than the one i posted earlier:
    http://uscomposites.com/epoxy.html


    http://www.epoxyusa.com/category_s/3.htm

    I'll look up their info later.
     
  11. Doug Lord
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    Doug Lord Flight Ready

    ==================
    Yes...
     
  12. Doug Lord
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    Doug Lord Flight Ready

    Dinghy Specs

    N, here is a table of dinghy specs compiled by a member here, and another set of statistics compiled for the IC:
     

    Attached Files:

  13. nacra5.8
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    nacra5.8 Junior Member

    Alright, I've been working on the design a bit- here's a major change I made. basically, shrunk the waterline beam from around 2' 6+" to around 2 feet. Shrunk overall beam too, but not as drastically, increasing the flare. I'm not sure if this is better, worse, or a good idea that was a bit too drastic... Keep in mind, windspeeds of less than 10 knots I essentially don't care about. I either won't sail on those days, or will take the Nacra out to play by myself. the most common conditions where I sail are going to be 15 gusting to 20, but often higher.
     
  14. nacra5.8
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    nacra5.8 Junior Member

    Here's a few screenshots.
     

    Attached Files:


  15. gggGuest
    Joined: Feb 2005
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    gggGuest ...

    I'm not sure that isn't the wrong way to go.

    Consider: narrow beam makes for low wavemaking resistance, but if you are talking about 15 20 knots plus you are more concerned with planing behaviour. Planing, AIUI, is about lift, and the longer and thinner you make the boat and the narrower the dynamic lifting surface then the worse the aspect ratio and the worse the lift/drag. So for planing conditions a shorter fatter boat is good, but it will stick in the light stuff.

    There's also the philosophical point: why would you want an ultra thin monohull to slice through the waves with minimum wave drag when you already have a multihull that will slice through better than any mono? The point of a planing boat is surely that it can go bouncing over the waves in a way no conventional multi can manage.

    Designing for wind also brings us onto rocker. There's a basic tradeoff point in that the less rocker you have the faster you will go, both forwards and downwards towards the bottom of the sea. More rocker reduces both speed and pitchpoling.

    There are also subtleties. The classic and fastest rocker distribution seems *to me* to be to have the max rocker under the mast, with the amount of curve reducing steadily going in each direction. However there was a definite trend in the UK twenty years back for boats with a lot of rocker towards the stern. This was slow. It could be very slow. But it was also very safe, and such boats could be driven very hard indeed.

    My impression is that it sort of came to a head in the pre amalagamation 14s. The Australian boats of that era were low rocker wedges and rotten 'ell were they fast. They were also b*****ds for going down the mine. The UK boats were bananas with rocker aft, and dog slow, but they could also be driven very hard.
    At the worlds where they came together the very best Australian boats disappeared off over the horizon and were not seen again, and the top English crew, who had trained very hard and were possibly amongst the best sailors in the world at the time failed to win a single race. The rest of the fleet however was completely mixed up together, because the Antipodean boats were backing off trying desperately to survive, whilst the UK boats were making the very best of what speed they had. Maybe this is exaggerated a tad, but the principle holds.

    We can talk about section shapes too, but that's enough of an essay for now.

    SHCs thoughts on these matters would be worth a great deal: his experience is far broader than mine.
     
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