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Aviateur 5.70 Conversion

  • 22 Nov 2013 20:37
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    Reply # 1444304 on 1418008
    Anonymous member (Administrator)

    Stavanger, Friday

    Hi Antioine, first of all, I like the Aviateur design a lot. It seems that the use of twin rudders handles these unbalanced hulls quite well.

     

    Now, have I missed something? Before I could have any opinion about sail area and the usefulness of the boat, I would need to know what sort of sailing you have in mind:

    How long distances do you plan to sail in one go, what sort of performance do you expect or need, what sort of boats are you used to, are you a sportsman and young, is it imperative that the keel can be raised, do you want to build a boat because you like to build boats, do you have deep pockets… questions like that. That boat appears to provide more speed and fun than offshore comfort, for sure…

     

     

    For my own part, my newest boat, Frøken Sørensen, 6.5m, 740kg netto, no ballast, now carries a 20sqm JR. If I knew that she had a ballast bulb of 200kg+, down there, then I certainly would have added another 5sqm, but then I only sail FS inshore. As for sail area itself, the sky is the limit (almost), but unfortunately, there is a limit to how tall and heavy mast you should fit. If you can afford a lightweight carbon mast, then suddenly it makes sense to rig with a bigger rig.

     

     

    Anyway, good luck!

    Arne

    Last modified: 22 Nov 2013 20:38 | Anonymous member (Administrator)
  • 22 Nov 2013 16:32
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    Reply # 1444140 on 1418008
    Anonymous member
    If you really want to cruise a long distance in a very small boat, I believe that you need to go right to the other end of the spectrum of boat designs, and look at designs like John Welsford's Swaggie , Sundowner or Penguin to get enough carrying capacity and seaworthiness.

    You might also study the small boats that have achieved long distance cruises, such as Trekka and Bris II

    In more modern self-build designs, you could look at the Selway Fisher Pioneer 21
    Last modified: 22 Nov 2013 19:03 | Anonymous member
  • 22 Nov 2013 07:42
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    Reply # 1443910 on 1418008
    Deleted user
    I suppose you may be right. I am currently looking to find a way to sail the boat a little, to see how it behave. In a few weeks, there is a nautic exhibition in Paris, and the yard will be there. I will than have a better look at the boat.
    May be a narrower boat would be less fast but more maneageable alone and cruising ?
  • 24 Oct 2013 19:08
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    Reply # 1420656 on 1418008
    Anonymous member
    I would only use this type of hull for a single-handed, long-distance race. I don't think it would make a good long-distance cruiser, if that is your aim?
  • 24 Oct 2013 07:35
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    Reply # 1420215 on 1418008
    Deleted user
    Thanks for these advices.

    Building its own windvane seems a little complicated for me but why not.
    May be I am just not choosing the right boat for what I want to do.

    Antoine
  • 22 Oct 2013 20:41
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    Reply # 1419198 on 1418008
    Anonymous member
    This type of hull needs twin rudders because when it heels, it lifts the transom out of the water, and with a single rudder, control is lost and a broach follows. With twin rudders, at least one rudder remains in the water.

    The only type of vane steering that I would try is a central servo pendulum, with the blade trailing aft and the power axis tilted up by about 10 or 20 degrees. This is what I use on Tystie; the effect is to stabilise the course, as the pendulum is trying to self-centre all the time, unless the vane is telling it to adjust the course. The only commercial gear that I know of that incorporates this feature is the Windpilot. They also have a good page of advice here. But even their Pacific Light is rather too big for this boat, and so self-build is the best option. 
  • 22 Oct 2013 16:09
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    Reply # 1418964 on 1418008
    Anonymous member
    Regarding wind vanes, here's a decent introduction illustrating the basic principles (even if practical implementations might differ).

    It will be rather complicated to fit a wind vane self-steering system to that small boat with twin rudders. Fitting a servo pendulum between the rudders will be  somewhat tricky (but doable I think) to implement as to not being in the way of them. A trim tab system would require you to build two of them, one for each rudder, with working linkages in between.

    From the looks of it, and assuming you're going to have twin rudders, I'd go with a servo pendulum (which is also generally accepted as the most efficient self-steering system) if you insist on using wind-vane steering instead of an autopilot.

    Another option would be to use a single rudder. I assume the reasons for using double rudders is to a) minimize draft and b) be able to beach it with the skegs supporting the boat. Using a single transom-mounted rudder would suggest using a trim tab system. But considering the boat is designed to be beachable it's not a particularly attractive option as it would complicate the otherwise simple trim tab system (a servo pendulum is basically independent of the rudder).

    It's worth noting that this is mostly armchair knowledge as I've only built a prototype of a servo pendulum gear myself so far, but I think others will agree.
    Last modified: 22 Oct 2013 16:09 | Anonymous member
  • 22 Oct 2013 10:40
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    Reply # 1418815 on 1418008
    Deleted user
    Thanks for the answers. So I will try to continue on this way with a 22sqm sail. I have to check the Arne's Johanna shape.
    Concerning the windvane, I would really like to get rid of maximum of electric stuff.

    Edit : Here is how it looks like for now : Image

    Antoine
    Last modified: 22 Oct 2013 16:05 | Deleted user
  • 21 Oct 2013 16:48
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    Reply # 1418097 on 1418008
    Anonymous member
    1. Any sailing boat can use junk rig, but some are easier to convert than others. This type of hull will develop quite a lot of weather helm as it heels, so it will be important to use the crew as moveable ballast to keep her upright, and to use always the right mount of sail - here the junk rig will help, as it is so easy to reef. I would want to be able to move the sail back and fore across the mast, as I do on Tystie, to help with the helm balance.
    2. The SA/D ratio for 22 m2 in half-load condition is about 17, and I, as a cruising sailor, would be happy with that. A racing/performance sailor may want to add more area, but I think it would be necessary to make the rig as light as possible, using CFRP for spars.
    3. To fit 25 m2, you probably have to go for a high aspect ratio sail, and only using single spans in the sheet. I would stay with 22m2.
    4. This type of hull will surf very fast down the waves, then will go slow in the troughs. This means that the apparent wind will vary a great deal, and so a vane gear will not steer well with the wind aft of the beam. When boats of this type are used in the Mini Transat, for example, I believe they all use electric autopilots.
  • 21 Oct 2013 16:21
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    Reply # 1418067 on 1418008
    Anonymous member

    Hi,

    I can only answar question no 1 as I have the most modern hull with a junkrig on, an X-99.I had no problem with the adaption of the rig, and would say that if it sails like a sailboat, you can fit a junkrig. As I compete with other fast, well maintained bermuda rigged boats, I have a good knowledge about the junkrig versus the bermuda rig. I would only go back to a bermuda rigged boat for racing purposes only. For cruising, day sailing with the family and sheer fun sailing, especially single handed, the junkrig wins hands down. Period.

    Regards

    Ketil  
       " ...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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