Minimalistic cruising multihulls

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  • 10 Dec 2018 21:03
    Reply # 6954243 on 6886625

    An explanation might do in covering comments made(in my last posting on this thread), about stayed rigs etc....

    When multihull talk comes around to weight reduction being the pivotal issue, I get nervous and ready to think of monohulls or any way around it....even an unproven proa concept, which might explain why 40years on from starting with the shunting paradigm, am still at it.

    Trimarans and foiling multi's lead the march taking boating in the aerospace direction, which all or mostly use a widened platform for rig support spread.

    So, wider beam dimension plays along with  stayed rig, until it comes to a knockdown or self rescue ability, then we should want less of it, and the Gugeon's G32 shows how less beam can can provide something of benefit, even with a stayed rig.

    For a long time I have wanted to use mast buoyancy to prevent full capsize, and still think a free standing mast could do the trick. But it  probably means reliance on crew body weight for stability as well as recovery.

    This is the precept behind my fixed mast rotating rig design, and stretching the bounds of possibility to work on a heavyish plywood bridge deck catamaran( such as the (Eco6) looks unrealistic....even a stayed rig of the G32 config would likely fail to provide both performance and self rescue function on the Eco 6 , and my experience with catamarans shows that a min beam of 4metres makes good sense on the NZ east coast.

    Last modified: 10 Dec 2018 21:28 | Anonymous member
  • 07 Dec 2018 00:01
    Reply # 6949126 on 6886625

    Sure, having been through all the options, a stayed mast is going to be the lighter way to go.

    Don't mind me, but I'm going there (lightweight styled rig) because it is the most convenient and affordable way to rig my SO (shunting Oceanic) Pahi.

    Having already built double ended hulls of different size, I have more options in terms of lateral trim, and do not  have the same concern about distribution of rigging loads, as a multihull without a central hull to take the mast compression.

  • 06 Dec 2018 23:05
    Reply # 6949090 on 6948791
    Jeremy wrote:

    What I had in mind, was building on the structure to gain more mast bury beneath the bridge deck and using this girder as a pivot/ mounting point for a kick-up stressed ply foil, that doubles as an OB motor bracket.


    There is already a lot of bury in the bridge deck, 900mm at the designed mast position. I have also thought about options such as you suggest, but a maxim to keep in mind in any small multihull is REDUCE WEIGHT. I am already going to be adding weight in a longer cabin top with the aft cabin bulkhead more vertical, and higher bulwarks on either side of the cockpit, so I have to be careful about whatever else I put into the boat.
  • 06 Dec 2018 19:49
    Reply # 6948791 on 6886625

    What I had in mind, was building on the structure to gain more mast bury beneath the bridge deck and using this girder as a pivot/ mounting point for a kick-up stressed ply foil, that doubles as an OB motor bracket.

    Then, I do see your point in keeping it simple, and  a while ago had considered a double hull with daggerboard in one hull and junk rig mast in the other ( just as you mention in youre other thread on the Eco 6 build).

    In researching this option I had tried to get Pete Hill's opinion, but all I managed to come away with was that he did not have much regard for craft that were  too small for his taste, and I figure that twin or biplane rigs make sense when space is not too limited.

    On this 6 metre length craft, however, more innovative thinking might pay off. 

  • 06 Dec 2018 04:51
    Reply # 6947866 on 6947470
    Jeremy Walker wrote:

    Going with the idea of using a wishbone boom and luff spar rig on a free standing mast (as above) on a Kohler Eco 6,  does strike me as a possibility.

    Structural changes to accomodate the mast, might include changing out the daggerboard for a kick-up board on the centre line, and still save most of the accomodation space and layout.

    Only a cursory look at at the Eco 6 material (available on the net) has led to this thinking, but as an alternative to stepping twin masts, I think it would be worth pursuing in depth, because  both the daggerboard's vulnerability to strike damage ( unless a foam packed collision box is included) and the space robbing twin masts are asking for improvement.

    I have thought a lot about daggerboards, and keels, and lift up leeboards on the inside of the hulls, and a central kick up board, and I am coming from 5 decades of sailing and cruising experience. I have decided to go with the forward sloping dagger board as designed. Yes, it could be vulnerable to potential damage, so I will need to be careful when in shallow water, but I think the risk of damage is very minimal. I like simplicity and the dagger board as designed is the most simple solution. Having already built the rudder blades I now know that the stressed plywood daggerboard will be very quick to construct, and the daggerboard case will also be quick and easy to build. There is only one daggerboard which is in the port hull.

    But rig ideas are still very much 'on the drawing board'.

    Last modified: 06 Dec 2018 05:26 | Anonymous member
  • 05 Dec 2018 21:05
    Reply # 6947470 on 6886625

    Going with the idea of using a wishbone boom and luff spar rig on a free standing mast (as above) on a Kohler Eco 6,  does strike me as a possibility.

    Structural changes to accomodate the mast, might include changing out the daggerboard for a kick-up board on the centre line, and still save most of the accomodation space and layout.

    Only a cursory look at at the Eco 6 material (available on the net) has led to this thinking, but as an alternative to stepping twin masts, I think it would be worth pursuing in depth, because  both the daggerboard's vulnerability to strike damage ( unless a foam packed collision box is included) and the space robbing twin masts are asking for improvement.

    Last modified: 05 Dec 2018 21:10 | Anonymous member
  • 04 Dec 2018 04:35
    Reply # 6944438 on 6943895
    Jeremy Walker wrote:

    Drawing is representative of a 16 footer  rather than the 12 f'ter spoken about before, and an extra sail panel has been added along with the extra length.

    Headsail on opposite tack to the main is to prevent obscuring of some lines, and other drawn lines are compromised to avoid clutter.

    Detail is lacking because of scale reduction, so gear (eg steering) is hard to portray, as too, are rigging lines and structural members that need to be added to the wishbone boom.


    I like the concept of this, being someone who would love to find an alternative to the bermudan rig on the little 6 meter catamaran I am building, and having decided that a conventional junk rig probably is not going to work out.
    Last modified: 04 Dec 2018 05:55 | Anonymous member
  • 03 Dec 2018 21:43
    Reply # 6944004 on 6886625

    Thanks for sharing, Jeremy.  I see your artistic skills are still well-honed. Looks like a fascinating project.  Many of us will be watching closely and looking forward to the details in due course.

  • 03 Dec 2018 20:22
    Reply # 6943895 on 6886625

    Body txt is required for posting, so assuming this is included with the pic, here goes.

    Drawing is representative of a 16 footer  rather than the 12 f'ter spoken about before, and an extra sail panel has been added along with the extra length.

    Headsail on opposite tack to the main is to prevent obscuring of some lines, and other drawn lines are compromised to avoid clutter.

    Detail is lacking because of scale reduction, so gear (eg steering) is hard to portray, as too, are rigging lines and structural members that need to be added to the wishbone boom.

    Sorry if this is a meagre showing, but I have warned that anything more meaningful will have to be a 3D structure.

    Last modified: 03 Dec 2018 20:32 | Anonymous member
  • 03 Dec 2018 11:25
    Reply # 6942940 on 6886625

    Jeremy,

    Once you've hit 'reply' or 'quote', you should see at the bottom: 'Attachments' and a box to click on: 'Choose files'. Then you can highlight the file in your computer and click on 'open'. That will put a thumbnail image at the bottom of your posting. Write your text, and 'post'.

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