hreko

Discussion in 'Boat Design' started by hreko, Sep 14, 2012.

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  1. hreko

    hreko Previous Member

    Some new pictures for the people who find HReko1ooo project interesting :)
     

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  2. bpw
    Joined: May 2012
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    bpw Senior Member

    How do you plan to deal with the loads on the dinghy in a seaway? Most dinghys will not take kindly to being stuffed completely underwater and then lifted by the transom while full.

    What advantage do you see in your design over a catamaran, seems most any cat would meet you SOR and be quite a bit higher performance.
     
  3. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Hey it's a concept --give it a go. The dynamic operation of a machine often results in unforeseen positive qualities that far override any drawbacks. That plus modifications and progression of the design could result in an entirely new and improved type of vessel. Recall it wasn't that long ago the bible was a cods head and mackerels tale.
    However I do disagree "carbon Neutral". For every action there is reaction, manufacturing of the hulls materials, the solar panels, and the limited life batteries and electric motors all inject very dangerous long life chemicals and carbon into the planet's atmosphere. Me thinks there is no free ride only more alchemy for profit and control.

    "A yacht is not defined by the vessel but by the care and love of her owner" ----(The author I can't recall, I was but a much younger man when these words so impressed me) :)
     
  4. El_Guero

    El_Guero Previous Member

    OK, my dear friend from Spain suggested you discuss this design with a naval architect.

    I think my friend, and your friend, was correct.

    Ask about the sponson digging in, because from the angle in the photos, it looks like the the sponson will have a negative angle to the bow when leaned over ....

    Do you really want the bow area to dig in?

    Maybe it won't happen.

    But, get it on the water, and talk with a naval architect ....

    wayne
     
  5. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Seems a little late in the game for major engineering changes with the hull but that sponson does look angled downward to the longitudinal run of the entrance. I'm no engineer but If so, heeled under sail it could "drag" her bow down, increase heel and with a further increase in speed resulting in one of two outcomes, #1 The overall boyancy of the sponson will be enough to counteract, thus it becomes an issue of cycles: Increasing speed/increaing heel /bow plane diving /offset by increased sponson boyancy/ incresed drag reduces speed/ reducing the heel and bow down attitude/resulting in less drag allowing increasing speed to repeat the cycle.#2 Under a stiff breeze or gust the first half of the cycle happens so fast she cartwheels diagonally. OR The engineered boyancy of the sponson has increased the initial stability of the hull verses the sail area to counteract she never heels to the point of initiating the above cycle of events. In this case she could be a sponson water throwing wet speed demon requiring a sharp lookout to reef very early. :D

    A yacht is not defined by the vessel but by the love and care of her owner --
     
  6. hreko

    hreko Previous Member

    There will not be loads on the dinghy (either deck or bow). This fast 40 footer with its wide, full stern, has less than 8000 pounds displacement (no water in bilge keels and favorable longitudinal trim downwind)
    A comparable cat (cc 3500 kg displacement/ 40 feet) is more than twice as wide as HReko 1ooo. Imagine that you have two times higher salary or you always have to pay half price.:)
    HReko 1ooo can recover if capsize without help from aside. Cat cannot. Try to imagine you’re cat in inland waterways of America or Europe. HReko 1ooo with its 8 foot air draft, built in fenders, two azipod electro motors and minor draft is suited for continent and ocean sailing.
     
    Last edited: Oct 13, 2013
  7. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    I can not understand why you compare HReko 1000 with a catamaran. HReko1000 IS A MONO HULL with sponsons. As a mono hull I have not the slightest doubt that it is much heavier than any other vessel of her length.
    Crew will need to work very carefully to avoid breaking solar panels.
    Stream lines of water flow aft can not be worse.
    You know it's very possible that does not meet the stability criterion which states that the angle of maximum GZ should be 25 degrees or higher?
    You know that all the sailboats, after capsizing (releasing the sails), are self righting?. Need not float on the top of the mast, nor external help.
    By the way, what right job at the shipyard. The pity is, in my opinion, what have dedicated their efforts.
    Some people on this forum, long time ago, have warned you about what might happen with this project.
    Cheers and enjoy your design.
     
  8. hreko

    hreko Previous Member


    This boat with substantial initial stability (RM25 is about 4500 kgm) will normally sail with not more than 20 degrees healing. (preferably 15).
    The spnsons will not dig because when boat heals “wide buttocks” reach the water first. Ballast water pumped to the luff tank means shift of 360 kg 2,5 m ( 8 feet) to the stern direction with consequent bow tilt.
    In a few months we will test sea behavior of the “hreko” ( "Žabac V" what means "male frog" in Croatian language)
     
  9. hreko

    hreko Previous Member

    Viking, I read your comment with interest but each boat on stiff breeze or gust behaves as you wrote and why should hreko be exception. I think you're wrong that hreko should earlier reef the sails. Comparing with conventional monohulls of its length hreko has two times higher RM (average) in the range of 0-30 degrees. On the other side he has les sail surface than comparable monohulls. Higher RM and les surface, why earlier reefing?
     
  10. frank smith
    Joined: Oct 2009
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    frank smith Senior Member

    Cool, but seam like a lot to invest on a hunch. Please post on trials.

    FS
     
  11. Skyak
    Joined: Jul 2012
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    Skyak Senior Member

    HREKO,

    Thanks for bringing your very interesting project to this board. Several of the features are things that I have dreamed of designing on a boat of my own and your goal of a fast, self sustaining cruising boat are exactly what I would work to achieve. We have a saying 'his heart is in the right place'. I wish I would have seen this sooner and that I could have pointed out problems and contributed improvements to the project because (unfortunately) I see the problems that others are bringing up. These are valid concerns.

    If I can help you translate, understand, or quantify any of these I would consider it worthwhile.

    For now I think I should point out one major concept

    Hull drag=surface friction+wave drag+eddy drag

    This is an old equation from Skeins. Today all the boat designs only talk about surface area (friction) and hull length (wave) -because they are assuming the hull is smooth and in trim (if it is not, the NA screwed up). Your hull is not smoothed, so they bring out the many problems that can occur. The hull and it's appendages can oppose each other at different heel angles so there is no right trim. The good and bad news is that these eddy losses are harder to define than they are to design out. This is why there are so many negative reactions to your 'sponsons' which are just large water ballast tanks with a hull bump. You credit your design with reduced drag due to increased waterline length, but you do not add the drag of the portions of the main hull transom that are below the waterline vertical.

    Your estimates for performance are more than optimistic. I think this makes the comments extra critical and negative. Your large shifting water ballast is extremely aggressive, possibly dangerous in the absence of any fixed ballast. Even the Open class racers had some deep fixed ballast. I think you should consider leaving the keels as permanent fresh water tanks (maybe place some heavy batteries in the space if they fit, and possibly adding plates on the bottom. The sponsons could be seawater, used to trim or dropped completely when no righting is needed. Wind and waves do not come from only one steady direction. If we do the calculations for heel and trim I think you will see the value and safety of this configuration.

    You have not begun construction on the sail rig have you? Maybe we can do some good by checking it for performance and problems.
     
  12. hreko

    hreko Previous Member

    Maybe you cannot understand because you're not smart enough?. Your Spanish friend likened hreko and catamaran and asked me what are the advantages of this concept compared to catamaran. I just answered him. Smaller width and selfrighting ability.

    Hreko is not conventional monohul with big balls (lead keel)
    She looks a bit strange isn’t it?
    Disengage a little from your way of thinking. Not all sailboats are self-righting. Lot of multihulls are also sailing boats but they are not self righting. Do you get it?

    "HReko1000 IS A MONO HULL with sponsons."
     
    Last edited: Oct 13, 2013
  13. Skyak
    Joined: Jul 2012
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    Skyak Senior Member

    To contribute to hull length the dingy must displace water and take load. Consider the condition of a following wave -a wave that overtakes the boat from the rear. It picks up the boat from the rear first. Whatever the weight of the boat is half of that weight can be applied to the dingy plus force of acceleration (a safety factor). I don't think you want to build the dingy strong enough to lift the main hull so you should consider a compliant attachment for this rare condition.
     
  14. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    You are quite right, bpw was asking about catamarans and also right to say that catamarans are not self righting. I was talking about the mono hull and I made a generalization that can be misinterpreted. Also I have to clarify, for no more mistakes, than what actually happens in sailing monohulls is that, in general, GZ values ​​are positive for angles greater than 90 degrees.
    Also I have to say, maybe you do not understand, that the fact that the RM is higher or lower, does not guarantee anything because what you have to compare for similar boat, is the value of GZ for each angle of heel, for the same displacement.
    Are you thinking about striking out the other boats?. If not, why do you need the foam protection 10 mm thick?
    I sincerely believe that a boat with the cross section 2 is much better than the one of section 1.
     

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  15. hreko

    hreko Previous Member

    Skyak,

    maybe you should go to old web site of Hreko ( www.hreko.com ) to find some more information’s. In the mean time I changed the concept of water ballast. It was fresh water in the first version but do not overlook. Hreko is sailing boat with electrical propulsion (serial hybrid). Electro sailing with no or low wind condition will have a lot of benefits from 700 kg lighter ship. Hreko has inner ballast of about 350 kg batteries, 300 kg generator, electro motor’s and el. equipment, 200 kg fuel and 200 kg water tank. I would not say that big shifting of 350 kg water, which is about 10% of displacement, will have such drastic impact on boat static and dynamic stability behavior. Water ballast takes a part of about 1/4 of overall stability.
    In this moment I am busy with rigging (carbon rigging is too expensive and I decided to do with Al sections). I will appreciate if I get some assistance with mast calculations.
     
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