12' and Under Trimarans-Ideas and Designs

Discussion in 'Multihulls' started by Doug Lord, Aug 24, 2016.

  1. Skyak
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    Skyak Senior Member

    This design makes the most sense in terms of why you would want a 12 tri
    -easy to sail
    -easy to get to the water
    -minimized storage
    -low drag makes paddling reasonable

    Doug, your MPX12 looks like it could take all your spare time and money and never give you much or any time on the water. Consider these ratios

    time building and setting up/time enjoying it on the water

    $ spent constructing and maintaining/miles traveled on the water * speed

    miles traveled to a destination planed at least a month ahead/miles traveled back and forth in front of it's trailer on days chosen for their weather.

    The banshee concept makes sense for someone that has a cherub and wants to expand it's use to gusty days. The floats are more about keeping ones butt out of the water than contributing righting to increase speed. If don't have a race dingy to start with R. Woods 10' and 14' tris are better designs.
     
  2. Doug Lord
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    Doug Lord Flight Ready

    -----------------------------------
    I think you are probably wrong but we'll never know because I won't be building the MPX-12. If I build anything it will be slightly longer, 8' wide(+retractable foils) and probably lighter with less max SA. And it will foil in a 5 mph breeze ......
     
  3. Skyak
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    Skyak Senior Member

    Well I certainly never expect you to say I am right. I really don't want to be right. I want to put an end to "we will never know". I want to see you with a plan to put your butt in a boat on the water, safely and easily, any time you want.

    What do you think of the three practicality ratios?

    Making a boat slightly longer, 8' wide that will foil in a 5mph breeze would be a great accomplishment and I think it is possible and desirable. I think the best use of lifting foils is to give big boat performance to small boats with small total cost of ownership. Big low speed takeoff foils will have a lower top speed, but by my practicality ratios they do more for a small boat -more high performance sailing (due to more useful weather). The bigger lightly loaded foils might be made from less exotic materials with less stiffness.
     
  4. Doug Lord
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    Doug Lord Flight Ready

  5. Skyak
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    Skyak Senior Member

    I intended the ratios to be a sober look at any boat project. "If I put my resources into this project how will my life be improved?" The sailing outputs might be a bit utilitarian, but that is what a sailboat is for.

    You say they don't apply to the MPX -I think what you mean is they are not flattering, or don't encourage the build. That was kind of my point. You are not building the MPX for any utility or function -you want to build it to prove something. IMHO that is just a bad reason. The best boats are designed and built to make someone the master of their local waters. If the MPX does not do that for you it is better as a nice model, convenient to store and show.

    That still leaves the question, is there a sailboat build that can improve your life?
     
  6. Doug Lord
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    Doug Lord Flight Ready

    ==============
    First of all I don't want to build the MPX 12 now because it doesn't meet my requirements. When I thought I could build it -and handle it- the primary motivation was to enjoy sailing it. Secondary motivation was to illustrate the advantages the foil system had so that others could enjoy a small tri with the same system.
    IF I do build a small tri the number one motivation I would have is to enjoy the unique sailing characteristics the boat would have.
     
  7. redreuben
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    redreuben redreuben

  8. Will Fraser
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    Will Fraser Senior Member

    That Diecipiedi class looks like a lot of fun. It is nice to see multi's and mono's racing together. I am pretty certain that there is a tri in this size somewhere in my future. The borderline suitability of a 10ft tri must be why some mono's still persist in the class. And then there is the Uffa 10 tri with its beamy vaka that seems to be the best of both.

    In a paper by Nigel Irens on motorized slender hulls operating at SL ratios of 2-2.5, he highlights the importance of keeping the D/L ratio below 100. That means an all-up weight of less than 100kg on a 10ft waterline, something that might work for kids but rather unattainable for me at 95kg.
    BUT, that ratio is for a single hull, and if a tri is sailing heeled with the ama taking a good portion of the load, say 50kg, then a 55kg boat (realistic?) puts me and the vaka right on the 100kg limit.

    I compared a few vaka-ama load combinations in Michlet and it appears that a heavily loaded ama has an advantage as hull-speed is surpassed. At certain ama positions (lateral separation from vaka as well as longitudinal stagger) a fair amount of wave cancellation is possible. One particular configuration even out-performed a 12ft tri above 6kts. While stagger might not give best all-round performance, it is nice to know that the opportunity is there to exploit if the overall length is not limited by some class rule. The same benefit might be possible when using staggered 12ft hulls and comparing it to a 14ft tri.

    Here is some drone footage of a recent Diecipiedi race and one can clearly see the asymmetric wakes of the tri's.
     
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  9. Doug Lord
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    Doug Lord Flight Ready

    Will, thanks for the video!
     
  10. redreuben
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    redreuben redreuben

    Nice drone work, spectacular !
     
  11. Doug Lord
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    Doug Lord Flight Ready

    I'm surprised(as I always have been) that there aren't more powered up small tri designs 12' and under. So much more can be done design wise these days with foils and/or foil assist but it just isn't........I wonder why?
     
  12. redreuben
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    redreuben redreuben

    I suspect Doug that given these boats are home built to a class rule that it's simply a matter of KISS.
    Putting in all the work to build a whiz bang foiler and then have no one to sail against, why bother ?
     
  13. Doug Lord
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    Doug Lord Flight Ready

    I wasn't thinking specifically about the 10' class in Italy but about 12' and under tri's everywhere. You should try foiling sometime and the "why bother " would become clear.
     
  14. redreuben
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    redreuben redreuben

    You should build a boat some time and sail it.
    Foiling is awesome, but it's complex, requires very high skill levels and greatly limiting weather windows.
     

  15. Doug Lord
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    Doug Lord Flight Ready

    ===================
    There are foilers where the set up is relatively simple, that anyone who can sail a sunfish can fly, and that can foil from 5-25 knots of wind. Not limiting at all.....
    Small tri's have the potential to be among the easiest of all foilers to fly and most comfortable!
     
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