Manually hydrofoil on monohull powerboat

Discussion in 'Hydrodynamics and Aerodynamics' started by Sassriverrat, Oct 4, 2017.

  1. PAR
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    PAR Yacht Designer/Builder

    Telescoping foils are as silly as it gets and will be as successful, as similar applications in the aircraft industry. Yesh, it's been tried, but the cost you pay to get them, doesn't translate to more speed, just more weight, which reduces speed. Austen, do yourself a favor and finish 12th grade, work on growing your beard and learning about the things you seem to think, you can garnish for free here.
     
  2. BlueBell
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    BlueBell Ahhhhh...

    Device failure is almost obsolete but system failure could be another matter...

    As far as I know, you'd be pioneering the telescoping aspect so wear-and-tear will be a matter of design.
     
  3. Sassriverrat
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    Sassriverrat Junior Member

    BlueBell- I haven't been able to find much on any retracting foils- thus I didn't pursue it very far. A friend of mine has a BERMUDA 40- the centerboard is very very heavily modified and she's very fast (for her hull) and has done quite well in the international racing circuits. However, she also has her board pulled every few years for wear and tear and she's maintained with precision (and money) that very very few can equate to and much larger boats don't see.


    PAR- such commentary is neither productive nor does it give you significant credibility. I'm sure you're happy insulting people behind the safety of a computer screen. It's kind of humorous really, like listening to all of the "captains" on various forums talk- a six pack or 50 ton or 100 ton is a joke....

    That being said- I usually try to be quite about my resume because I feel action and reputation precede quite nicely. However, since your apparently a keyboard warrior, I'm trying to teach myself about foils from designs and experience. I passed the "12th grade" some years ago, holding the national record for classes completed in a single semester, three nationals in the college sailing, placing at the junior Olympics (once upon a time), I have two bachelors' degrees and a Master's from one of the best research universities in the country, an unlimited tonnage Coast Guard license, and a few ideas that went on to be patented and now implemented in the electronics industry (all from ideas that I had and some rough sketches that electronics gurus were able to perfect). So, you keep being a keyboard warrior and designing a few boats that may sell drawings, I'll keep trying to further my education and invent in my spare time outside of work, and maybe some of the other guys with experience here or ideas can help come up with something that may work or decide that it won't because of xy reasons. My successes in life have come from taking the paths other didn't, not by following the pack.
     
    Toolate likes this.
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    It is notable that lifting boats entirely on to foils is a rarity in powered craft, less so sailboats. That should give some indication of the snags involved. It is no small problem transmitting power from inside the boat, to props well down below amongst the foils. The Boeing Jetfoil is a kind of acknowledgement of that, all the additional underwater drag and mechanical complications of power transmission eliminated.
     
  5. Sassriverrat
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    Sassriverrat Junior Member

    True. And although not perfected, I figured that during most of the time on foils, the props would be pretty darn close to not fully immersed or likely ventilating/cavitating so that's where the concept of surface piercing style props with an immense amount of power would allow the boat to handle well at low speed and be able to get up and fly, yet the engines could be backed down once flying to the desired speed.

    That is a really good point though.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    You have set yourself a very ambitious task with this, I would say a daunting task. It is a highly technical field, and you are juggling with more balls in the air, that you need control of, than to make a more conventional boat "work".
     
  7. PAR
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    PAR Yacht Designer/Builder

    This subject was studied quite indepthly in the 50's and through the early 90's by the US Navy (and other including the Italians, British, Canadians, Russians, etc.) and eventually abandoned, some for obvious and other not so obvious reasons. Boeing would be a good place to start, though the information is available through a number of resources and this would have been found with a quick search. The first of these craft (US Navy) was decommissioned in the late 60's and (if memory serves), is currently in private ownership. My understanding is all the PHM's have been decommissioned, some scrapped, while others in private hands. Most of the issues with these puppies were maintenance related and of course bashing the foils into stuff didn't help their cause either. High speed foil borne craft are inherently problematic. Even with new, high tech materials, controls and maintenance concerns, caused them to eat their budgets, to the point of not being viable as a platform. Props were quickly discarded, as jets came online, which solved many issues, but articulation of the foils proved costly. Simply put, they found you can run a 75' - 125' coastal patrol craft at 50+ knots without foils and their related costs.
     
  8. Sassriverrat
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    Sassriverrat Junior Member

    Both are very true and I agree. Throughout much of my recent studies (past few weeks), I've read hundreds of declassified military, Boeing, and some other models. I've taken measurements off many of the Miami Shipbuilding models and half models that hang in my grandparents' house and read through innumerable family files. All of these readings lead to me decide that I wanted to stay sub 60 knots with foils that, preferably, did not have significant movement. There was particular emphasis in MSC on unreliability with flight controls and to avoid as much as possible but some of that was old technology. However, I've lived with much of the same principle. My love of some speed in conjunction with not wanting to spend incredible amounts of fuel created the ambition for this project. The US Navy does not worry as much about fuel while reliability and performance are too factors and the reliability killed the boats. It's an interesting gamble to say the least.

    I think the two v-foils with a center plane for additional takeoff and some low speed foiling lift might have promise- I'll need to play with it. I think at Christmas I'll look at getting over to the Academy and having a model printed to see characteristics in a tank. Remember- I have the bow already "supported," I only need 80% of the hull weight on this one set of foils
     
  9. DCockey
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    DCockey Senior Member

  10. Sassriverrat
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    Sassriverrat Junior Member

    I've seen the workboat article. Very good piece indeed- and it was what got me started with the rounded bilge issue (although on a monohull)
     
  11. PAR
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    PAR Yacht Designer/Builder

    This is a classic misnomer and not possible. The design needs to reach takeoff speed and low speed takeoff would require huge foils, which kills high speed potential.

    What is the ultimate goal, as less than 50 knot targets are pretty easy to achieve without foils.
     

  12. DCockey
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    DCockey Senior Member

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