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      Abbreviated rules   07/28/2017

      Underdawg did an excellent job of explaining the rules.  Here's the simplified version: Don't insinuate Pedo.  Warning and or timeout for a first offense.  PermaFlick for any subsequent offenses Don't out members.  See above for penalties.  Caveat:  if you have ever used your own real name or personal information here on the forums since, like, ever - it doesn't count and you are fair game. If you see spam posts, report it to the mods.  We do not hang out in every thread 24/7 If you see any of the above, report it to the mods by hitting the Report button in the offending post.   We do not take action for foul language, off-subject content, or abusive behavior unless it escalates to persistent stalking.  There may be times that we might warn someone or flick someone for something particularly egregious.  There is no standard, we will know it when we see it.  If you continually report things that do not fall into rules #1 or 2 above, you may very well get a timeout yourself for annoying the Mods with repeated whining.  Use your best judgement. Warnings, timeouts, suspensions and flicks are arbitrary and capricious.  Deal with it.  Welcome to anarchy.   If you are a newbie, there are unwritten rules to adhere to.  They will be explained to you soon enough.  

jetboy

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About jetboy

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  1. Thanks for the suggestions! I found a workable solution for now. I ended up making the outer parts clamp. They clamp down really well and I made the straps out of 1" x 1/8" stainless, so they're really strong. Once the outer tubes are released the system slides pretty well with just a little car wax to lubricate it. I do still want to move to a folding mechanism just for ease of assembly and coolness factor, but for now it works. I've timed it from parking to water in around 30 minutes. I'd like to have it at 15. Over 20 minutes of the time is for folding out and assembling the trampolines. Here's a picture of one of the clamps. I think the whole system is way overbuilt as a result of the aluminum tubes I have available off the shelf.
  2. Foiling question - (I know...)

    A hang glider may position the COG below the center of lift. I don't know how one might accomplish that with a sailboat on foils. The distance between the foils is related to the static stability. Within the very narrow range of pitch that a typical foiling cat is statically stable, the feedback mechanisms struggle. The further they are apart the more stable the boat will be. And the greater the effect of the forces to remain in equilibrium.
  3. Foiling question - (I know...)

    Many new generation fighter jets have the wing equivalent of a shoal keel. I suspect it is primarily a function of slipstream. The rear wings are effected by the slipstream of the front wings in air. Water at the speed of sailboats doesn't have the same properties as air. Surely you can still drive a forklift with 49% of the weight ahead of the front wheels. That's basically what we're doing with a typical foiling sailboat. It's just not very stable. I suspect it may be possible that stability will expand the use of full foiling beyond the tightrope balancing act that limits its use cruising boats. The additional weight of the foils is basically meaningless on a cruising cat. I'd guess the additional weight of structure is significant though. But I really don't know having not done any modeling. I suspect you should pick up an aero textbook. Fighter jets have advanced control systems, well beyond any sailboat, including AC level tech. They run negative static margin, i.e negative stability. Thus, they are inherently unstable, and rely entirely on the computer to fly. Their wing position has very very little to do with anything hydrofoil related. More to do with Mach effects and being able to efficiently maneuver at a high range of speeds, from 100 kts to Mach ~2. https://en.wikipedia.org/wiki/Area_rule; they can operate with very low tail volume coefficients, and relatively large, efficient wings (with many complex features such as flaps and leading edge slats to allow for high CLmax's and thus low speed flight, while relying on supercritical airfoils for high speed flight) because the computer is keeping the system happy with control surface inputs (of which there are many, many more than we have available on modern hydrofoiling sailboats). Sailboats generally don't have the advantage of modern closed loop fly by wire digital control systems. They must operate in statically stable configurations, ala your typical GA aircraft (alos note: very few of those running around with canard configurations), or only the worlds best sailors would have any chance of sailing them! I don't think airplanes offer much in terms of analogous design - especially for the part below the waterline. That was kinda the point. Having 2 pairs of wings that both provide lift is difficult because they are not independent. The rear set of wings will be significantly effected by the front. Anyway - the same issues do not apply to foils. Operation at a boundary between water and air offers a unique opportunity for dynamic lift with fixed foils. The problem I'm thinking about is the failure of basically every common foiling boat to offer stability and most importantly there are very few that can be sailed with low effort AND low risk of pitchpole. Moving the foils to the outer limits does require that all 4 provide vertical and horizontal lift. it should offer the benefit of eliminating the need for complex pitch control. Possibly even eliminating any active pitch control.
  4. Foiling question - (I know...)

    Many new generation fighter jets have the wing equivalent of a shoal keel. I suspect it is primarily a function of slipstream. The rear wings are effected by the slipstream of the front wings in air. Water at the speed of sailboats doesn't have the same properties as air. Surely you can still drive a forklift with 49% of the weight ahead of the front wheels. That's basically what we're doing with a typical foiling sailboat. It's just not very stable. I suspect it may be possible that stability will expand the use of full foiling beyond the tightrope balancing act that limits its use cruising boats. The additional weight of the foils is basically meaningless on a cruising cat. I'd guess the additional weight of structure is significant though. But I really don't know having not done any modeling.
  5. Foiling question - (I know...)

    So would you also want your front tires near the center of your car? I think the same reasoning applies equally to both situations. It seems that the ideal scenario would be 4 foils at each corner that all steer and provide both lateral and vertical lift. The benefit should be a dramatic improvement in stability. Mechanically it would be quite difficult to have 4 foils steering together efficiently, but it's not impossible.
  6. This may seem really simple - but why are foils typically centered in the same location as traditional centerboards. Instead of using essentially only the center foils for vertical lift and the rudders for tilt control, why not move the foils out to the outer limits? There's a reason we don't drive around unicycles. The stability of using foils at the corners and relying on the rudders or rear foils for the half of the vertical lift. I recognize that this wouldn't be ideal for non-foiling situations. Help me understand why it's not done this way for pure foiling type boats.
  7. I hate to be the bearer or bad news, but very few buyers really care much about going as fast as possible. I don't drive a Z07 to work. I don't even own a sports car anymore. What's fun for 20 minutes isn't always fun for 5 hours. That's what separates what I consider the beach toys (kite boards, windsurfers, and most beach cats) from the small trimarans. If the longest sail you'll normally go out for is an hour or less, sure - foil away. If you want to go sail for a longer day, bring lunch, have a few friends along, anchor and swim, etc. You don't want to use a beach toy. Sure there's some overlap in size, but I suspect there's not a lot of overlap in use. A foiling 18' trimaran would be a beach toy category boat. It surely would be fun - for 20 minutes. I don't think it would be fun for 5 hours.
  8. If the tri can fly the main hull, the amas of the equivalent cat needn't be any heavier than the tri's amas, so the cat can match the inertial characteristics of the tri by adding central ballast, or go faster without it and have lighter amas too. The further the crew can get from the foils, the more RM you have, so you definitely want the foils under the ama. Where a central foil might provide a gain though is where it is deeper than the ama foils and can generate downforce - that can handle a bigger rig while reducing the danger of the downforce-generating foil from popping out of the water due to wave troughs, but this could be done on a cat just as well as a tri and with less weight overall (and you'd only deploy it in strong winds when you need the downforce, and perhaps in light winds where you want more lift to take off in light winds). It depends on how much structure of the floats you're relying on. But in general I agree. The reality is that the scenario of flying the center hull is extremely rare in any trimaran. I've never seen it done for more than brief periods. Additionally with a trimaran the center hull provides additional buoyancy when the ama submerges. A cat has no such ability. For example a trimaran could very well use two amas that are maybe only 10% greater buoyancy than the total boat, still fly the center hull, and be safe and stable while flying on an ama that's 90+% submerged. That's not a realistic option for a cat. A cat generally must have around 3 times the boat's weight of buoyancy in each float. In most cases I think the weight at the extremes is preferable. It will slow most motions and resists gusts better. It will make tacking more difficult as well as righting more difficult. The problem with offset foils from the center of effort is that they are only optimally efficient on one point of sail. On all others they are not optimally located and the sail balance changes leading to sub-optimal sail trim to compensate for the unbalanced center of effort of the sails to the foil. With a cat that's 8' wide - no problem. With a 16' beam it starts to become more and more of an issue. There's a significant offset between a close reach and a broad reach. My trimaran has Nacra hulls and I left the dagger slots and rudder hardware. So I can mix and match and my experience is that a center hull foil pair is better in every scenario except flying the center hull, which practically never happens.
  9. While the net RM may be the same with a cat or tri of similar weight, the motion will not. Moving the weight to the outer edges of the boat will result in greater inertial resistance to motion. Whether that's good or bad depends on what you're attempting to accomplish. Also, having the foils in the center hull will have some inherent benefits as compared to having them separated by some distance from the center of effort of the sails. I don't think it's significant, but there is some small benefit there.
  10. Peter, I think it depends on the size of the amas more than anything else. I know for a fact that an 18' tri with low buoyancy amas can be built very close to the cost of an F 18 cat-no doubt about it. I would argue that an 18' tri of similar materials and craftsmanship would likely cost more than a cat. The cost difference being in the complexity of the center hull, and the folding mechanism. Not the floats. The materials are a small portion of the overall cost. If you use a centerboard/dagger and rudder on the center hull, you've eliminated a rudder assembly and a daggerboard along with all of the manufacturing that goes into putting them in the hulls. So you have some savings there. The main hull is a LOT more complex though on most trimarans. My center hull has IIRC 5 bulkheads, a cabin, seats with underseat storage, a complex internal structure to support the higher loading of the beams, and a lot more volume than any beach cat hull would have. I don't think the savings on hardware and manufacturing of the amas will makeup for the complexity of center hull if it's anything like mine with a cuddy cabin and more complex internal structure. I also have things like a self draining anchor locker. Most beach cats are just two floats with minimal manufacturing complexity. That said - I'm confident a trimaran could be manufactured and sold at a much lower price than most we see. I think the Astus 16.5 is a perfect example and I believe that boat could be scaled up in length to 18-19' with limited additional expense.
  11. From my experience, from someone who's had both - I'll take a trimaran every time as personal boat. There are a lot of reasons, but primarily the versatility. Trimarans of similar size will go fast and go slow well. I really couldn't care less if I was faster than a beach cat. Typically I can outrun them - especially to wind, but a fast cat on a beam reach in light wind often will leave me behind. What I like about a trimaran is the comfort of a regular cockpit when I want it, dry sailing when I want to, ability to take 6 people sailing with a cooler of beer. And still have the ability to get wet, go fast, hit high teens speed, and still park the boat in my garage. There are no beach cats that have the range of use that an 18-20' trimaran offers. I suspect the speed has a lot to do with the beam and the feeling of security it gives. My 18' tri has a 15' beam. It rarely ever feels unsafe or unstable. As it heels when I push it hard it's a slow controlled motion. I think the result is the ability to push harder because it's easy to control as you approach the limit.
  12. WTF is up with "The Wall"?

    You can admit it was effective even if you don't like the purpose. Everyone by now should recognize this. There were many reasons it failed, the primary one being that it was a government built wall to keep the citizens IN and eventually the citizens overcame the government to get OUT. Our wall will be the reverse where the keeper of the wall will have the incentive to maintain it. And with luck it will be completely useless in 28 years. By then we might have a complete immigration reform and almost certainly will have electronic tracking of every single individual sufficient to eliminate the need for the wall. As of today we have neither. In a perfect world Mexico's own economy will boom to the level that its citizens have great opportunity at home and don't want to come to the USA for work. The European walls are quite long as well.They are not a substitute for boarder security. They are a physical barrier that allows fewer guards to enforce larger areas. Of course we *could* enforce the entire boarder with shoulder to shoulder security. Just like I could enforce my property boundary with 24 hour security. Or plchacker could keep his horses in with round the clock supervision. But smart people use tools to reduce labor. A fence is nothing more. It's a tool to reduce labor. And it works Shit, we've moved from voter ID to "Complete Electronic Tracking" So - are we going to all have the little "find your pet" microchips embedded in our person? Fuck you guys like big gov't. I'm not passing a judgment on it. Just saying that IMO it's a near 100% certainty that in 30 years every single person will be trackable in real time.
  13. WTF is up with "The Wall"?

    You can admit it was effective even if you don't like the purpose. Everyone by now should recognize this. There were many reasons it failed, the primary one being that it was a government built wall to keep the citizens IN and eventually the citizens overcame the government to get OUT. Our wall will be the reverse where the keeper of the wall will have the incentive to maintain it. And with luck it will be completely useless in 28 years. By then we might have a complete immigration reform and almost certainly will have electronic tracking of every single individual sufficient to eliminate the need for the wall. As of today we have neither. In a perfect world Mexico's own economy will boom to the level that its citizens have great opportunity at home and don't want to come to the USA for work. The European walls are quite long as well.They are not a substitute for boarder security. They are a physical barrier that allows fewer guards to enforce larger areas. Of course we *could* enforce the entire boarder with shoulder to shoulder security. Just like I could enforce my property boundary with 24 hour security. Or plchacker could keep his horses in with round the clock supervision. But smart people use tools to reduce labor. A fence is nothing more. It's a tool to reduce labor. And it works
  14. WTF is up with "The Wall"?

    Almost all walls for immigration purposes work. The Berlin wall worked exceptionally well. The wall between Hungary and Serbia dropped the rate of illegal immigration from about 10,000 per day to around 10 per day. Turkey, Greece, Bulgaria, and Macedonia all have similar walls that have been similarly effective. There are 65 current boarder walls or fences. You can find any of them you wish. Nearly the entire eastern and southern land boarders of Europe have migrant fences. If Belarus and Latvia connected the boarder fences of Ukraine and Estonia there would be a continuous border fence on the entire eastern front. Similarly if Ukraine built a wall on its border with Moldavia and Romania the entire southern border would be fenced - almost entirely DOUBLE fenced becasue there are border fences south across Macedonia and Bulgaria. These are all new since the Berlin wall... and they're not building them for fun...
  15. WTF is up with "The Wall"?

    Where do you get that stat? It sounds nonsensical. What's the point of having a wall to stop undocumented workers when illegal hirers like Drumpf keep up the demand for undocumented workers and keep hiring illegally? And more, since we obviously don't enforce illegal hiring laws, why not? The benefit of those people to our economy and demographics? A fence with the same law just seems silly to me. As far as "keeping us safe", I've noticed that nobody in this thread has tried to support that one. In 1952 the inner German border was closed and Berlin had mixed control and resulted in a loophole in the immigration rules between east (soviet) and west Germany. Migration was nearly 100% westward out of east germany. The wall was built to keep people IN not OUT. It was effectively a prison wall. During the time it was maintained only about 5,000 people successfully escaped - and roughly 1/3 of those were guards. Prior to the wall being constructed about 500,000 people per DAY crossed the border. Mostly east germans going to work in the west and returning. The net immigration from east to west became a problem for the east. Between 1946 and 1962 roughly 2,500,000 east germans immigrated permanently to the west. In 1961 the rate of migration was about 150,000 per month to the west. Between August of 61 and 1989 the wall was extremely effective. Had it only been 99.99% effective as compared to the immigration rate in July of 1961, the expected immigration over the period would be about 5,040. So while not exactly precise, 99.99% effective is pretty damn close. The Berlin wall was a very bad thing for a lot of reasons, but it was very effective. Anyone who thinks otherwise is simply ignorant. If it wasn't effective - no one would have cared about it. It is hard to stop illegal hiring entirely, but I agree that we need major reforms in our employment law both for workers and employers. In today's world it's pretty damned easy to create a system that works and is reliable to verify citizenship... if you want to. Deporting is like bailing water. It makes no sense to start deporting or even changing the laws without fixing the hole in the boat first. IMO the gaping hole is the border security. The second step is setting up a streamlined work visa process with employer tracking and employer requirements. Third down the line is deporting illegals or working on a permanent status. But securing the border is the first step in any rational process to address the problem. And fences work. And no - you can't have open borders if you also want to maintain our society. It will be the fall of the EU. The tragedy of the commons is as relevant today as it always has been. And it's the reason we generally know that posters are just lying when the say that they have open door policies at their homes/property. It never works. Never has. Never will.