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WetSnail

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Everything posted by WetSnail

  1. I don't see how that makes a difference to stability. Whether you put the lead in the middle or divide it in two and put each half out to the side at the same depth, the centre of gravity will be in the same place. Where it does matter is in rotational inertia. The lead in the bilge keels is farther from the centre of rotation, and so it takes more energy to make the boat roll, which is good. The same goes for roll damping. For the same draft, the bilge keels are farther from the centre of rotation, giving them a better arm for dissipating energy, and moving faster through the water for a give
  2. I noticed. What I don't understand is how that is relevant to the moral issue you raised: 'Why is it not "ok" to consume fuel for pleasure?'
  3. "Free" and "their" are doing a lot of heavy lifting here. When it comes to "free", you may have heard of the maxim "your freedom to swing your fist stops at my nose". If you believe in that definition of freedom, rather than "might is right", you should want to avoid creating externalities, imposing the costs of your choices on others. And that means you should care what others think. Big yachts are externalities made solid. Their owners don't pay for the full costs of the pollution associated with the extraction of the relevant resources and the dumping of the wastes associated with building
  4. Would this kind of thing be worth bothering with? https://flin-solar.com/
  5. There is a Twitter account dedicated mostly to nautical folly, occasionally branching out into other substance-inspired engineering: https://twitter.com/TheDreadShips One of my favourite threads is about the torpedo ram Polyphemus: https://twitter.com/TheDreadShips/status/1144365560551084043
  6. A very convenient rule for a country that is surrounded by countries considered safe. But is it even UK law? Someone stood up in the House of Lords and pointed out that even the Home Office, so dedicated to sending Johnny Foreigner back to where he came from (Russian Oligarchs and money launderers excepted) accepts over 70% of asylum applications from people crossing the channel (https://twitter.com/OliDugmore/status/1464536696138178569). If they were, by definition, economic migrants, that would not be happening. Also, as I understand it, the UK, like the USA, does not accept asylum a
  7. Exactly. Designed by a gifted five year old who wants to circumnavigate Fairyland, and made real by a Womble engineer.
  8. You may be able to adjust for your needs. I defined the lower point on the hull, and two on the beam. I drew a circle around the lower point to define where the outer point on the beam, and the strut between them, would end up after folding. Because you wanted waterstays, I thought I could attach the strut to a dolphin striker on a waterstay, which gave me a bit more freedom in where the outer and lower strut could go, and how long it had to be. I rotated and shifted until the whole thing was reasonably narrow. Then I looked at the two points on the beam, drew the perpendicular bisector b
  9. Very nice. What is the reason for the foot of the yard only going to the forward crossbeam instead of the bow? Is it that you don't need to shift the sail that far forward because you have a big rudder, that you want to load up the rudder to provide lateral resistance, that it is safer for the crew, or some combination of those, or something else entirely?
  10. Would this do? Blue is unfolded, orange is folded, the fat lines are the struts of the folding system (and the dolphin striker on the waterstay). I haven't checked what that would do to shrouds. You'd have to adjust the geometry to take care of that once you know how high up the shrouds attach.
  11. You could make a boat trolley with large wheels, perhaps from a fat bike. Given the size of rocks on your beach, I am not sure even that would work, but much of the coast where I live looks similar, and the solution I have seen is light rail. People lay rails into the water and run a boat trolley on those, possibly with a winch installed in a boat house.
  12. There is a wire going from the end of the windward outrigger into the water. The boat may be stabilised by paravane. I found the listing and there are no pictures of the paravanes. To answer Bull City's question, paravanes are foils on strings, like these: https://www.youtube.com/watch?v=qF4A2Wf2alM https://www.youtube.com/watch?v=sJ9qwAQ_ofQ But the wire seems to pull nearly straight down, so it may be more like what you see here, about 10 minutes in: https://www.youtube.com/watch?v=EYp8eVApLrg
  13. If you cut plywood into strips, stacked them on top of each other and glued, then profiled that, you would have half the wood fibres going parallel to span as before, but the other half would not be parallel to the chord, but perpendicular. Would that turn plywood into a good shear web suitable for covering with laminate?
  14. If you mean let them bend, then let's say you build them out of a low modulus material, meaning they bend enough in light wind without breaking in strong wind. You still have the problem that the more wind there is, the more they bend. That is because each batten is sheeted. It must act as a boom for the panels immediately above and below. That is mostly a feature, because you don't need to control twist by pulling hard on the leech, and that reduces loads on sail, yard, boom, and mast, and that is a big difference to the lug rig. But if you make the battens bendy enough to get a good sha
  15. Don't know. But narrow inflatable kayaks are pretty recent designs, so he most likely used one with a fat tube either side of the paddler, and those are quite beamy and stable. I forgot to mention https://woodenwidget.com/ Their Fliptail folding dinghy and Stasha nesting dinghy are both quite light, being skin on frame boats. So those might also be suitable alternatives if light weight is important to 2airishuman. Of course, if the Chameleon is a favourite design, alternatives may be irrelevant.
  16. Jerome Fitzgerald, in one of his books, swore that the best dinghy is an inflatable kayak. And just yesterday, I watched an introduction into what is available: https://www.youtube.com/watch?v=5U8u_rkNTSY I think they are all lighter than what you think of building, and they pack down smaller.
  17. Hitting the bottom while trying not to broach when sailing in through surf. The more the load is sideways, the more friction there is between rudder blade and rudder head, and the less force there is to trigger the kick up. The rudders are designed for beach cats, so this is very much an expected load case. The moment you ground, the load is no longer limited by how much force the water can exert on the foil.
  18. Bought one recently, but haven't used it yet. Looks good, though. If you have a rudder and head, and just want the rudder to kick up, that cam cleat is a perfectly adequate and much cheaper solution. But I can't build a rudder that stands up to that kind of load: https://www.youtube.com/watch?v=hDeI-SIM7No&feature=emb_rel_end
  19. Thanks for the reply. I can understand issues with twist, assuming beam spacing is limited by needing to sheet to a traveller attached to a beam. What do you mean by sailing balance? The relationship between centres of effort and lateral resistance? I assumed the relationship between mast, front beam and foils would remain the same, no matter where you placed the three, and that would take care of balance. Have I overlooked something? If one designed a boat under the assumption that it always foiled above some threshold speed, would there be any drawback to placing front beam and mas
  20. That link shows a plank across the cockpit with a hole that is the mast partner for the mizzen. In the video, at 0:58, that plank is absent. What is holding up the mizzen? The perhaps 20cm bury you can get under the cockpit sole?
  21. One difference that can be important is time. I was flipped backwards sailing out through surf, had a righting line rigged up that I could have just grabbed from under the hull, but was stuck on first flipping it over the hull. I neglected that the water was only about three meters deep, and the mast was stuck on the bottom. Between the extra load from me leaning on the beam so I could get the line over and the extra time of waves bouncing the mast off the bottom, it broke.
  22. It's a daily calibration of the sensor, says one of the scientists using the data: https://www.youtube.com/watch?v=sDHXSGeov3I
  23. Question from someone who has never foiled: I noticed that in Moths, the distance between the main foil and the elevator on the rudder is a large proportion of boat length, and the rig is fairly far forward, the opposite to A-cats on both counts. Now, in displacement mode, placing the rig farther back reduces nosediving in a cat, but is that still necessary once you foil? Is there something to be gained from separating main foil and rudder by the largest distance that the platform allows to give the foils better control over pitch by increasing the lever arm, and place the rig accordingly?
  24. I started with the rule of thumb that steel should not be loaded to more then 1/5 of its yield strength if you want it to last indefinitely. I looked up some fatigue curves (I don't remember how to upload pictures, and don't see that option in the menu), and found that depends more on the type of steel than I had realised. I cross-checked a book on anchoring, which gives the safe working load of BBB chain as 1/4 of breaking load, and for high tensile chain 1/3 of breaking load. Aluminium doesn't have a fatigue limit. No matter how low the load, aluminium will fatigue, and eventually b
  25. Sorry, I am somewhat interested, but not that interested. My description was of a vector diagram, so it should be possible to translate it into a drawing if it interests you enough. If not, we can just drop it. They are not the ones who say there is a problem, and I am not telling them they have a problem. My reasoning is that the load case is similar, and if there were a fundamental problem, it should show up in boats that routinely experience the load case that worries you, and there are a lot more catamarans than proas, each catamaran spending a lot more time sailing downw
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