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About neuronz

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  1. neuronz

    3D printed daggerboard templates?

    Yes, I actually had a template milled similar to what is shown in your lower picture. It worked well, but in my case the profile was very far away from any useful section shape, so I used it mostly to get the rough shape. Afterwards it was normal sanding and filling and checking with the template. It also helped me to have solid leading and trailing edges to use as rails to guide the template. I glued a haved FRP-tube to the leading edge of my profile for this. I suggest to make the template a bit longer chordwise and extend it slightly around the trailing edge.
  2. neuronz

    Best Passing Strategy??

    Boatspeed makes a great tactician.
  3. As far as I know one of the reasons for using an angled board is also a rather large movement of the aerodynamic center of effort between upwind and downwind sail sets. Upwind the COE is more aft and you need the full board area. Downwind with big sails tacked far forward the COE is more forward, but you need less board so it is pulled up to maintain balance
  4. neuronz

    Hakan Södergren 31ft racer

    We also found last year in our 8m boat that when sailing doublehanded aggressive stacking makes a huge difference. In our case it was only two bags, a headsail and two spinnakers, but it was worth about 0.2 - 0.3 knots.
  5. neuronz

    Hakan Södergren 31ft racer

    The hull shape probably lends itself well to waterballast. However, it adds complexity. If I was you I would sail the boat for a season and see how it handles. There are also other options like shortening the rig to its original dimensions and going with a moderate fat head.
  6. neuronz

    Tethers - Quick Release or Not?

    For anyone looking for a lifeline with integrated quick release, I am very happy with this one. KONG lifeline It has new types of lightweight carabiners and the two elastic ends make life easier when not in use. It is a bit cheaper than the comparable spinlock product as Well.
  7. Agreed. The pressure field around the board will cause asymmetric flow around the hull if it operates at zero incidence. It would probably be more precise to say you don't want the hull to generate lift. However, this point will be close to zero leeway. As I said before, reality is a bit more complicated, but sometimes things need to be simplified to explain the idea. I can actually imagine that minimum drag actually occurs when the hull contributes a tiny fraction of the lift, but this would have to be analysed in depth.
  8. This is only applies if there the board twists significantly under load. Assuming an ideal board with a constant cross section you actually get the maximum load at the hull board intersection.
  9. When you don't need lift any board should be raised to reduce drag. The big difference between sailboats and airplanes is that airplanes can vary the lift in their wings and change altitude. In sailboats the lift on the appendages is always equal and opposite to the aerodynamic sideforce. Any manipulation of the section like flaps only changes the angle at which this lift is produced and the drag associated with it. All else being equal the lift is constant.
  10. It depends in the specific section shape. Put simple the more you deviate from the symmetric case, the more lift you get at negative angles of attack.
  11. The benefit of asymmetric boards is mainly that they produce lift at zero angle of attack. This means that you can have your hulls operating at zero angle of attack. This is beneficial since hulls are not very efficient at producing sideforce compared to high aspect daggerboards. The difference between an asymmetric board and a symmetric board angled towards the hull centerline is marginal, they are basically the same thing. It does make sense to lift asymmetric boards with increasing speed since lift is proportional to speed squared, area and angle of attack. As a first approximation the alignment to the hull defines your target angle of attack since you want those to operate in neutral. For a given lift and speed raising the board enables you to adjust the angle of attack of the board to your target as it reduces the area. Reality is a bit more complicated since the board immersion also changes its aspect ratio and therefore induced drag and the leeway angle also affects aerodynamics, but I think you get the point.
  12. neuronz

    Warnemünde, Germany typical conditions?

    From a statistical point of you get the nicest weather (= mostly sunny and stable) in May and June in northern Germany. At some point the sea and air temperatures increase too much and the athmosphere starts to become a bit unstable with a higher chance of rain and thunderstorms. The rule of thumb is that the bad weather starts with Kiel Week which always is the last full week in June. Regarding the sightseeing, as others have said Hamburg and Berlin are both close. You can do both as there is both a motorway and a fast train connection between the two. From Berlin other historic cities in eastern Germany are easily reached. Beyond that distances start to increase somewhat. There are also a few smaller cities with world heritage sites spread along the coast east and west of Warnemünde.
  13. neuronz

    what is it?

    New 52ft Oystercatcher XXXV by Carkeek Design Partners and currently in build at fibre mechanics in the UK.
  14. neuronz

    sanding concave areas

    Thx everyone. I will check if the curvature is constant enough for a custom sanding block. Otherwise we do have small sanding sponges already. Maybe there is something available one or two sizes bigger.
  15. neuronz

    sanding concave areas

    We are currently preparing our deck for a refit. Sanding flat and convex areas has been a breeze so far with a sander and expensive sandpaper. However, the intersections of the coachroof with the sidedeck and the cockpitwalls with the cockpit floor are relatively large concave areas we cannot really use our sander for. Can anyone recommend a good method or tool for this? Preferably not too expensive since we will likely only use it once. Or simple lots of elbow grease?