pilot

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About pilot

  • Rank
    Anarchist

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  • Location
    Tallinn
  • Interests
    Sailing, gliding

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  1. pilot

    Vendee Globe 2020

    I think there was something else broken beside the rudder because he had do disconnect it to restore the control. Otherwise I imagine that fixing it (whatever was left of the rudder) in the upper position would be enough. And I think he would not gave up that easy just because continuing meant swapping the single rudder too often. HB has a very long rod-system and both sides are connected inside the cockpit. I think this is the place where it was disconnected because the rod system was broken and jammed. It is not hard to imagine what the fishing-net does if it tangles with one end around the rudder - it spins it with quite a huge torque.
  2. pilot

    Vendee Globe 2020

    Actually only one degree of freedom. How the kick-up system has to work is not specified. Some key points from the rule book that prevents it to be used as horizontal stabilizer.
  3. pilot

    Vendee Globe 2020

    Ok, lets assume that the keel bulb dug into soft whale meat while the bow was cutting into the next wave. Can one distinguish the difference if the boat is folding at the same time? I mean the speed and pitching rotation is absorbed by folding deformations and there is no loud bang that you are expecting during a collision. Or actually you have to look it in this way that usually the damage is avoided because the bow bounces up while going into the wave. But this time the keel was holding it down and the inertia was burring the bow more into the wave.
  4. pilot

    Vendee Globe 2020

    After reading Sam's report regarding damages I can't help thinking that Kevin hit something as well. Not an UFO like Sam. Rather a submerged object with the lower part of the keel. If you do it while flying it can crate quite a punishable pitching motion. I think they didn't consider that in their calculations and simulations.
  5. pilot

    Vendee Globe 2020

    Actually there was one modification in OD parts that was necessary for foilers - the engine coolling water goes through the keel fin now. So, you can't say that they are not evolving.
  6. pilot

    Vendee Globe 2020

    Here is a lot of confusion around terms. To avoid the confusion we need to look at this in historic aspect: EPIRB - (Emergency Position Indicating Radio Beacon) are detected by GOSPAS-SARSAT (over 406MHz). Historically these didn't have GPS and the location was calculated by measuring the doppler effect. The important part is that their message carries the identification of the ship (MMSI) so that the flag country could coordinate the rescue. These used to have homing transmitter (on 121.5 MHz) for SAR as the doppler effect is not accurate enough and can give hours of delay until enough satellites fly over. After GPS was more widely accepted then the homing transmitter was not needed any more. PLB - (Personal Locator Beacon) works in the same principle as EPIRB but without the ship identification. The aim is to make it small enough so it can be carried by a person all time. It can be used on land as well. There are strict rules how PLBs are sold as the serial number is dependent of the country who will coordinate the rescue. The weak point compared to proper EPIRB is the battery size. MOB devices - usually SART AIS or DSC devices. These were developed much later than the PLB. So don't mix it, this is confusing! There is still no standard agreed and most of the plotters don't show any alert if they receive coordinates over AIS or DSC from such kind of devices. AIS can be used for marking buoys or fishing nets in similar way. I had questions - what did Kevin actually use and was it helpful? Did he deploy his PLB or he actually carried a spare EPRB? Main one should be automatically deployable. We know that he had SART AIS beacon but was it helpful. From one of the interviews I read that he thought that Jean found him so quickly first time because of that. But why had he relay on visual search on second time? Does Jean use the AIS receiver at all? And one interesting thought - satellites are capable of tracking AIS nowadays. Can they pick up SART AIS as well? Or this is technically too challenging as the signal is much weaker?
  7. pilot

    Vendee Globe 2020

    I have some burning questions (like always while reading this kind of rescue stories) - what were the actual devices that proved to be useful or what could have been useful? Was this really an EPIRB that gave up the position of the life-raft or it was actually a PLB attached to the life-jacket? Or they have EPIRB attached to the life-raft? If Kevin had an AIS beacon, why didn't Jean use his AIS receiver to track the position? In the end the position given by CROSS was only 1.5 miles off but he still had to conduct visual search. These devices should have range from 2 to 8 miles depending of the model and conditions.
  8. pilot

    Vendee Globe 2020

    He assumes monolithic, but nice to see someone putting in the effort. The central longitudinal bulkhead with cutouts (beam as he said) is definitely quite thin but I am sure that it has thin aramid core in it. It would be too heavy to make that big structure without core. And I assume that this is the main reason why it failed (mostly on the left side) - it is too rigid on side ways. I think the key part in this failure is the right longitudinal beam that was repaired and supported first. He considered these not to play any role in the structure and left those out from analyze. You cant expect a cyclist to understand the importance of beams on the flat skin. I assume that these cracks developed due to deformations in thin unsupported skin. Slamming causes dimples (under the broken beam) and this is pulling the skin causing the central to bend on lower part. Cracks developed over the time from the cutout where the capping failed to the corners. If it were compression force below then I expect to see capping to fail in the middle not in corners.
  9. pilot

    Vendee Globe 2020

    After a second though over the watertight bulkhead - it might not suffer the same fate to the central one. Central has cutout areas from where these cracks started to develop. This is meant to stand longitudinal compression forces not perpendicular bending forces. But this transverse bulkhead does not have weak-points that close to the hull.
  10. pilot

    Vendee Globe 2020

    No, the damaged longitudinal beam was on the right side, so it had to be on Port tack. These beams are located in the middle of the flat area. So when it does not support the area, the water pressure will flex the surface inward during slamming and will create a fold like dimple (together with the rest of the beam). That will pull the skin toward the dimple. And that's what created these cracks on the left side of the central. This beam might been broken already before start but was missed during the final inspection. Or it is really a design mistake. It looks like there is a transition form ticker beam to the thinner that goes through the next bulkhead. Probably this transition point gave up. If the thinner beam would not go through the bulkhead and the transition point would be inside it, we would see similar cracks behind the bulkhead as well.
  11. pilot

    Vendee Globe 2020

    These cracks in the central longitudinal bulkhead, that he presented as the damage, are only some stress cracks caused by the skin below moving to the right on each slamming bounce. I assume it happened over the long period and there is no such cracks on the right side of the central. But the real damage was in the right longitudinal beam that is seen under compression and fixed by some bolts. This allowed the skin to flex in and by doing that it was pulling the central to the right. So I agree. The major damage is fixed and he will resume racing after the latest position update today. The central is more cosmetic and better to fix while headsails are under load as this will compress the upper part of central bulkhead and pull the skin below. This will tighten the cracks closed and these can be laminated over.
  12. pilot

    New Hugo Boss Spotted

    The last generation IMOCAs are a lot more unstable without keel than previous generations were. At least HB and Charal that share the same hull design. This is because foils start to work so early that it is wise to optimize the hull to have less wet surface in displacement mode. This means hulls are narrower and more round. This is pointed out in this video as well:
  13. pilot

    New Hugo Boss Spotted

    A new virtual tour is added into hub: https://www.alexthomsonracing.com/the-hub/internal-360-tour/
  14. pilot

    New Hugo Boss Spotted

    These pictures and a lot more is available here: https://www.alexthomsonracing.com/the-hub/gallery/