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About mikkom

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  1. I agree that J/70 probably isn't fastest against other similar type boats and in mixed fleet it rarely pays to be slowest boat.
  2. And yet they organise ratings for sportboats that are not intended to operate offshore. I thought that this was context OP asked if J70 is competitive agains other boats with ORC sportboats rules.
  3. @Some.Rando Offshore? Where did that come from? http://www.orcsportsboateuropeans2021.com/
  4. Exactly. I sail in archipelago and we have loads of small wind shadows (like 50-100m). I have small and light boat. So, some heavier designs just roll with momentum through light patches without doing much whereas even if we shift weight trim sails etc. we get stuck. At times that can be a bit frustrating, but I take it as part of game. There are then agains situations when I benefit from light weight (like when we are all stuck and first breath of air comes in). Coming back to your original question I have found that there are sailing techniques that one need to learn to get be
  5. @Black Jack I agree that often conditions can make it easier to perform for different boats. The way you describe experience makes me think that you were able to sail closer to your rating in average than your competitors that had to do much more gear changes as conditions were a bit on the edge for them. Is it maybe bit similar as in slightly more windier conditions on downwind leg it may sometimes be faster to not hoist spinnaker than try to manage it when you are on the edge? All in all isn't this all part of allure of this sport that there are so many parameters that affect our
  6. Now that @Zonker provided one example and rereading @Misbehavin' original post, I might start to see what you are after. We really are interested in upwind performance as that is where most heeling takes place. In short narrow design will heel more than wider design if both have similar sail area. More modern chined hull will in addition get slightly stiffer especially wider angles due to increased speed that creates with hull shape increased stability dynamically (waterplane increases due wave formation). Less heeling means more forward force and thus speed potential is higher.
  7. In short, yes. As @Zonker explained that calculation is part of proper VPP. It is just question if this information have been provided as part of output. Now are you looking for a particular vessel or more in general sense this information? If first, I believe checking if boat has ORC certificate or is one design class (check sailmakers tuning guides if they provide target speeds) might provide good start. I believe ORC provides against small fee performance package that contains basically all information. If interest is more general, maybe some one can provide example?
  8. Have had a bit of exposure to these things. If idea is to utilise wave induce vessel motions to create propulsion, it is important to note that there is certain sweet spot in vessel size due to available wave lengths (and desired speed). So in this sweet spot it can provide quite meaningfull thrust, but outside not so much in practice. There are also some full scale applications out there: https://wavefoil.com/teistin/
  9. Some interesting information regarding this topic by Norwegian insurance company Gard: www.gard.no/web/updates/content/31171690/what-happens-to-containers-lost-overboard-how-long-do-they-float They also mention that they actually do try to recover those lost overboard. Though as we know it is not very easy to locate anything lost at sea (boat, gear, container etc.) As otherwise already noted here some sink immeadiately and some float some time, but eventually sink.
  10. @hariboEnergy approach is interesting, but also results in serious headache.. It is all about which control volume you choose. Large enough control volume and the answer is zero (when consider typical boundary conditions). It really about picking right control volume for the losses you are interested in. For @Sailor Al.suggest to think why there is field continuum mechanics. Thanks anyway, this helped me figure out approach to put another somewhat related discussion in right context.
  11. Hi, Like indicated, I am not any expert and have been just reading how similar type boats/sailplanes are trimmed from various sources. And then done some testing on water. Twist is important and you really need to get speed first and then pointing. I have found that one really shouldn't close leech on main or jib. Both should have twist in all conditions as per my experience and have telltales streaming all the time at top part of sail. I find that jib sheet is never fully sheeted in (block to block). And waves naturally make it a bit more challenging and even more important to
  12. Don't know how much there is first hand experience with 27SE or new 27. And I can't either claim experience with these two models, but I do own 18. So, claiming these boats don't go well upwind is maybe slight misconception. They actually do go quite well for their length and point really well. Challenge is that in order to get full potential out one needs to unlearn ways of sailing more traditional boats. For example mainsail trim and also jib trim. As said, I can only speak from my experience with 18 and I am still learning to sail to my local rating (northern Europe). But I do thi
  13. While I can see this point, I think it has certain feel of luddite. However, what I would put more attention to is how one manages to break two computers in relative short time? Is issue maybe bad quality power feed or pure low cost computers? Could this have been avoided? Even paper charts can get wet or wind rip those to pieces if not used with proper care...
  14. Not really expert either, but have some exposure with container vessels. The 8 is pretty close that you can stack on top of each other. They do actually calculate these, but problem is that those loading containers (this could really anyone) don’t declare correct weight of cargo. So bottom ones might collapse due to weight and hence securing is compromised.. Though at scale seen in this particular case likely related to vessel accelerations being higher than expected. Oh and there is hatch covers between those on deck and the hold - so only visible ones in same stack.
  15. I wonder if Cristopher Pratt will get chance with Charal. It would seem that Jeremie may have too much going on..
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