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MartinRF

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Everything posted by MartinRF

  1. Both boards are fully down throughout this video. That was not perceived as a problem by the helm. When the biggest gusts hit he was not totally happy with rudder response (he is a former Swedish A-cat champion sailing Marström boats -- very skilled but a bit spoilt when it comes to build quality). Afterwards I calculated bow-down and forward tilt and figured that during maximum acceleration even the lee rudder operated almost totally in the wake of the hull: the lowest point of the hull being almost as deep as the tip of the rudder. Hence the plans for new rudder blades. Note that
  2. Yes, bending and tosional stiffness are important, especially if the blades are raked forward: Bending will induce angle-of-attack increasing twist... /Martin
  3. OK, here is what I think may be going on after having looked at the video above. I see you use the same 'geometry trick' I do for balancing transom hung dagger-board rudders. There is really only one mostly aestetic difference: In my case the rudder blade is vertical and the rudder axle is raked. Watch the attached drawing: The left part shows the original design from Tennant. The right-hand side shows what I have had since 25 years or so. I have reduced the distance between the centre of effort and the rudder axle. Your geometry does the exact same thing. The right-hand side also sho
  4. I was spending time at the other end of the speed spectrum today -- had problems reaching five knots. This was possibly the last sail of this season. The temperature had dropped to 3 C when I got back to my apartment. Very nice, calm and quiet as I was all but alone on the water. Tiller gets very light above 18 knots? That's odd I think. Do you know what wing section is used for the rudders? Are they balanced in any way? /Martin
  5. > The failure mode seems to be in the details, such as around reef patches. > This is where the original sail maker shows his worth, as the sail nears the > end of its life. Which is why I mourn the fact that the sailmaker of my last two main sails has closed shop. I had hoped to place an order with him for a new jib... > Sure on dacron Tornado and PT mainsails we used lots and lots of luff tension > to bend the mast, open the leach and move the draft forward. But I'm not > convinced it it effective on bigger boats with radial sails. It is an important tool i
  6. When Kevlar sails were a new thing back in the 1980s I was told they held their shape until they disintegrated. I was not in the echonomical position to test this. Now I have an almost ten year old jib built from a carbon/Kevlar laminate from Contender called Maxx. The material still looks very solid apart from the window which isn't very transparent. Still, ogling the shape in lighter wind I see the draft is not as far forward as it used to be and the leech is hooking. If the wind is up and its sheeted and tuned flat it looks fairly good. (Disclaimer, when the wind is up I don't have
  7. My jib sheet is routed 'on top' from cockpit to cockpit via the jib clew: Forward from the winch to a cheek block on the main beam, then along the top of the beam to a block on the traveler, through a block attached to the clew and down to another block on the traveler etc. The line I am giving a tug in that video is the barberhauler. That one is routed under the trampolines. I need to give it a tug as the traveler track of the jib is straight and the jib is only semi-self-tacking. Simplisticy over function? /Martin PS Nice photo paxfish.
  8. See, Paxfish, I am not the only one doing my own hardware. /Martin (Looks like sail I could have a lot of fun with on my boat.)
  9. I think length = size is a mistake. Sundreamer was, if memroy serves, designed as a very long fortyfooter: Width and sailplan as if she was 12 m long but with 18 m long hulls. ORMA 60s were designed to a rule which limited length, width and rig height but not much else. They were designed for pro sailors and money was not an issue until it became such a big issue it killed the class. Designing them became a desperate pursuit of longitudinal stability, according to Nigel Irens. All information I have indicate the MOD 70 trimarans are much better boats and in most cases actually fast
  10. Me on Ackermann: http://hem.bredband.net/b262106/Boat/acker.html /Martin
  11. Been there done that twice. Once because of stupid underbuild and second time because I hit a rock. That time I missed a race but the boat was back in working order within a week. By the looks of it I don't think you hit something. I think this is a case of too weak. Remove damaged laminate (angle grinder and 40 grit 'paper' comes to mind). Rebuild and make it strong enough. You need a 'bandage' of fibres holding it together between the pin and the sleeve. Idealy you should have fibres forming a figure '8' with the rudder sleeve in one loop and the bolt (pin) in the other loop + fi
  12. Their store locator does not feature Scandinavia or even Europe. I have been told covered lorries are painted using 2-pot polyurethanes like the ones we are used to and you can get any colour you fancy. I will investigate this. /Martin
  13. Easier said than done since that yellow colour is not part of either International's or Hempel's offering any longer. I have some ideas on where and how to get it but some investigation effort is needed. /Martin
  14. Lessons learned: Longboarding isn't quite as intimidating as I thought, but it is a good thing to be patient and not try to do it all in one go. From an Altex video I learned about applying tracer paint onto the undercoat before sanding. This really helped. Keeping the mixed and thinned (20--25% thinner) paint in a bottle and squirting paint into the roller tray as needed to wet the roller ensured consistent viscosity throughout the application. Don't count on weather being cooperative /Martin
  15. I have had really good battens from day one but the first set of sails were undebuilt dacron sails (1986, remember?) and good battens can not save bad sails We found another sailmaker, one who knew what he was doing, who re-cut the main and reinforced its leach and we ended up with a useful if not good sail. /Martin
  16. Perfection was not the goal and I don't like adding weight to my boat so I added almost no filler -- less than 100 g for sure. I sanded until reaching high spots of the laminate and did not fill in lows. I then undid some of the longboarding as I removed the 60 grit paper scratches by machine sanding with finer paper: exposed filler sanded quicker than old paint. Still fairer than before. /Martin
  17. Same here but I have only had one -- an Accord which is 15 years old (Sorry couldn't resist) /Martin
  18. OK, I don't have any photos of the end result but this is the second to last coat in the making. International Perfection with ~20% thinner and at some 8 C. Only the port hull was painted when this photo was shot. The last coat was put on the day after and did not come out this good. Because it was a little warmer? Because it is harder to judge how much you apply when there is no shift in colour or gloss? Because paint flows differently on a sanded surface? Becuase I did not hit the correct viscosity as accurately? Anyaways, it looks OK from even a modest distance -- at least while stil
  19. Work progresses and I may be in the positions to launch next weekend. I do think I finally reached the level of the one boat length rule. Keeping viscosity in check by keeping the paint in a bottle and squirting paint on the foam roller as I went really helped. Some non-timely rain did not help... And that long-term weather forecast actually came true. This weekend has been really nice weather-wise. /Martin
  20. Test painting already done, sort of. The very first square metre or so painted on Saturday came out really nice. This was when I had good thinning accuracy having added a known quantity of thinner to a known ammount of paint. Then I lost track of viscosity and didn't manage to fully compensate for evaporation. Or at least, this is my theory and why I think keeping the thinned paint in a closed bottle and none of it in the roller tray may help. I did keep a lid on the container for the paint but there was always some paint in the roller tray. Temperature between 15 and 20 degrees? I see not
  21. I am having problems wth the boat length rule. First coat of paint went on on Saturday (rain on Sunday) and I am clearly out of practice. Sanding again -- yeah, it's that bad I *think* my problem was I did not control the viscosity well enough but I have a plan for the next coat that I think will make me less dependent on varying evaporation rates (wind, sun...): Keep the properly thinned paint in a big PET bottle. Make small *small* hole in cap and pour paint right on the roller -- keeping nothing in the roller tray. What do you think? /Martin
  22. Line between aft beam and boom: 5 mm Dyneema. The other line is 10 mm polyester double braid. Smaller diameter would also work with gloves. The blocks for the Dyneema line are Harken wire blocks. The blocks under the boom are home made. Here is the moving one: Much lighter than anything I could buy at the time since I engineered it for a relatively low load for 60 mm sheaves. The block attached forward under the boom is somewhat different and based on sheaves from Fredricksen. I don't remember diameter but most likely 60 mm. More photos: /Martin
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