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John949

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About John949

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    John
  • Last Name
    Millward

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  1. You could but I wouldn't. Ripstop is used for spinnakers because they have to be scunched up and generally mis-handled. Ripstop is a bit stretchy and not entirely windproof. Mylar makes a much better sail but you have to look after it and not crease it.
  2. I can't give you precise details as I don't have this transmitter but I can give you some ideas to research. I don't know about 3 positions on the throttle but most helicopter settings have 2 using something called an 'idle up' switch. This is for setting higher idle speed when using a collective pitch helicopter. You should be able to program this to give a 'less sheeted in' position when the switch is operated. Another (possibly better) way, which will also give you the rudder function, is to use another (unused) channel that is operated by a three position swtich (flap?). If you then use one of the mixers to mix say 5% flap into throttle (or rudder) the switch will then give you -5, 0, +5 on the channel you are mixing into. (if you get the directions right). There are basically two models for using all the swtiches on knobs on a transmitter. 1) Each switch and knob is permanently associated with a function e.g. the flap switch alters the output of the flap servo. You then use the mixers and built in functions (e.g. V tail) to arrange for the switch / stick to affect other outputs. Most simple transmitters work this way. 2) Multiplex and some other transmitters are more flexible in that, for each output channel, you can specify any number of switches / sticks that will affect the output and in what way. You can spot these transmitters as the switches will be labelled things like 'two position switch' or 'three position switch' rather than 'idle up' or 'flap swtich' What they do depends upon how you program the transmitter.
  3. Thanks for clarifying this John. I think I've got it. At point 4 yellow does have an inside overlap but she is still in the process of tacking so mark room doesn't apply. At point 5 she has completed her tack but now green is inside her, so green is entitled to mark room on yellow. The one aspect I'm still a unertain of is whether this is a'seamlike manoeuvre. Almost by definition missing the mark is not a seamlike manoeuvre so just how much room do the other boats have to give. In your diagram above, at position 5, yellow and red are almost pointing at each other. Just how much can red assume about yellow's future course and if there is contact is red at fault for not giving enough room or is yellow at fault for not performing a seamanlike manoeuvre? I think red should try her hardest to give yellow room but could protest yellow if she believed yellow took her way wide of the mark. Is that right? My understanding (and it;s written in the rules) is that you should avoid collisions if at all possible i.e. avoid the collision first and then protest if you think you've been wronged. I'm new to radio sailing and I'm rather disappointed about how much contact there is. Sure it's difficult to judge distances and angles at times but doesn't that mean you should take less risk? Nine times out of ten it's faster to avoid the collision, even if you're in the right, rather than get tangled up with another boat. When I used to sail dinghies it was the norm to go through an entire regatta without hitting anybody. With radio sailing it seems that at times I struggle to get through a race wihout some contact. I've had a play with boat scenario and it does draw pretty diagrams. Not the most intuitive interface. They key is to understand that the inset modes work like toggles - you have to press the button again to stop it drawing more marks / boats. Pressing delete with nothing selected seems to close the program without warning or saving anything - not an endearing feature!
  4. John, Thanks for the reply. I would have drawn a diagram if I could have drawn as pretty a one as you have: what did you use to draw it? Yes your diagram captures the incident though it was a bit more spread out. Green went further past the mark before returning and yellow did a wide in close out rounding. I'm still not sure about some aspects of the downwind case so I'll have another think about it and maybe draw some diagrams.
  5. If you accidentally sail the wrong side of a mark, what rights do you have when returning to sail the right side of it? A case ocurred the other day where a boat returning to sail the right side came into conflict with a boat that had correctly rounded the mark. The boats were on the same tack and the returning boat was to leeward and wanted to luff the other boat above her proper course in order to sail round the mark. Looking at Rule 23.2 I believe it rests on whether you believe the returning boat is sailing her proper course when she is returning to the mark. If she is sailing her proper course then Rule 11 applies and the windward boat must keep clear. If she is deemed not to be sailing her proper course then it gets a bit murky with the new wording of rule 23.2 as what does 'reasonably practicable mean' In this case the returning boat would have had to gybe round about 270 degrees in order to pass behind the other boat. In a similay vein, what about mark room if you accidentally sail inside a downwind mark and tack to go back and round it correctly? Obviously you have to keep clear while tacking but once you have completed the tack, are you still entitled to mark room from boats which were clear astern when you entered the zone (and you haven't left it)? There is obviously an argument that if you've made a mistake then you shouldn't interfere with someone who hasn't, but I can't see anything in the rules that limits your rights. I also belive that the definition of proper course is the fastest route from where you are now to the next mark. Whether or not you took the fastest route to get to that point is not relevant. Would someone like to explain to me why I'm wrong?
  6. Your method sounds right but it is easy to check if you have got them right. The straight line distances from the half height point to the head and clew should be the same similarly the distances between the 1/4 point and the head and 1/2 point. Ditto 3/4 point and 1/2 height / clew. The 1992 version of the rules had a useful diagram.
  7. I was thinking of full size racing where ther is no requirement to call out sail numbers but it is often done but perhaps shouldn't be.
  8. Nearest common occurence would be the RO calling out numbers of any boats over the line at the start. This is often covered in local sailing instructions but could be considered outside assistance according to the letter of the law.
  9. APPROXIMATELY 660, you have to make the gauge if you want to be sure. My 10R and M fins are about the same length. I thought about making them interchangeable as the 10R is 400g heavier but don't want to start an arms race for club level racing. It may work for you but most people would suggest that a dual rated boat would suffer against a real 10R when the wind gets up. The overhangs increase the waterline length as the boat heels / starts making a significant bow wave and the forward one helps with nosediving allowing a bigger rig to be carried in a given wind strength.
  10. The rules give the dimensions of the gauage. The max length of the fin (to the bottom of the bulb is approx 660 mm from hull surface.
  11. Years ago (when I sailed high performance dinghies) there was a politically incorrect joke about someone froma certain part of Great Britain sending his mast back to Proctor's to have some pre-bend put in it. The joke being that pre-bend wasn't about putting a static bend in the mast but using the ring tension and standing rig set-uo to bend it according to the wind strength - under no load the mast is still straight. This is not the first time I've heard of IOMs using masts that have a static bend. I really don't see the point in this. If you need to bend the mast that much to get a good sail shape then I would think that the sail has been made with too much luff round.
  12. On the subject of soft sails: This is a terrible definition. What does flat mean in this context? One can fold something over so that the top surfaces are parallel (into a U shape) but still leave quite a big gap between the two surfaces, is this flat? Surely creasing is damage (local yeilding for any metallugists). How is a measurer supposed to determine if the material has been damaged if visible changes to the material are allowed but invisible ones (e.g. microscopic cracks) aren't. Just to put the tin hat on it, what does 'ply' mean in the contect of a hetrogenous material like mylar film or a plastic batten material? If the material doesn't have ply's then, as written, the material can break and still pass the letter of this test. Sorry I'll shut up now.
  13. Sorry to bang on about this but a sail thickness rule will not stop fully battened rigs or indeed other areas of local stiffening. If you didn't like my appeal to the science of measuring the wrong parameter, here's a guide on how to make a fully battened rig with a sail thickness rule in place. The most simple rule would be ' The sail thickness shall not be greater than X'. Fair enough, but does this apply to seams? If it doesn't, then one simply creates seams wherever one wants to create stiffening and 'hides' a piece of stiffening material in the seam. If it does, then what is the value of X? If it is an actual value then it has to be large enough for two layers of the thickest sail material that will be allowed plus a layer of double sided tape or whatever to join the sail. So if I use relatively thin material thin material then I have plenty of spare width to include some stiffening material as well. I can see a market opportunity in really thick stiff double sided tape. Something like 'The seams shall be no thicker than twice the thickness of the thinest material plus X' where X is a reasonable width for double sided tape. This is better. but what about stitched seams? The minimum thickness now has to allow for two thicknesses of material, plus the double sided tape, plus two thicknesses of the thread. Sails are normally sown with a swing stitch so there must be an allowable width of stitching; so instead of using a swing stitch, sew two parallel lines of straight stitch and fill the gap with the batten material. And so it goes on. There are also issues with scrim sails and sails made of two different thicknesses of material (perfectly legal at present) which give yet more scope for producing local stiffening and still meeting any thickness rule. A scrim sail made with 'stripes' of wider, stiffer 'thread' material looks interesting. Now you may be thinking that some of my suggestions break other rules that already exist, but that is the whole point of the argument. If we already have rules that prevent local stiffening then we don't need an additional rule. If we don't have such rules then a sail thickness rule doesn't prevent local stiffening. My contention is therefore that a sail thickness rule is either redundant or ineffective and therefore should not be considered. P.S. I made a jib this afternoon and used 'finger style patches to reinforce the tack and the clew. Quite by chance, as the jib was quite narrow, the patches actually overlapped slightly (on opposite sides of the sail) so I accidentally created a sail with full width additional stiffening across the foot. Is this legal? If you think it shouldn't be then how could you write a sail thickness rule that prvented it?
  14. Brad makes an interesting statement which is worth considering in more detail: Marbleheads (and As) are not one designs so change is supposed to happen slowly over time. Marblehead design has changed beyond recognition over the years with the result that (most) boats over 15? years old are totally uncompetitive against modern designs. Allowing change lets the class evolve and remain viable in performance terms against current designs. The price you pay for this is that older designs are not competitive, so older (and cheap) 'beginner boats' are not really worthwhile and attracting new sailors to the class becomes difficult i.e. expensive. What is needed is evolution not revolution so that existing boats / designs are not suddenly put at a disadvantage. As an example, suppose the rule on battens was removed and someone developed a fully battened sail that was significantly faster in high winds, say. Then every serious Marblehead racer would have to go a buy a new fully battened sail. This is not what we want to happen. In a development class the rules are used to prevent development in an unwanted direction such as cost (e.g. banning gold keels) and practicality (e.g. mast height). If the above premise is accepted then the rules (concerning the design of boats) should change for one of two (and only two) reasons: 1) To ban a development that has been shown to be a significant advantage, but is unwarranted for reasons of cost, practicability, safety or accessability. 2) To allow a previously banned development that would now reduce cost or increase practicability, safety or accessability. An example of the latter might be 'First Person Video' which could become so cheap as to not be a cost factor and may encourage more people to take up the sport. Applying these rules suggest that the batten rule should not be changed unless and until someone demonstrates that there is a significant advantage to be gained by 'bending' it AND we, as a class, decide that there are good reasons for NOT allowing it.
  15. I don't think it's the thickness of a sail that's the issue, it's the flexibility of the material that matters. Of course thickness is much easier to measure but it's hard to come up with a good rule that is based on measuring the wrong parameter. If rule changes are being considered then we should also look at the term 'soft sail'. From an engineering standpoint, softness (cf hardness) is the resistance of the material to compression, not how easily it bends. For example, sponge rubber is soft, diamond is hard. If we do want to limit the stiffness of sails then the rule should state what the maximum bending stiffness should be. Many years ago (40 odd?) a read an article on the development of padded sails i.e. two sails with a thin layer of shaped foam between them. I don't think the idea worked but it is interesting to consider whether such a sail could be described as soft, it would certainly be described as thick. It's also intersting to note tht the idea has re-surfaced (in a slightly different form) on the current AC75s.
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