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Dude

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  1. No Booboo it does'not. I thought as you did too but whatever attachment to the headboard must surely be loading the masthead and sheave pin the same amount. Sure there is extra friction when the rope is moving thru the shackle but when stopped it is all same. As for the shroud base issue. I understand the width/ loading numbers but when practical assessment is considered to a narrow yacht where the beam differences are so small and the dissection angles of attachment of the stays are so minimal there is bugger all difference in compression calcs. In a cat it would count and yea
  2. Correct and I don't think anyone was argueing that point?
  3. Nice JH but there is no boat in that world with a stay angle like you're left picture angle Also this is a silly comparison. To compare correctly you need an opposing red line to make the other stay (that is holding the rig in equilibrium and transferring loadings to compression on the mast) that all boats have on every mast except a back stay on a fractional rig. Close but no cigar.
  4. Totally agree WT. But we weer talking NZ club racing boats and lamp posts. I don't agree that more width and smaller sections is the right solution. Its just the current thinking and where all the money and energy has gone. If they spent as much time and effort on cat rigs then...who knows. ETNZ would be dog tucker with current thin stick many stays thinking. There is a lot to be said for large rotating mast sections with minimal Stays or no stays. Greg Elliot played with this and many fast cat boats in America swear by it. Compression is the enemy. Cat boats suffer no i
  5. Just let him do it. It's good business for the spar makers. Do what?.
  6. This is in a static scenario. And all this changes when sailing and the leeward stay goes slack. Compression comes from downward forces imposed by stays, halyards etc. Fore and aft and sideways support comes from angle of stays and spreaders. A mast will break as soon as sideways or fore and aft support is lost. With no spreaders the compression bends the mast and chord distance from mast base to mast head is lost so the mast bends and stays go slack and bang. I think we are agreeing but being lost in the explanations
  7. Well yes. But the 3m will offer more sideways resistance. Compression on the mast will be the same. But boats have gone wider to offer more sideways support. They have also gone to longer spreaders for the same reason... to hold the mast up and in column. What do think the loadings are on the mast step of a unstayed cat rig.
  8. Not in a masthead rig booboo. But yes in a fractional rig (as the force has gone from a more aft "pull" to a downward pull) This is where you are confused. Side stays always have an opposing stay working against them. So all forces equalise and transferred to the mast. For a masthead rig - 10 tonnes of back stay load 1 inch behind the mast is the same as 10 tonnes thirty feet back when there is a fore stay acting in a opposing force. So all forces are transferred down the mast.
  9. Correct. The lock system is best followed by 2:1. I was with WT diagram 100% until the chain plate point. Chain plate angel, spreader angle and length on serve to support the mast, pre bend the mast, fore and aft and side ways. Compression of a mast from the stays only come from the loadings we put on the stays.... until we hoist a sail and fill the sails then the forces of wind, keel, wave loadings, stiffness of sail cloth, sail shape, crew weight, rigging and running rigging strenght and stretch comes into play. Maybe mythbusters would be a good demo.
  10. Compression on a mast is in more than one sector. Below the stay/stays attachment And above the stay attachment (hounds) The angle of the stays has no bearing on compression. The tension you put on stays does. In a 2:1 main halyard its most advantage is the Mast head to hounds compression. Of course the angle of the stays matters! That is why a mast has spreaders! If your argument is true then we can all take our spreaders off have save a lot of weight! Incorrect. Compression on a mast is a downwards force not a sideways force. All the spreaders do is keep the
  11. To simplify... There is halyard compression and mast compression acting in a downward force on the mast All have 100kg of compression on the mast. (On the sheave pin/splice pin) The 2:1 has 50% less loading on the halyard than a 1:1 system.- The lock system has the least amount of halyard stretch potential and no halyard loading The 1:1 halyard has 100kg less the friction deduction of the sheave it passes Plus the 100kg of. Mast loading loading =200 kg The 2:1 has 100kg mast plus 50kg halyard The halyard lock has 100kg mast. No myth just maths and physics.
  12. Compression on a mast is in more than one sector. Below the stay/stays attachment And above the stay attachment (hounds) The angle of the stays has no bearing on compression. The tension you put on stays does. In a 2:1 main halyard its most advantage is the Mast head to hounds compression.
  13. Not quite. In a vector load diagram you have down ward forces imposed by luff and halyard that are in equilibrium ( or the sail would fall down or go up) the force imposed on the Halyard ( luff as well) is one downward force. The compression on the mast is one force from these. The bend from this compression is dependent on the mast section. But the most compression, or downward force is the effect from the main sheet ( or kicker/Vang if using to tension the leech). That is a downward and aft pull. Remember the boom is a big lever of fulcrum acting on the mast with great load.
  14. Here is a photo... http://www.flying15.org.uk/news/flying- ... in-halyard By virtue that the head board of the sail is supported by two ropes equates to a 50% reduction of load on the blue halyard down the mast. Thus - the compression on the mast between the hound and masthead (3/4 rig) is reduced. The percentage of reduction on the rope is 50% but the reduction on the mast varies from mast to mast. Having the 2:1 in the mast is a complete waste of time as the compression is still there and the headboard is only supported by one fixed point. Not 2 as in this setup attached.
  15. Grant, that's a 1:2 set up and only someone on bad bad drugs would use that.
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