Laser 161752 Tynemouth |
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Laser 28 - Excellent example of this great design Hamble le rice |
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Laser 140101 Tynemouth |
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List classes of boat for sale |
Rig Tension |
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about a boat ![]() Groupie ![]() Joined: 25 Oct 06 Online Status: Offline Posts: 60 |
![]() ![]() ![]() ![]() Posted: 09 Feb 15 at 2:25pm |
SO looking at the tuning guides for the Mirror. Using the P&B guide for the Bermudan mast it says use 160lbs of rig tension. I pulled on around 140lbs and did not want to go any further. As it was the shrouds would give off a high pitched ping when plucked and I had the mast rake correct. Given the boat is a 1986 Bell built boat I did not want to over do it on the fittings. So is 160lbs really what would be required?
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JimC ![]() Really should get out more ![]() ![]() Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6662 |
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If it makes you feel better that's really not a very big load compared to some boats. I used to use 600lbs down the shrouds on my Cherub, and much the same down the checkstays which terminated at the same point, but the boat was built and engineered to take those sorts of loads, and in any case they wouldn't be necessary on a Mirror. Trapeze boats need far greater tension.
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Rupert ![]() Really should get out more ![]() Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956 |
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On an old Mirror, the most likely thing to break with too much rig tension is the shroud plate, which are often screwed into wood which is slowly rotting, and certainly wet. Once you have checked these are OK, 160lbs should be OK. Worth checking the sheerline isn't distorting.
Have to say, though, that I doubt it will make a huge amount of difference to the speed, putting the extra tension on. Mast rake much more important. |
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Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
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Time Lord ![]() Far too distracted from work ![]() Joined: 03 Dec 13 Location: Warwickshire Online Status: Offline Posts: 301 |
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Once saw an old GP14 being brought up the slipway as it was taking on water. As it went onto the trolley, you could see the foot of the mast sticking 2-3 inches out of the bottom of the boat.
The owner had been told that he needed to put on more shroud tension so that he would go faster! Had the opposite effect!! |
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Merlin Rocket 3609
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zippyRN ![]() Far too distracted from work ![]() Joined: 14 Sep 06 Online Status: Offline Posts: 437 |
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indeed so , i also wonder whatthe rated working load of the old style cast eyes is ... in gunter rig days mirrors ran minimal rig tension
160 lbs is small potatoes in rig tension terms but if the boat structure or the fittings aren't sound .. |
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NHRC ![]() Posting king ![]() Joined: 13 Dec 13 Location: Lymington Online Status: Offline Posts: 102 |
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Safe working load on 3mm wire rigging is about 126kg which is 270lbs that is with a 4:1 factor from the average breakload.
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Daniel Holman ![]() Really should get out more ![]() Joined: 17 Nov 08 Online Status: Offline Posts: 997 |
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I thought 3mm wire broke at a tonne?!Or is dyform different?
Never ceases to amaze me how much load can be taken by light structure as long as the structural arrangement is adequate and the reinforcement is applied correctly |
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NHRC ![]() Posting king ![]() Joined: 13 Dec 13 Location: Lymington Online Status: Offline Posts: 102 |
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Non Dyform breaks at about 720 kg as an average break test. To be safe i would say to you that Dyform is in the 850 kg mark, can go at over 1100kg but averages about 850-900kg from testing.
Edited by NHRC - 09 Feb 15 at 11:59pm |
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NHRC ![]() Posting king ![]() Joined: 13 Dec 13 Location: Lymington Online Status: Offline Posts: 102 |
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The 3.5 mm Dyneema SK99 we have been tested averages at just under 1700kgs.
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Daniel Holman ![]() Really should get out more ![]() Joined: 17 Nov 08 Online Status: Offline Posts: 997 |
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How is that different from SK78 or 90 then?
Playing creep off against modulus.. |
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