JC Strap+ Inhaul pics are up!

Discussion in 'Laser Talk' started by Ross B, Apr 12, 2007.

  1. Ross B

    Ross B Guest

    go check out blog, and tell me what you think!

    i wanna hear it!
     
  2. shutterman0991

    shutterman0991 New Member

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    I think it's a pretty good idea. It would really be useful in Lake Sailing, but not for anyone in my area.


    I definitely want to see the finished product though.
     
  3. Ross B

    Ross B Guest

    right on

    dont worry, you will
     
  4. rock steady

    rock steady New Member

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    Good on you for trying something different, but... it looks a little over complicated for what would be very little gain. Perhaps post some pics of it working on your boat?
     
  5. Ross B

    Ross B Guest

    those are up next, ill get there, its a process

    im going to try and do it on an upcoming weekend, and hopefully when my wrist isent killing me, and my doc says its ok, ill be able to sail and ill try it

    dont be afraid to go out there and try your own, or make mock ups of your own, or propose different designs

    how would you do a JC Strap, or JC Strap + Inhaul?
     
  6. Ross B

    Ross B Guest

    could you explain to me how you think its over complicated, and how it could be simplified?
     
  7. Chainsaw

    Chainsaw Brmmm Brmmm

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    You can simplify a couple of things, also making it cheaper:

    No bow block. Tie one end of the bungee to the bow eye. Use a single length of bungee that runs full circuit through the sail clew eye, then hooks back on the bow eye.

    Replace the carbo's with a piece of 3mm spectra with two loops tied in it for guides either side of the boom. The spectra can be either taped or run through a saddle rivetted to the boom to stop it sliding while under load.

    Saw my wallet flash before my eyes with all those carbo blocks...:eek:
     
  8. stick

    stick Member

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    i'm still trying to understand the optimum conditions that this j-c strap is intended? this would be only useful during downwind legs in wind conditions of 0 to 5 mph? and it's just to assist in keeping the boom out at 90 degrees as your heeling and working the boat downwind. any other conditions (winds over 5-7mph), it would be rendered useless because the bungee would not overcome the pressure. No upwind, no reaching. am i missing anything else?
     
  9. fat-n-old

    fat-n-old Member

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    I am still unconvinced. The only occasions where I have seen this kind of strap used (solos) It was useful to keep the boom right against the shroud on light downwind legs. This allows the helm to change direction and heal without worrying about the sail coming over.

    We have an unstayed rig (no shrouds) and can let (or push) the boom out to ninety degrees or more, allowing us to balance with windward heal if we wish. I am no expert sailer but I can still manage this with ease. I can see that it would be far harder to achieve this light air balance if the boom was restricted by a shroud.

    Also on an unstayed rig the length of the bungee would have to be carefully adjusted not to pull the boom too far forward of the mast or do we counter this with mainsheet tension?

    Perhaps there is a reason why this kind of strap is only seen on stayed, single sail rigs. Finn, Europe, Solo.....

    Or have I missed the point (again)
     
  10. Ross B

    Ross B Guest

    "Also on an unstayed rig the length of the bungee would have to be carefully adjusted not to pull the boom too far forward of the mast or do we counter this with mainsheet tension?

    Perhaps there is a reason why this kind of strap is only seen on stayed, single sail rigs. Finn, Europe, Solo....."


    you can set the tension you like on land, but you would counter it with the mainsheet, the sail would always be out, its like sailing in 20, but in 10 and less, and this is exactly why its usually only seen on una rigs, no shrouds to deal with


    "Saw my wallet flash before my eyes with all those carbo blocks..."


    your wallet shouldent be hurting too much, the Harken 29mm Carbo Tri-Lite's are only $14.45 through APS, compared to $19.84 for the rear boom block, and $18 for the forward, and I used a Ronstan 20mm Single, that runs for $8.40. THe Carbo blocks are cheaper compared to the laser boom blocks, and in fact I would be all for replaces the Laser blocks with the Harken 29mm Carbo Tri-lits, but thats another thread for another time....

    "You can simplify a couple of things, also making it cheaper:

    No bow block. Tie one end of the bungee to the bow eye. Use a single length of bungee that runs full circuit through the sail clew eye, then hooks back on the bow eye.

    Replace the carbo's with a piece of 3mm spectra with two loops tied in it for guides either side of the boom. The spectra can be either taped or run through a saddle rivetted to the boom to stop it sliding while under load."


    The bow block is there for a purpose, for the bungee to turn, if you tied on end to the bow, and ran it throug the carbos, and throud the clew and back, it would just be turning through the clew, and i would not want all that friction back there, and it would just be messing with it, much easier to do it on the bow, plus there is the saftey issue, it much easier to unhook it from the sail, and quicker, then having to go forward at the bow.

    And I use the carbos instead of spectra because of less friction, i had thought of spectra, its a bit cheaper, and it could certinly be done that way and probably work, but its not how i would do it.

    I'm basically taken a proven system from other boats, and applying it here, its works on Finns and Europes, and I believe it will here too, no need to change an allready proven system( the wheel works, so lets not move to triangles) and it is relatively cheap, just have faith guys


    "i'm still trying to understand the optimum conditions that this j-c strap is intended? this would be only useful during downwind legs in wind conditions of 0 to 5 mph? and it's just to assist in keeping the boom out at 90 degrees as your heeling and working the boat downwind. any other conditions (winds over 5-7mph), it would be rendered useless because the bungee would not overcome the pressure. No upwind, no reaching. am i missing anything else?"


    I'm think 0-12 knots, and it would only be useful downwind of course, to help keep the boom out, slow down gybes a bit depending on how strong your bungee is

    just have faith guys
     
  11. GeoffS

    GeoffS Member

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    Last time I checked, the Finn (where the JC strap originated) and Europe didn't have stays... :)
     
  12. Deimos

    Deimos Member

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    The more I see about the JC Strap, the less convinced I am about it.
    However, from the picture it looks like the shock cord is running from the aft end of the boom to the bow. Thus the shock cord would be lower then the boom which would make life interesting when tacking or gybing. The pictures of the other class using then showed the shock cord attached around the same point on the boom as the kicker - keeping the shock cords largely out the the crew's way. Unsure what would happen if the dagger board was raised a bit - need to see it on a boat first.

    However, I think it would help a lot (as those using it will still be prating around trying to rig their boats as I cross the start line).

    Ian
     
  13. Ross B

    Ross B Guest

    tacking should be fine, it first comes to the boom at the first mainsheet blocks and goes through the carbos crosses under the boom and hooks on to the clew of the sail and acts as a inhaul, so the inhaul is the same as it usually is, just longer: it goes from the clew of the sail to the front of the boom blocks

    if you wanted to just do a JC Strap, you would just stop it at the boom block
     
  14. Chainsaw

    Chainsaw Brmmm Brmmm

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    I'm not going to go into great detail here because I can see you want this JC strap, so you should probably just get out and do it and not worry about opinion.

    Cost wise, in NZ, your design would be between $140 - $170 (with two clew hooks)

    This could be reduced to $11 by redesigning it so it isn't an inhaul.

    I do not support an 'advance' that dumbs down the fleet. Roll gybing and gybing at speed are worthy techniques to be learned. You don't need a JC strap for that. It's silly enough we a vang so pwerful that it has surpassed the intelligence of the guy pulling on it.

    You shouldn't have any problem with the wind holding out your boom in over 5 kns.
     
  15. Ross B

    Ross B Guest

    the hell do you get 140-170?

    2 carbo blocks: 14.45 X 2 = 28.90
    3 pack of small SS hooks at home depot: 3.00
    Ronstan 20mm Single: 8.40
    Estimated length of 20 feet of 3/16 bungee at 0.79 a foot= 15.80
    some small ass piece of line to tie ronstan block to bow: call it 2.00

    grand total: 58.10

    or 79.4948 NZD


    how the hell did you get 140-170!!!!!???????:eek: :eek: :confused:

    things can be cheaper, this is just an estimate of what i did, instead od using the carbo block, you can do loops with line, or use Ronstan 20's, if things go right with the rules, it would be up to you
     
  16. Chainsaw

    Chainsaw Brmmm Brmmm

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    My quote used all 29mm carbo blocks and harken clew hooks.

    Lets try again as per your above recipe:

    2 carbo blocks: $36 x 2 = $72

    3 x S hooks: Harken brand @ $23 each = $69

    or

    3 x No brand, but marine grade (“home depot” type stores here often have low grade s/s items that spot) @ $3.50 each = $7.00

    Only need two hooks really, and I’m not going to argue over $3.50, though an official standardised Harken kit would cost much more as we see.

    Ronstan 20mm single: RF20101 (ball bearing) $20.75 or RF575 (1” single) $10.15

    20 feet of 3/16” bungee: 6.67m metres @ $2.40/m = $16.00

    We use metric here so our bungee is .25mm thicker than 3/16” at 5mm diameter. 20 feet works out at 6.67m so I’ve calculated than exactly for comparative purposes even though some stores will not sell part of a metre.

    Small piece of line for tying on blocks / eyestrap and rivets to stop blocks sliding: $4.00

    Totals:

    $109.15 No brand hooks, RF575
    $119.75 No Brand hooks, RF20101
    $171.15 Harken hooks, R575
    $182.50 Harken hooks, RF20101

    Like I said, exchange rates have nothing to do with values. This is the price if you went to the store today and got them in NZ.
     
  17. Ross B

    Ross B Guest

    well dandy for you, sounds a smidge expensive in NZL compared to the US!:D

    but I guess its all relative, im assuming a sail is a bright penny more than ours?

    but you dont have to do it my way, you could tie it off to the clew: no need for hooks!

    could do spectra loops instead of Carbos: no need for carbos!

    it could be made as cheap or as expensive as you want, this is just how ive done it, and how i think it should work

    lets see how you guys would do it! lets see some pics, some diagrams, some pics of it rigged! i know im not the only tinker-er out there! lets see/hear it!
     
  18. Ross B

    Ross B Guest

  19. Georg W.F.

    Georg W.F. Member

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    You don't need the two boom blocks. Make it simple!

    If this works, it will give you an advantage. Do we want a boat that is easy to be sailed, or do we want a boat that is challenging and creates better sailors, who manage to keep the boom out without a bungee, even in really light air?
    G
     
  20. shutterman0991

    shutterman0991 New Member

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    quick question...with this, going head to wind and luffing will be a problem now won't it
     

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