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PostPosted: Thu Aug 15, 2013 8:43 am 
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I've looked around here and online for examples of anti-mast rotation setups for my H18, that help prevent the mast from slogging back and forth in light air downwind runs and lumpy water. Of the two types I've read about: cleated lines and bungees, I prefer using bungees.

I've experimented with a bungee run from the rotator end out to where the front crossbar meets the hull deck, but that usually pulls the rotator down onto the boom, where the block I have attached to the end of the rotator for the outhaul gets constantly mashed against the boom.

Who here has installed anti-rotating devices, and what have you used?
Thanks!

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PostPosted: Thu Aug 15, 2013 12:05 pm 
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First off, what you're refering to is more commonly called a "positive mast rotator". It is used to hold the mast in rotation and induce extra rotation against the force of the shrouds for downwind sailing.

There are really two versions that I've seen/used on the racing scene. The first is a "boom vang". Generally one end is secured about two or three feet back on the bottom of the boom (can be tied to the boom and held in position by tieing back to one of the mainsheet bales) and the other end is tied to the dolphin striker post or tramp lacing. Vangs do a good job of holding the mast in rotation but have some drawbacks. The first is that if you forget to release them, you can break your battens or mast. This can be overcome however by using a heavy bungee cord in the system. This will make it more or less self tending. The biggest issue I had with the vang, and the reason I eventually took it off my boat, was that it really interferes with the crew working the front of the boat. My crew hated it, and so we ultimately took it off the boat.

The other option is to create a setup similar to what is used on many H17 and H20s. You create a bridle of bungee that connects to each bridle tang and reaches back to about one or two feet in front of the mast. Then you take a loop of thin line, place a pulley on the line and tie each end to the end of the mast rotation bar so that it forms a loop that passes in front of the mast. Connect the bungee cord to the pulley. The forward force of the bungee will pull the mast into rotation. This system is fully self-tending. The only issue is that the bungee wants to pull the rotator arm downward. To overcome that, I installed a small stainless fairlead onto the front of the mast, tied a thin line to one side of the rotator bar, up through the fairlead, and then back down to the other side of the bar. This keeps the bar from dropping down and dragging against the boom.

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PostPosted: Thu Aug 15, 2013 12:53 pm 
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that's exactly the kind of description I was looking for, thank you.

installing a boom vang is not an option, a vang normally is used to pull the boom down gybing downwind to maintain flatter sail shape. as bowman on both a J105 and J109 I've plenty of experience with it's use, and your comments about it getting in the way are right on target.

the description of the forward bungee system is more in line to what I'd use as a solution.
thanks again.

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PostPosted: Thu Aug 15, 2013 4:45 pm 
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Location: Chilliwack, BC
That's close to what a lot of us are doing now also....
another option:
a bungee from either where the bridle connects to the inside deck or where the forward bungee for the trapeze is tied off, back to the mast rotator, attached by a clip large enough to go over the rotator. You need, as you discovered, a line that keeps the rotator off the boom, (mine is tied to the diamond wires), and a small line that ties to either side of the rotator in front of the track as a stopper to keep the clips from jamming in by the bolt. There needs to be enough tension to ensure the mast rotates forward of the beam on the appropriate side as needed.

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PostPosted: Fri Aug 16, 2013 6:58 am 
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Interesting.....
Will this work if I am running a spin?
Likely not?

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PostPosted: Fri Aug 16, 2013 9:12 am 
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John Lunn wrote:
Interesting.....
Will this work if I am running a spin?
Likely not?


If you're running a chute, you probably don't need to worry about postitive mast rotation or over-rotating. Generally when running the spinnaker, the main is sheeted in somewhere between an upwind and a close reach setting, so you would want the mast rotation to be the same. Plus the added mainsheet tension would likely help hold the mast in rotation.

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PostPosted: Fri Aug 16, 2013 9:20 am 
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I wondered about that... thanks SRM.
Chris, how is that spin coming along?

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PostPosted: Fri Aug 16, 2013 10:17 am 
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John, slooooooowly... too slowly.

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