I sailed a Nacra 16 yesterday for the first time. I have a question about the spanner, I think it is called on the front of the mast. There are a couple of lines attached to this SS protrusion thingy attached to the mast. These lines go port and starboard through blocks to jam cleats. Apparently this is to limit mast rotation. My question is: Where are these generally set? Should the mast position be straight in heavy/moderate winds and allow to rotate more towards 90 degrees in lighter winds, or have I got it backwards?
Thanks
Nacra 16 setup
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Posted: Jun 16, 2009 - 12:19 PM
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Posted: Jun 16, 2009 - 01:24 PM
As the wind gets heavier, the mast rotation is limited to take power out of the rig. It is usually adjusted anywhere from rotating freely to pointing at the corner of the rear beam. -
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Posted: Jun 16, 2009 - 04:16 PM
The MAST ROTATION ADJUSTER has a couple uses. It can help with aerodynamic entry while going into the wind, pointing the leading edge of the mast into the wind will help with performance, the mast is actually the leading edge of the sail. While if the mast is allowed to have the flat side face into the wind while sailing upwind, it will slow you down. While sailing down wind if you can rotate the mast to 90 degrees or more, the entire flat side of the mast will act like more sail area. With a mast like mine which is just under 32 feet and approx 6 inches across it add 16 square feet. Remember less rotation will increase sail fullness and power, more rotation will flatten the sail and help depower. -
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Posted: Jun 16, 2009 - 05:19 PM
good answer HULLFLYER...
as is semi typical... the boat and its controls act differently upwind vs. downwind. -
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Posted: Jun 17, 2009 - 07:21 AM
Hey thanks for the answers guys. I think I understand. The lines were impossible to adjust while on a tack so I assume you have to set them before going out or put the boat in irons and do a quick adjustment then.
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Posted: Jun 17, 2009 - 07:58 AM
sounds to me as if they are positive mast rotation lines, that's if you mean boomless nacra 16sq when you say nacra 16
positive mast rotation is quite different to the more usual boom mounted mast rotation, so be careful to know the difference when reading about them
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Posted: Jun 17, 2009 - 08:11 AM
Yes, this boat had no boom. Just a small 2'(?) track on the sail for the mainsheet. So this is a 16sq? Do the same rules apply for adjusting the mast rotation on this boat or ? -
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Posted: Jun 17, 2009 - 09:14 AM
the same concept but instead of a rotator limitor... you have/use positive mast rotation. -
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Posted: Jun 17, 2009 - 09:28 AM
You lost this newbie with that statement. Positive mast rotation? Is there another way to say that? The lines attached to the thingy on the front of the mast limit rotation on each tack. -
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Posted: Jun 17, 2009 - 10:04 AM
you may need to work on your terms a bit (get a parts manual for your boat). If you can call the part by its name, people can understand your question and answer it better...
the concepts are the same as how rotating the mast effects the sail and power... but the way it achieves this is different (since there is different hardware)
a rotator limiter works on the aft part of the mast (facing back) and connects to a boom via a single line. this limits the mast from rotating more than desired.
Positive mast rotation forces the mast into the desired position by port and starboard control lines attached to the hardware which faces forward (since there is no boom to connect it to).
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Posted: Jun 17, 2009 - 04:34 PM
That's why I love this website. I know know one hell of a lot more about that %$#!!!!! positive rotator that catches my jib sheets all the time!
Seeing it in a new light!
Positively!
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Posted: Jun 17, 2009 - 06:43 PM
hi scudman,
afaik the nacra 16sq is only made by nacra australia so that's where you'll find the best info
http://www.nacra.com.au/one-man/nacra-16sq
it is a popular 1 design class in australia and there's a tuning guide here that mentions mast rotation settings
http://www.nacra.com.au/wp-content/uploads/2008/09/11-mf-nacra-16sq-tuning-guide.pdf
probably the best place to ask specific nacra 16sq Q is the australian forum, if you can sign up, it's never let me register
http://catsailor.net/ -
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Posted: Jun 18, 2009 - 01:22 PM
Put a piece of shock cord from the point where the bridal wires and the forestay meet back to the mast, if you have diamond wires you can tie it off there or if you have a line or wire the holds the mast rotater from going to far down you can attach it there where it connects to the mast. Make sure your jib sheets are above the shock cord.
