I am trying to design a compression vang for a main of .66m2 or 1035 inch2, I have came up with a few ideas. The main problem is, I don’t what to cut the tack of the main away to clear the vang. Are there any ideas out there?
Depending on the class, do what they do in the 49er class. Put a pocket in the sail and have sail come down both sides of the compression strut. Some classes will hit you for 2X sail area in that zone though since it comes down both sides. Some classes wont allow it at all.
Why do you want compression, I have a couple ideas that I have seen work in other boats, but each is utalized for different reasons. Trying to get the main lower to the deck? What is you ultimate goal in the compression design?
Why not have twin struts if doubling the sail is illegal? You could then have a axel going through the mast, and anouther in a slot cut in the boom. Then the struts can be of fixed length, to adjust the amout of vang all you then need to do is move the axel back and forth in the slot using lines or even a screw type ram inside the boom itself.
Check out the Wylie designed Open 60 (fullsized) Ocean Planet. It has an unstayed mast with a compression vang. It actually has vang struts on either side of the mast so the tack remains normal.
A compression vang can also create better lower mast bend when it’s applied. It does this by pushing the mast forward and higher up than a convential vang which actually pushed the boom in to bend the mast and depower the lower draft stripe.
Download Attachment: [ Ocean Planet.jpg](http://www.rcsailing.net/forum1/data/VMG/200382915957_Ocean Planet.jpg)
heres a model with a similar setup.