ARC 21 mast rotation

[Eric2101]

What is the theory and control of the Arc21 mast rotation? I am trying to understand how I can limit mast rotation in light to moserate breeze. I feel that the mast is rotating well past 90 deg and ahead of the apparaent wind.

[Tom Haberman]

Eric,

What do you mean when you say "well past 90 deg."? In referance to what?
The clew plate is the primary rotation control. The stock plate is 10.5" x 2" and has 5 holes that are .625" in diameter. The most forward hole should be a maximum of 101" from back of luff bolt rope.
The stock mast prebend is 3.25". The aluminum bottom batten must be used.
With the above parameters you should be able to limit rotation when going to windward quite easily. Typically with the mainsheet hook in the most forward hole the sail track will point at the sidestay on the leeward side of the boat.
When sailing off the wind you want more rotation and this will occur automatically as you ease the mainsheet tension.
I have nerver had a problem with over rotation on either the ARC21 or 22.
In extremely light air we sometimes jam our foot against the sail track to stabilze the mast in waves or bumpy water. This is a simple and effective method and is rarely required. Either you or your crew can accomplish this with ease because at least one of you should be forward when conditions warrant this increased rotation & stabilization.
In short over rotation has not been a problem with the ARC21 when all standard components and sails are used.
As a last resort you should be able to add one more forward hole to the standard clew plate without any problems.
Please let me know how you make out after you check the above items.

[Eric2101]

thank you Tom.

I have been using the middle hole exclusively. I will move it forward on the next trip out.