Corey Lees wrote:Again thanks Arne, How does sail area forward of the mast change how the sails behave on the different points of wind. Lets pretend we have a monohull automatic correcting center of effort.

I suggest you make a 6 - 8 panel test junksail of say 0.5sqm (5sqft) and hoist it outdoors to let the wind play with it (a broom handle would be a fine mast). Then play around with sheets and parrels, and different balance, and you will learn more than by reading. Try some of the parrels on "Junk Rig for Beginners":

http://goo.gl/vzGLzi

Good luck,
Arne

I guess the term "more balanced"  is only used to describe more sail forward of the mast. This is not good or bad  -  it depends. I use quite little balance in my sails. This is partly to not distort the camber too much when the mast is on the lee side, and partly to hide the mast in the separation bubble (according to some aerodynamists) on that tack. However, if I were to make a flat sail or a split junk sail, then 30% balance sounds like a good idea. Now, Paul Thompson also uses quite some balance in his sails on La Chica, even if he has plenty of camber in the panels, and they appear to work well. Maybe my worries about distorted camber are unfounded...

Arne

PS I guess the term also can be uses on rudders  -  more balance means more rudder blade in front of the axis. A bit funny use of the word balance  - we either are in balance, or out of balance...

Corey, I know about four meanings of the word balance in relation to boats and their sailing rigs:

First, as you point out, the balance in a junk sail is given as a percentage of sail (area or batten length) forward of the mast.

Secondly, balance between sail area and keel area (Centre of effort, CE, versus Centre of Lateral Resistance, CLR). Get it right and the boat will need no, or only light tiller input to keep the course. Get it wrong and you will have to set the rudder at a considerable angle: The boat then has weather helm (wants to turn to windward) or lee helm (wants to fall off). I have described how to get this balance right here: http://goo.gl/u9LupX

Thirdly, one uses the term a balanced hull: A balanced hull is a hull that does not alter helm balance (much) as the boat heels. To achieve this, the reserve volume (i.e. above the LWL.) in the fore sections must be similar to that in the aft sections. An un-balanced hull will in most cases want to turn to the opposite direction of the side it heels to. This could add or subtract to the CE-CLR balance situation.

Finally, a rudder itself can be made with or without balance in it: A balanced rudder have some of its area in front of the turning axis, and this reduces the tiller forces. If one makes the balanced area too large, the rudder will overbalance and thus be unstable: If you let the tiller go, such a rudder will flick to one side or the other. In contrast, if the rudder is broad and unbalanced (like on an American Catboat), the tiller forces may be high even if the boat itself is fairly well balanced. The boat feels unbalanced but the cause of it is the rudder design, not the boat or rig.

Many sorts of phrases are used to express these different forms of balance  -  and yes, sometimes they can be confusing and misleading.  Being  “light on the helm” , for instance, means just that, but it tells little about the reason. The CE to CLR could be perfect. It could also be that the rudder has been made (big and) so well-balanced that it could keep an unbalanced boat on course with light forces felt on the tiller.

Note: Many of the Chinese junks (unlike most western boats) have the rudder as an important contributor to lateral resistance. The centreboards or leeboards on most junks and sampans are placed forward of the sails CE, so much of the weight falls on the rudder (they have constant weather helm). They therefore make their rudders a lot bigger than on most sailboats in the west.

Clear as mud, right?

Arne