Last week I done back to back sail test in light winds ,I really can't decide which has the better power

a 2 cam sail or a 4 cam sail .

for sure the 4 cam is has better top end but down low was similar .or am I imagining it .?

Many years ago I was doing a similar test but with cams v non cam.

found it really came down to which sail could be rigged with tightest leach which in most cases was the no cam version. Plus the weight savings in the larger sized no cam and softer shape meant earlier planing and easier pumping onto the plane

however,

as soon as you plane into a lull the cam sail leaves the no cam for dead because it maintains shape.

Define power.

there's a lot to consider. Does it mean the ability to get going? Does it mean the ability to keep going through a lull? Does it mean max speed on a deep angle? etc

each one will have a different winner.

Let the Lion roar ! Theyre such an easy sail to rig n use.

Kit3kat said..
theoretically more cams mean a more forced aerofoil shape/wingshape which resists backwinding and allows to sheet in tighter and forces the sail even more to become wing-like and generate power via lift as opposed to drag. This is obviously very desireable when you boost the lift further with apparent wind by going fast.

At slow speeds, especially reaching downwind you operate the sail more in drag mode so less cams will be better. In fact going on a dead run downwind course where the sail is in 100% drag mode doesn't even work on cammed sails as they often wanna rotate out of that position whereas vintage sails are so drag-friendly they really like going on slow reaches downwind and actually feel good to use.

Ummmm...a shape can't really force a sail to "become more wing like", and there's no such thing as generating power via lift as opposed to drag.

Even if we assume that a "wing like" sail is one with a double surface then the presence of cambers has nothing really to do with it. Resisting backwinding by forcing a sail into a certain camber isn't really a thing in light winds, and if the angle of attack is wrong then having a "force' shape will do nothing. Either you will be under-trimmed or over-trimmed and stalling, and having a rigid shape won't effectively change the way the wind flows over the sail.

Generating "power via lift as opposed to drag" isn't really a thing in aerodynamics, unless you are talking different angles of attack in which cambers aren't really relevant. There can be high lift sails and high drag sails, but any sail that works must be creating lift (as some aerodynamicists use the term) and all sails must create drag unless going almost straight downwind. The aerodynamicists use the term "lift due to drag" because you can't really get one without the other.

Chris 249 said..

Kit3kat said..
theoretically more cams mean a more forced aerofoil shape/wingshape which resists backwinding and allows to sheet in tighter and forces the sail even more to become wing-like and generate power via lift as opposed to drag. This is obviously very desireable when you boost the lift further with apparent wind by going fast.

At slow speeds, especially reaching downwind you operate the sail more in drag mode so less cams will be better. In fact going on a dead run downwind course where the sail is in 100% drag mode doesn't even work on cammed sails as they often wanna rotate out of that position whereas vintage sails are so drag-friendly they really like going on slow reaches downwind and actually feel good to use.

Ummmm...a shape can't really force a sail to "become more wing like", and there's no such thing as generating power via lift as opposed to drag.

Even if we assume that a "wing like" sail is one with a double surface then the presence of cambers has nothing really to do with it. Resisting backwinding by forcing a sail into a certain camber isn't really a thing in light winds, and if the angle of attack is wrong then having a "force' shape will do nothing. Either you will be under-trimmed or over-trimmed and stalling, and having a rigid shape won't effectively change the way the wind flows over the sail.

Generating "power via lift as opposed to drag" isn't really a thing in aerodynamics, unless you are talking different angles of attack in which cambers aren't really relevant. There can be high lift sails and high drag sails, but any sail that works must be creating lift (as some aerodynamicists use the term) and all sails must create drag unless going almost straight downwind. The aerodynamicists use the term "lift due to drag" because you can't really get one without the other.

Not that I agree with the entire statement but I believe he intends to say that the cambers hold the shape of a sail so that it provides a more constant shape especially its draft (both depth and location). This is why foils, which are much more sensitive to changes in draft, tend to favor cambers and you see things like a 5 batten sail with 3 cambers (eg FoilGlide).
To the main point is that the answer isn't simple because 2 and 4 cam sails tend to built for different audiences and use cases. Two cams tend to be more oriented for those wanting easy planing, less tension in the sail, etc and aren't interested or lack to desire or skill to hold down a lot of area in a bunch of wind. You can make a very powerful 4 cam sail - we call these longboard sails

I have both , and I think size for size , a 2 cam has more early planing grunt because it has a slightly tighter leech. Combine that with a slight less weight and the fact the power doesn't push down on the board as hard. I think typically a 2 cam sail is the best for early planing.