Originally Posted by alexzn
I don't actually know how it correlates to crud-busting.
It is one of many factors, as you suggest. Some skis have a low rise height, some have a low rise angle, some have both (like the Mojo). Stiffness definitely factors in too.
My PEs are an example of a ski with a high but slow rise in the tip. They have a medium stiffness, but are among the worst crud skis in my quiver of recent years. Here's a shot of the PE (foreground) compared to the Karma (background) with both skis aligned at their forward contact points:
In addition to having a steeper rise angle to the tip, the Karmas were a bit stiffer than the PEs. I found the Karmas to be a lot better in crud. PEs were a lot better in untracked powder though.
Now, as for the Mojo, it would fit into the picture as follows: cut off and round off the PEs about where the middle of the bullseye is. That would roughly approximate the rise of the Mojo, giving the low angle *and* low rise. Mojo has a similar flex to the PE on my scale. That combination of a low, slow rise and medium stiffness is what limits the Mojos in crud in my opinion. It's offset a bit by the width, and the fact that I can ski them in a 187cm to get the tips further out in front (PE was limited to 179cm).
Here's one more picture, showing the Mojos in ski-closet storage next to my Watea 94s (both skis are standing vertically against the wall, but I rotated the picture sideways):
The forward contact points are not lined up here, but you get an idea how shallow the Mojo's tips are in comparison to the Wateas (which have an almost toboggan-like curl to them). The Watea tips are roughly twice as high, maybe a bit more.
In an absolute sense, I think the rise angle correlates to crud-busting as follows: low angles want to ride over the crud, while steep angles want to plow/poke through the crud. That angle, when combined with the rise height and stiffness, determines the ultimate behavior. The combination designed into the Watea's tips (steep angle, high-rise, medium stiffness) really works well in crud for me. The skis ride over small stuff, and bust/plow the rest.