probably Gile[s] is setting EntityFX to 1 by default, I guess you can change that. A good object for caustics studies are wales etc.. There may be some movies somewhere in the web.
The caustic effect is only visible on top of them. Not sure how far you want to go, but a proper solution would be an additional low poly hull that is using vertexAlpha to become more and more transparent on the sides and finally the bottom. you will then have to UVmap it in plane mode, using the X/Z plane only.
That said, you may have to fight Z-sorting troubles when using multiple Alpha objects (and I guess you will, with or without such a hull).
I think you can use an animated texture parallely to Positiontexture. So the animation will "wobble" and PositionTexture will show the motion of the sub.
Additionally you may try to use ScaleTexture depending on the (underwater) depth of the sub (the deeper, the bigger the caustics), not sure of that.
The caustic effect is only visible on top of them. Not sure how far you want to go, but a proper solution would be an additional low poly hull that is using vertexAlpha to become more and more transparent on the sides and finally the bottom. you will then have to UVmap it in plane mode, using the X/Z plane only.
That said, you may have to fight Z-sorting troubles when using multiple Alpha objects (and I guess you will, with or without such a hull).
I think you can use an animated texture parallely to Positiontexture. So the animation will "wobble" and PositionTexture will show the motion of the sub.
Additionally you may try to use ScaleTexture depending on the (underwater) depth of the sub (the deeper, the bigger the caustics), not sure of that.