Surfing backside on the finless has been problematic for many people including me. I constantley revert back to finned surfboard thinking and stomp on the back corner in hopes that it will help the edge dig in to the face. With a thin alaia this works a little but with the Seaglass Tuna and Albacore it has little success. I have been studying two great surfers, Jacob Pedrana and Ryan Heywood (the photographer) going backside and I realized that they are further up the board and actually putting more weight on their front foot. They let the curves of the tail do their thing and suck into the face of the wave on their own - which is what they are designed to do. Please check out this video of Jacob and friends at Tea Tree, Noosa Heads
I have two tips to help anyone sliding sideways on their backside. First, try dragging your hand in the wave like you are lying back - that is the hand towards the tail of the board. This stance seems to put more weight on your front foot's heal. Another tip is from Ryan. He found that surfing parallel stance facing forward helped him. I think this stance, again, lets the tail do its thing and grab into the wave giving you control in trim and not sliding sideways. The board Ryan is riding is the first blue and white Albacore prototype. The blue peeled off and it is now white. This is the same board from the Noosa Festival last year where the blue was peeling off. This shows that the board can withstand a full year of daily surfing! The blue peeling off is no longer a problem.
Also, I am always looking for new names for finless moves. I will now call the big forhand turn when going backside the "Cutback Supreme". Jacob does severa beautiful Cutback Supremes in this video. Please let me know if you think of a better name or any name at all for a move.