(I joined KF specifically to respond to this posting)
I launched you that Thursday night and watched you go downwind.
Some of your statements concern me.
You decided to self rescue when you got to the powerlines?? Before you arrived at the powerlines on your downwind run you should have been mentally prepared and well setup for a self-rescue. If you delay your preparation, you will drift past the last get-out and go to Decker Island. It's safe to say based on your experience you should have been mentally playing your self-rescue technique in your head before I launched your kite.
Going by your description of getting out of the water, the decision to self rescue was not made at the right time. You drifted into an area that is less favorable for getting out. Does that mean you started your self-rescue too far into the channel or you didn't hold your kite right; I wont speculate.
Sherman Island is at the end of it's season so you will get fewer and fewer days as time goes by.
I encourage you to check out www.bayareakiteboarding.com
. It'll give you more local support from people who better know the area (I am a member).
Sherman Island will not teach you how to kiteboard; it will teach you how to recover from getting your butt handed to you...hopefully less and less with each time out.