Just reporting back on the earlier device. I gave the dual bungee and rubber yoke Ama attachment (second one in the video) a pretty good workout yesterday in very choppy waters. These condistions formally sent my boat's Amas bouncing and dropping off the Aka by a couple inches. With the new bungee and yoke, the Amas never bounced nor dropped a single time. In fact I never detected any movement whatsoever. So for anyone that doesn't want to go to the trouble of making a hard, positive retention device, this is probably all anyone would ever need and it's not very hard to make.
I'll repost the link to save interested parties from having to a search of the earlier thread. The one I used yesterday is the second one in the video, that uses two separate bungees, one on each side of the rubber yoke.http://www.youtube.com/watch?v=f_vzcxaP66w