I have a PA sail (Pacific Action Sail) on my Hobie Revolution kayak that looks a similar setup, about $400 for the whole sail rig that can be fitted to most SI or SOT yaks.
Last Sunday it got me out of some deep water off Rockingham when I was being circled by a large Mako shark, the video from the encounter shows the sail in action. They are a very quick sail to set and stow and designed so you can still paddle while it's up. Sizes are 1, 1.5 and 2.2 square metres, I have the 1.5, they are on the net or In2kayaks. My next purchase will be a shark shield

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