I installed a Northwater deck bag on my old Chesapeake Light Craft Tred Avon double kayak today. The bag has a folding Velcro panel that is intended to be secured over deck bungee cords or straps.  I had my wife sew straps to this panel and then I screwed buckles to the deck.  This provides an incredibly secure means of fastening the deck bag to the kayak.  Check out this short video that shows the installation...

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