If the breeze picks up, you could worry about it blowing off. Or, if only one end got loose, the wind
could swing it around twist the plastic into something Dunkin Donuts might be jealous of. Even without getting loose, the banging might get unnerving in a chop. A wave coming on deck
could also catch it, wrench it from its lashings, and make it torque one of your stanchions off. It's essentially a 12' lever arm waiting to do some work on something. It will impact moving around on deck, too. From the photo
it is hard to tell if it's a sit-in or sit-on. If the former, it could fill with water
and slide around on deck for a while- perhaps doing a number on itself, and the shrouds and ports
, besides. Unless it's pretty calm, like in your photos, you might want to see if it will fit below somehow. We're thinking an inflatable kayak
might be an option for us.