We were looking at the Down Under Pot at a local garden center a couple years ago (any association to Aussie weed is unintentional), for planting use in our screened porch. I liked the glazed terra-cotta pots but couldn't warm up to upside down plants - ended up with a few of those iron cage, hanging baskets with coco-mat liners instead. The concept though has been proven to work and was used for a long time - probably the inspiration for the "Topsy Turvy".
I checked out the website anyway LINK
, but was totally turned off by the marketing style (reminiscent of tacky infomercials) and the cheesy plastic film containers. I suppose the idea is good for people with very tight yards, decks or urban balconies.
But, I imagine this would make a real mess if used above deck on a boat. Since the planter bottom requires a hole larger than the diameter of the plant stalk - to allow for growth, whenever the plant is watered, soil will drain over the plant - making muddy puddles and streaks all over the deck and/or cockpit.