Short answer: yes, but I wouldn’t treat a boat deck like a patio. Urban outdoor furniture is built for plazas, rooftops, and courtyards, so it can handle sun and rain, but a boat adds saltwater, constant vibration, wind, and tight spaces. Some pieces work well; others will fail fast.
The best candidates are powder-coated aluminum, marine-grade stainless steel, HDPE, teak or other weather-resistant woods, and UV-stable plastics. Avoid mild steel, cast iron, untreated wood, and delicate glass tops unless they are specifically marine-rated. Check hinges, screws, and feet—replace standard fixings with stainless steel where possible, and use non-slip pads or secure mounting so chairs and tables don’t slide in choppy water.
Cushions are the weak point. Regular outdoor foam can hold moisture and mildew; marine-grade quick-dry foam and solution-dyed acrylic fabric are much better. Also think about weight and size: lightweight furniture is easier to move, but it must be stable and stowed safely. Folding or stackable pieces are handy on smaller decks.
So, can urban outdoor furniture be used on a boat deck? Yes, if you choose corrosion-resistant materials, upgrade the hardware, secure everything, and accept a bit more maintenance. If the furniture is cheap, heavy, or has exposed steel, I’d choose dedicated marine furniture instead.