Well in theory, you can run "nice URI bulbs" with one. If you mean the URI VHO lamps, they will light up, but since it's a 110 watt bulb in a 34 watt fixture, only at a fraction of their rated output, so it's kind of a waste of money.
There is another reason why those fixtures are not the best idea... that's that they are made of steel which is not treated to handle the corrosive saltwater environment. Consequently, rust forms and metal leeches into the water as it drips off the fixture, causing you to have a bad day.
But they DO have ballasts.