I've twice had the misfortune
to have to row a 4m rescue rib fitted with oarlocks, both times in a river with 3 knot current. I'd normally expect to row a 4m boat easily, but rowing this thing is just horrible. There was no way I could even maintain my position, just guide my progress (?) as Des says.
The tubes are not stiff enough to support the oar properly, even with the rowlock mounted on a 8" long piece of stiff plastic bonded to the tube, with even moderate force the rowlock twists forward and the oar tries to jump out the top. Better than nothing in a small boat where a standby engine is not possible especially if you're on your own, I'm afraid that you'll have limited success on a larger boat. If you do go ahead, try to fit a fully enclosed ring of some kind that the oat cannot jump out of.
If you want a pic of the arrangement on this boat let me know and i'll post it after Hurrican Ivan has passed through, if we still have the boat!