I lost my boat oar for my 8-ft long pontoon row boat and I need a new one, But I don't know what kind to get. I only lost one oar and the other one is hard plastic. I lost my oar because I let go and the oar lock snapped and took the oar with it. So is an aluminum oar good? or is hard plastic better?
Whatever you get -- aluminum, wood, plastic -- you should be using a matching pair.
Generally, aluminum and wood are both stronger than plastic, especially if you're talking at the shaft. (Sometimes you'll see aluminum shafts with plastic blades.)
If your oar lock snapped, you should be thinking of getting a stronger pair of oar locks.
Finally, consider bringing the remaining single oar and oarlock on longer trips as spares.