It what was used long before motors were invented!
http://www.livestrong.com/article/203976-how-to-select-rowboat-oars/
Step 1
Choose the type of material for your boat oars. Oar maker Shaw and Tenney recommends spruce as a light yet durable wood that works well with most boats. For heavier boats or extremely hard use, choose oars made of ash, which is heavier and more durable than spruce. Synthetic oars made of plastic, aluminum or fiberglass are also available.
Step 2
Calculate the proper length of the oars by first measuring the span of the boat from oar lock to oar lock. Divide the span measurement in half, then add 2 inches to determine the outer loom length, which is the length of the oar from the end of the grip to the fitting that holds the oar in the oar lock. Also, divide the span measurement by 7 and multiply the difference by 25 to calculate the approximate length of the oar.
Step 3
Select oars with an inner loom and length that match the measurements as closely as possible. For instance, if your row boat measures 5 feet from oar lock to oar lock, select an oar with a loom that is 2 feet 8 inches long and has a total length of approximately 9 feet 4 inches.
Step 4
Choose a grip. Most rowboat oars that are 7 1/2 feet or longer come with a tapered grip. Select a barrel grip for shorter oars. For oars longer than 10 feet, consider a double grip to accommodate two hands.
Step 5
Inspect the oar blade shape. Choose a flat blade for an all-purpose oar. For more pulling power, select a spoon blade. For larger boats or more performance, try wide spoon blade oars.
Step 6
Select an oar lock type. Traditional oar locks use a metal collar, called a button, that prevents the oar from slipping through the oar lock. A leather sleeve below the button protects the wood of the oar from wear. Plastic sleeves that attach to the oar and replace the button and leather are also available.