What size oar do I need for my dinghy?
Mark Matthews responds:
While oar length is yet another question of personal preference, there are a number of factors to consider. You can start by examining the stowage characteristics of your dinghy. There is no sense in having a set of oars that won’t fit inside the boat. Take in account other passengers, the outboard engine, if you have one, and its tanks, if there are any, as well as other gear that may end up in the way of the rower. Generally speaking, the longer the oars, the more power you’ll be able to get out of them and the less strokes per minute you’ll have to use to get where you are going. Of course longer oars can make maneuvering in close quarters somewhat trickier.
For the purpose of this brief treatment, we’ll assume your dinghy isn’t an inflatable. Rowing an inflatable is inefficiient and can be a fairly futile experience, and it's usually a sign that the outboard has gone on sabbatical. Some rowing dinghies have two sets of oarlocks, depending on whether there is one person in the boat or if crew and gear are also along for the ride. You’ll also want to have some kind of collar on the oar that prevents it from slipping through the oarlock and beyond your grasp.
Still can’t decide what size oar will be right for your dinghy? Try this formula from the good folks at barkleysoundoar.com. The example they give is better suited for a large dinghy, but you'll get the gist. Take one-half of the dinghy's beam measurement in feet (taken at the oarlocks). Multiply that figure by 25, divide the result by seven, and round the answer up to the nearest six-inch increment if the boat is over 10 feet long, or down if the boat is under 10 feet long. Let's say that your boat has a four-foot beam and it's roughly 12 feet long. Multiply two (half the measurement of the beam in feet) by 25 and you'll get 50. Now divide that by seven and you'll get 7.14 feet. Take that and round it up to seven feet, six inches and that's the length of the oars that you need. Good luck and happy rowing.