Finding the right size of blades needed for your boat is not always easy. Oars that are too long or too short make it difficult to control your boat in the water. So when it comes to choosing the right size, one needs to consider several factors including the size, weight and manoeuvrability of the boat. For this article we will discuss two different approaches.
Firstly we will start with a less number driven approach. To estimate the rough size of your oars, measure the widest part of the boat (beam) and then multiply the number by two. You can also use the length between the oar locks, but we will discuss that approach later on. Also consider the weight of the boat and the level of ease with which you manoeuvre it. The weight of the boat is inversely proportionate to the length of your oar, i.e. the lighter the boat, the longer the length of oars you require. Start with the rough number derived initially by doubling the length of the beam. From there on, try to make adjustments based on weight and ease of navigation. Start with an oar length longer than that derived from the magic number, and then work your way out by gradually shortening the length until you feel the size is right.
If you feel that the previous approach is not working for you, try out the one discussed by Sheward Tenney. You can determine the length between the oarlocks and use that magic number in the following equation to derive the proper length of the oar.