The problem with using a single bladed blade shape for a double-bladed paddle is that the single bladed paddle is designed to be used more or less vertically so that the full blade is immersed in the water at then end of the stroke. The blade on the double bladed Aleut paddle is widest near the tip so you can get more blade in the water at the beginning of the stroke at a lower blade angle.
|Click on the photo for a better view. Note the single bladed paddle tucked under the improvised double bladed paddle.|
|The double cut in half on a bandsaw. The half on the right already has its extension glued to it.|
|And here, a close-up of the sliced portion of the paddle.|