I would print out Chuck Holst's directions. It is easier to see the details and jot down your anthropometric measurements in inches when you have a piece of paper in your hand. You might have missed the cross-sections shown in one of the illustrations (bottom). I'm working on my second GP (number 3 total)... It's not as hard as it looks.

Here's a shot of a storm paddle I made from cedar strips www.ChipSandresky.com/paddles/images/g_paddle.jpg The shape is hard to capture in a photograph.

www.ChipSandresky.com