I built my paddle using the hollow birds mouth construction and was very pleased at the results. Having read the old posts, as I’m sure you’ve done by now, I had to try it myself. I used basswood for the shaft, 6 oz. glass (wrapped twice around the innertube), cedar, mahogany and ash for the blades.
The blades are reinforced with glass around the extreme edge, the tip and on the back of the blade 1” wide running down the center onto the shaft.
My solution to the blade-to-shaft connection was a 7 to 1 scarf joint, which was reinforced by the 1” strip of glass mentioned above.
So far the 2lb. paddle has performed very well. I’ve dropped it, banged it, stepped on it, stabbed it in clay going full speed ahead and having to pull it out as it tried to stay behind. I thought that move would break it for sure. No question in my mind about it's strength.
The paddle has slight flex on my hardest digs.
Good luck paddle building.