After seeing the discussions of broken paddles, laminations, etc, I became curious about the structural considerations, specifically grain orientation and lamination orientation.

The reality is that grain orientation is key to both. Wood is strongest if it is loaded parallel to the grain. For example, the allowable working stress for dense (tight grain) select structural Doug Fir is 1500 PSI compressive if the load is parallel to the grain. Compare this to 455 PSI if the load is perpendicular to the grain. I don’t have the data for other woods but it would be similar

For wood, compressive strength is the limiting factor, not tensile strength

If the load is perpendicular to the grain, you have another problem…the grain is at an angle. As the angle increases, the load carrying capability decreases.

Here is the easy way to think of it. When you look at the paddle lying flat on the floor, you want it to look like a split log, not a shingled house.

Side note here, dry Doug Fir is about 25 percent stronger than green Doug Fir. So keep your wood dry.