In general (very general) smooth transitions do a better job of distributing loads and evening out stresses. Abrupt surface changes (scratches are a perfect example) act as stress risers. If I see a good website I'll letcha know.

> Does a greenland paddle need a "shoulder" where the
> shaft meets the blade, or not? My knowledge of engineering is just
> about zero, but it seems there would be a concentration of stress
> where the two meet. Would a shoulder help by strengthening this point,
> or would a smooth transition from the shaft to the blade do a better
> job?

> Below is a link to an article that provides a detailed drawing
> of a how a shoulder is made (see Step 4 in the diagram). An equally
> convincing article says there is no need for a shoulder. Any thoughts?
>