Hey all,
European winter is coming, time for theory

I would like to understand the technical background of paddle blade designs. (Outrigger, SUP, Dragon boat)
Why do blades look like that?

What is the technical background or influence of

- Blade area (optimum for specific applied force?)
- Outline (Teardrop, .)
- Blade angle
- Implementations like V-Drive, .
- Other influencing factors?

I think the basics are pretty clear, but I have no idea about details.

Does anyone know a good resource like books, papers or websites?
Or even some experts around here to help out?