Engineering and theory are fine and dandy but they also state that a bumble bee can't fly. Boat building is an art.
I always wondered how sculling works. I still don't understand it quite just yet from the explanations in the previous posts which bring me back to my physics classes in college...

all we're miissing is the use of calculus to figure out the area of the water under the curve of the oar

I figured I'd one day meet someone with a sculling boat and ask for a demonstration.
I wholeheartedly agree with the comment about engineering theory and the evolution of things - whether we're talking about boat building by people who didn't know any engineering principles (only what worked through trial and error) or the bumblebee. I hate to hijack the thread, but this is what I have pinned to my corkboard here at work, so that I can read it when I feel nothing is going my way (I titled it "Remember the Bumblebee!"). I think it just goes to show that sometimes there doesn't always need to be an explanation for why something works

here it is:
A few years ago, as the story goes, scientists at NASA developed an interest in bumblebees. The lab folks reckoned that the littleinsect held some secrets of flight that may provide answers to questions about operating in space. After all, they asked, how could such small wings produce efficient lift for a relatively large and hairy torso? And how could a round body and flight position that violated mahy principles of aerodynamics move so efficiently through the air? Indeed, there was much to learn from the little hummer.
So the scientists set about sudying the bumblebee to discover its flying secrets. As scientists always do, they hypothesized about, scrutinized, examined, dissected, measured, timed, filmed, observed, compared, quantified, thought about and debated the bumblebee. After weeks of study they came to one conclusion: Bumblebees are not capable of flight.
Furtunately, no one told the bumblebee. The silly insects go right on believeing that flight is normal for them, despite what the best scientific minds in the world know as fact.
We can learn a lot from the bumblebee. The single most critical piece of the puzzle of life is believing in yourself and your capacity to succeed. "If you think you can or think you can't, you'r probably right" (Henry Ford). The bumblee thinks it can fly. Actually, the thought of anything else never even crosses its tiny mind. It just keeps on flying. Remember the Bumblebee!
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Since writing this, I did a google search on the subject, and it seems that more people have looked into this over the years, and they still can't quite figure it out, although they are certain there is an answer somewhere

you gotta love the scientific method! (coming from a microbiologist)