I would recommend just plain old macon blade oars (the traditional shape) as being the easiest and most forgiving, followed by spoons (sleightly better performance, but harder to use). Hatchets, big blades, and the other more exotic shapes are good for specific applications, such as racing on flat water, but I doubt you would notice much difference unless you are a fairly skilled rower. I think the most important factors are the weight and balance of the oar, and the size of the grip. All the energy you have to put into holding on to the oar and recovering for the next stroke is wasted effort. Minimizing wasted energy is crucial, especially over long distances.

The limiting factor on speed is the length of the boat, so even if you are in fantastic shape and have top-of-the-line oars, you won't see a huge change in performance--All of the super fancy sweeps are aimed a racing crews who are trying to shave off a few tenths of a second (not something most of us have to worry about).

Poke around on youtube and you can find any number of videos on proper sculling form. If you're rowing tandem, coordination and timing have a much greater impact on performance than the type of equipment you use (one of the reasons rowing crews carry a coxswain). The Concept2 website is a decent place to start your research--they have some videos on technique and training, as well as descriptions of the different types of oars available.

correction--macon and spoon oars are the same thing. I meant to say straight blade is the easiest, followed by macon/spoon.

Hey psimian...

I built the tandem wherry last winter having never sculled before in my life. You can check out my photoblog of the build

https://plus.google.com/photos/101115369023224475103/albums/5950391411489479089?banner=pwa

I outfitted it with a pair of Piantedosi row-wings and concept 2 oars with hatchet blades. I didn't find the hatchet blades difficult to use at all. I catch the occasional "crab" now and then, but for the most part, I think they're great. 

I learned my technique by watching YouTube videos (tons of em out there from lots of different groups) and then taking my video skills out onto my local lake. 

Sometimes I row solo from the center position, but early last rowing season, a friend wanted to try it out with me, and we discovered we were compatible rowing partners (similar size, weight, strength, and budding passion for the sport) and we rowed 3-4 times per week April through November, when the lake finally froze over. As we developed in skill and strength, we culminated our rowing season with a several hour row down the Milwaukee river into the inner and outer harbors of Milwaukee. Got lots of appreciative comments from other boaters and people watching us from the shore! Tons of fun. 

This winter, as I'm building my Welsford Navigator, I've taken my rowing indoors. My local gym has some concept 2 indoor rowers, which while not the same as being on the water, are keeping me pulling my own weight. 

Good luck on your build, and have fun sculling!

Good point John, I was thinking about my own build and completely forgot that the wherry uses sliding seats. That makes quite a big difference, and tips the balance in favor of one of the curved blade designs.

If you're rowing from a fixed seat you have a high tempo (roughly 30 strokes per minute) and a short stroke. Flat blades make sense in this case because they are easier to get in and out of the water quickly and smoothly, and the stroke arc is too short to see much benefit from a curved blade anyway.

From a sliding seat, your tempo will be significantly slower (roughly 20 strokes per minute), and you want to maximize the power of the oars over the entire (much longer) stroke. This is where the curved blade comes in--it makes the oar more efficient, particularly in the first part of the stroke just after the "catch." Since each stroke is longer, you have more time to get set up properly for the next stroke.

There's a thread on the hatchet vs. macon debate here.

You'll adapt to whatever style you choose. The most important thing in either case is to get oars that are as light as possible so you don't waste energy.