In my head, the wenchyness has a lot to do with exposed shoulders and cleavage--if you go for a slightly more covered up look that might help. After all, a true sky pirate doesn't want skin exposed to an opponent. :)

When I went to a pirate event earlier this year, that's exactly what I did -- I borrowed my husband's old pirate shirt (it had shrunk and no longer fit him) and wore it with a waist cincher, a long skirt, and a tricorn hat with goggles on it.

At the Ren Fest, I went a slightly different route and wore a high-necked Victorian blouse with a waistcoat and pocket watch, along with the same skirt and tricorn hat.

My answer?
An elegant gentleman's coat over the corset/shirt. I also agree with the above comments regarding use of a shirt under the corset.

I find that even the "wenchiest" outfit can be shifted into the direction you're desiring by simply adding more layers.

And a hat. A really bit one!

http://pics.livejournal.com/mantisred/pic/00017zer/
This is one of the ways I've done it, meet Omen Thistle, my pirate, no not steampunk. It's hard to see but those are pirate breaches. When I wear the long skirts I tuck or clip them up high in front, with breaches, I'm planing on getting some bloomers, to do the same with.

You can see the sinus migraine in this pic, and I'll admit I airbrushed the dark circles out, that go with it.

I am working on an airship pirate costume as well, and instead of skirtness I am going with silk pantaloon[they're kind of like bellydancer pants!] type pants with corset and vest type things. Perhaps something like that where you could tuck the skirt up into the pants in places to show them off could give you a skirted look without being too wenchy...

I agree with the general formula of more exposed cleavage & shoulder = more wench-looking.

Depending on the weather you'll be experiencing, maybe a very full-skirted frock coat, made out of leather-looking fabric ("butter suede" is a cloth that feels similar to suede and comes in all colors) and trimmed with lots of straps and brass buckles and buttons. If you want your corset to show, make the front of the coat cutaway in the front, so it closes with long straps going across the middle five inches or so of your chest. If the weather will be hot, perhaps a similar coat, but sleeveless. I'd wear a white longsleeve pirate shirt under it all, regardless of the coat's sleeves or lack thereof.

If the coat's skirt is full enough and long enough (nearly to the knee, maybe), you could have slits going from hem to waist at the sides and back so it flares out when you spin and move around. You could put brown harem pants under it all and have much of the look of a long skirt, without the restricted mobility. Or, of course, you could put a long skirt under it if that's what you want.

At Tall Ships this year in Tacoma, where I wasn't doing Steampunk, but still pirates, two of us wore very nice frock coats over the rest of our clothing. Since I was there all 5 days, sometimes it was leggings or breeches with skirts kilted up in varying lengths and layers with a corset and nice shirts. JoAnne as Gentleman Jack had an even fancier coat worn with a nice waistcoat (vest) falls of lace at the neck and wrists and leggings with her boots.

Definitely women and pirates, but very much a contrast to the wenches. :)

What you need to do is get yourself a good pirate coat like this one: http://www.pendragoncostumes.com/Merchant2/graphics/frames/pirate_frame.gif
Because they're usually a man's costume, they don't evoke feelings of "wench". They also cover you up, helping avoid the "exposed body = wench" formula.
For a long skirt, I'd suggest hitching it up in front and wearing bloomers or britches underneath.
I also like the idea of a very victorian high-collared, ruffled blouse. With a corset or waistcoat it would still work well, but I think it would also look good without either. Especially having the collar and ruffles peek out from under the heavy coat would lend an air of sophisticated femininity to your look.
Finally, high button-up boots or shoes with button-up spats are a must, as is a large hat. I suggest wearing your hair in an updo for more of a sophisticated pirate look; having your hair down is a) impractical for battle and b) a more sexy, wenchy look of the type you are trying to avoid. Just look at all those pirate wench halloween costumes- the majority of pirate wenches have their hair down.

Ah- here's an example of a lovely pirate in a high-collared shirt and waistcoat: http://www.longislandcostume.com/images/07/capt-blye-pirate-wench.jpg
See how much less "wenchy" that looks? Although I'd have worn boots with that and put my hair up.

Corset, yes, but I think trousers and BOOTS would make it easier than a skirt.
To avoid the wench look, use an open coat. The 18th century frock coat in my icon looks period on a man, but the moment my sister put it on, with that kind of stuff under it, it suddenly looked all pirate, and the captainy sort, not the wenchy sort.
While not steampunk, Liv Tyler in this image might help too.
A pistol belt will help, but might be tricky to wear without interfering with the coat, unless perhaps you can arrange a Han Solo style holster? (Or Lara Croft holsters, for that matter :-)

I recommend a large, intimidating blunderbuss, steamed up of course.

The look you're trying to achieve should be relatively simple (there is no reason why a woman should feel obligated to be a "wench" when there are perfectly respectable occupations open to her). The important thing to remember is that pirates generally attempted to mimic the clothing of the upper classes, as a way to show off their wealth (being a pirate was as often as not simply a means of obtaining money; more sentimental or ideological interpretations have been retroactively added to this sort of venture capitalism by the modern public).

Now, it is somewhat difficult to approach this problem simply because classical piracy was for all intents and purposes a thing of the past by the arrival of the steam age, owing to the superiority and reach of European navies (and those "pirates" that did operate were largely functioning on a small scale in areas quite some distance from the high technology areas of the West). Because of this, there are likely no period images of "steam age pirates" to reference, and one faces the problem of how to adapt the pirate (by requirement a non-industrial individual) with the advanced industrial technology of steampunk.

My advice is simply to dress in the manner of a steampunk aristocrat or naval officer, perhaps substituting bulky gowns for men's garments for the sake of utility. That would be perhaps the easiest way to re-imagine a pirate in a Victorian context. And besides, women look quite charming in frock coats. That will probably be the easiest way to adapt the classical pirate to the demands of the Victorian period.

Regards, etc.,
-G. D. Falksen

Exactly! :-)

I second or third or whatever the thought of wearing a collared shirt that doesn't show much skin and a coat of some type. My wife typically wears bloomers and her long skirts. She tucks one part or two parts into her belt depending on how she's feeling and how hot it is.

Otherwise accessories just your typical pirate stuff with a steampunk flair.

Please take pictures when you get it done, my wife is always looking for more ideas.

http://damselinthisdress.etsy.com has some lovely corsetty waistcoats from time to time, along with boned "pirate coats" based on corset/bodice designs. My personal favorites, which she doesn't seem to have any of at present, are the cincher-under-short-waistcoat-with-tails variety.

Thankyou all for your advice! I've decided to go with breeches/pantaloons instead of a skirt, with boots, and a corset with high collar shirt, brooch, and big sleeves. :]