Ah, that's what I thought it might be.
And the Finnish-english dictionary program -- which my employer has kindly provided me with, but I'd forgot I had; that's why I didn't use it yesterday -- concurs. Well, it doesn't have 'skeg' as a stand-alone word, but as part of the term "skeg of a keel", which it translates as "kölin kanta t. takimmainen osa". Unfortunately, Finnish isn't my first language either, so I'm not quite sure...
But our dept secretary, Annika, confirms my hunch that this means "the base or rear end of a keel"; so the makers of this dictionary don't seem to agree with your "orthodox definition" that it has to be under the center. Oh well, this thing sucks anyway: It doesn't have a translation for "wolverine" at all! (Trying to find that was how I remembered I had it in the first place. But Annika -- I ask her about language stuff at work, because like Linus T. she's a Finland-Swede and thus perfectly bilingual -- tells me it's "ahma".)
Uuhh... Sorry, I sem to have digressed a bit there... But anyway, to get back to the point: Why, sure you can have a skeg!
I planned on that myself, I think. And that's one more reason to go, at least at first, with the El Cheapo design alternative of using an off-the-shelf outboard engine in stead of futzing around with water jets and stuff: If you mount the ski the easiest way, making a hole in it and letting it slide up and down the vertical drive shaft, you get your skeg "for free"!
It'll be there already; outboard engines usually have a protruding fin below the propeller (presumably to protect the prop from hitting rocks or the bottom), don't they?
Christian R. Conrad
The Man Who Knows Fucking Everything