Patrick
Harbor models carries voith-schneider drives, They are a little pricey, but totally cool. I don't think they are very heavy duty and where they would be located would be too close to where you would have ice contact, but harbor models sells replacement blades, I have some diagrams from a guy that scratch built one out brass in the UK. I think the kontio would look the best with conventional drives or two 360 degree Z drives.
TUG