I don't think it is quite ready for prime time yet but here is an
interesting idea. A small retractable Voith-Schneider drive like those
used on modern tugs. Retracts flat into the hull and when extended will
deliver thrust in any direction. http://www.spw-gmbh.de/en/hb/

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com