What you are really trying to do is the longest power boat passage--not necessarilly a circumnavigation. A circumnavigation occurs when your inbound track crosses your outbound track. You can leave from the Straits of Florida, to Cape of good hope--and thence around the souther capes, not crossing the outbound track until you reach the Straits of Florida again--and rack up 25000 or so miles. If you start the circumnaviagtion in Montevideo Uruguay or Punta Arenas, Argentina, you can complete the circumnaviation of the earth by the Southern capes--in about 16,000 to 18,000 miles at 2.6 miles a gallon, saving 6,000 miles and approximately 2300 gallons or 13,846 lbs of fuel. Every lb of fuel less will make the boat more effecient. The wave making resistance of a long narrow hull is minimal--and perhaps the slide rule could find a balance when less power is necessary--if you can make the asumption that all of the way will be beam or following seas, very little power. Again I bring up the 60 footer, with 10 foot bream and a 35 hp engine which burned only one gallon an hour going across the Atlantic. One other point. Books which should be aboard every Voyager. Looking at this problem three very old publications are of great value: Pilot charts, Ocean Passages of the World--older editions are better since they have better depection of sailing and low power routes--mine is 1973 and Distances between Ports (available on line). Weather routing will be of some value--but 8 knots you pretty much have what you will get. For Ellan McArthur it is much more critical, since she really wants 25 to 30 knots of wind on the beam (and is now about 48 hours ahead of the record). Yes it is a fasinating exercise--and design. I would tend to draw from ultra light sail boat hull forms, for greater effeciency than pilot and life boats--these are very in effecient hull forms, which can also be made very seaworthy. The pilot boats and surf rescue boats are designed more to sit on station and run thru surf. You will want to be moving with the seas--and getting maximum push out of the waves--so a semi surfing hull form may be better. Again a speculation--since I raced canoe type fin keel boats and choose boats much more as you descibe for passages. I do like the Dashew concept--and as Ron says it will be interesting to see how it goes. I have cruised and raced on a 55 footer which is very light, but still has the sea worthyness of the long keel deeper draft boats. Inital power was 35 hp--about 7 knots. Next 50 hp and 9 knots, now 112 hp and 11 knots under power. Same hull, just slighty more power--and this is a sail boat--but with a dagger board--takeaway the dagger board, and mast, and you have this long range power boat. But that weight of fuel bothers me--and I would make all efforts to decrease it. Take care, Bob