Georgs, My current project, 19m x 56,000#, yet to be launched, also has a pair of ~300hp engines. I'm expecting 2 mpg @ 10kn, 1 mpg @ 20kn. I'm sure Malcolm has extensive records of actual mileage figures. An advantage of the modern electronic diesel is the ability to run efficiently at the lower speed. Ideally contolable pitch props could be used as well, but I didn't want to spring for them. I will be able to freewheel one prop as long as the transmission temp is monitored. This mileage is probably comparable to larger trawlers whereas a small trawler, a Nordhavn 40 for instance, would get 3.75mpg @ 6kn, 2.6mpg @ 7kn, and 2mpg @ 8 kn. To me the question is more than miles per gallon; there's a whole raft of reasons to go with multihulls and performance is an important one. I'd go nuts making a passage at 6 knots. Bill ____________________________________________________________________________________ Need Mail bonding? Go to the Yahoo! Mail Q&A for great tips from Yahoo! Answers users. http://answers.yahoo.com/dir/?link=list&sid=396546091

Bill wrote: >My current project, 19m x 56,000#, yet to be launched, >also has a pair of ~300hp engines. I'm expecting 2 >mpg @ 10kn, 1 mpg @ 20kn. I'm old fashioned and tend to think in GPH (gallons per hour) for fuel burn. Thus, 2 miles per gallon at 10 knots = 5.00 gallons per hour 1 miles per gallon at 20 knots = 20.0 gallons per hour For ocean-crossing purposes, except in calm seas, I suspect you'll find the 10 knots much more appropriate. I believe Wild Wind IV, a Tennant-Raedeke-Pachoud 60-footer, crossed the Pacific burning 5.17 GPH while averaging 9.3 knots. That works out to 1.8 MPG. I don't have numbers at hand for a 60-to-70-foot monohull, but I do know a Nordhavn 47 just arrived in Gibraltar having burned 5.3 GPH, including genset and stabilzers, running at close to 7 knots across the Atlantic. An efficient displacement monohull in the 60-foot range running 9 knots like Wild Wind would probably burn closer to 10 GPH. So, the passagemaking power cat may have a slight advantage in fuel/speed efficiency. >To me the question is more than miles per gallon; >there's a whole raft of reasons to go with multihulls >and performance is an important one. I'm familiar with the reasons and I applaud and love them. In fact, I own a power cat. My point was that before ocean-crossing multihulls can attract buyers away from displacement trawler yachts, they will need to offer substantial improvement in speed and fuel burn. Which to me means boats like Globetrotter, not fat catamarans that perform only marginally better. I hate to appear to be wearing a black hat but I'm getting weary of hearing how wonderfully efficient as passagemakers power catamarans are. On paper, sure, but they still have to prove it in the real world while crossing oceans. Which only a handful have done. I wish you well, Bill, and look forward to hearing of your actual experience out there. --Georgs -- Georgs Kolesnikovs Power Catamaran World http://www.powercatamaranworld.com

Georgs, This is a little belated but I have only recently found out about "Chrysalis". The "handfull" gets bigger. There have now been 12 of our designs go seriously trans-ocean. The latest is "Chrysalis", a WildWind IV design. It has gone from Bermuda to the Azores enroute to the Mediteranean. They burned 2mpg at 9 knots and crossed in 8.5 days which was 5 days faster than some Nordhavns doing the same crossing. The fremantle "R&R" is travelling up the West Coast of Australia and is currently in Darwin. This doesn't qualify as transocean because they can always duck for cover if they have to but it promises to be a mighty trip just the same. Regards, Malcolm. MALCOLM TENNANT MULTIHULL DESIGN LTD PO Box 60513, Titirangi. Waitakere 0642 NEW ZEALAND Ph: +64 9 817 1988 e-mail: malcolm@tennantdesign.co.nz www.tennantdesign.co.nz www.catdesigners.com