catamaran which will weigh under 1000 pounds and have narrow 15 inch hulls. The hulls were designed for us by a world class hull designer. Our first prototype a with 21 foot hulls did over 50 mpg estimated economy. What outboard motors would you recommend for this boat. Desire light, fuel efficient and able to control from the console?
what outboards were on your prototype? or was the 50mpg a theoretical figure? At what speed did you attain 50mpg?
MPG is not really an applicable fuel rate measurement with a boat. Most will more likely understand economy in terms of litres per hour @ so many RPM and such and such a hull speed. There are planing hulls of around 20' fitted with a twin cylinder diesel of 20 odd HP that achieve economy around 2 ltrs per hour at a cruise of 16 knots - full speed 20 knots. The particular one I am thinking of is in the latest Wooden Boat magazine. 50 mpg is not a number that makes much sense with a boat unless you know what revs and what speed you are getting that at. It sounds wonderful, but as boats are used in a radically dynamic medium the number will be considered only achievable in perfect conditions. In practice boats can return fuel use figures as low as one third of optimum when the weather is bad. Yanmar no longer make the outboard diesels I am told, or they would be a very interesting choice for ultimate economy - heavy though. Yamaha make a very good product in the fourstrokes, but it must be said that all of the big manufacturers make a good product, with all the big names there really isn't a bad product as such. The smaller E-TEC Evinrudes - say the 50 HP is supposed to get about four times the economy at idle of the equivalent Yammie 50 4 st - I find that astonishing if true, but never having owned an E-TEC I can't say if that claim is real. I note that most commercial and govt. outboards are Yamaha. If I went back to commercial fishing Yamaha would be my first choice, but I would look at the E-TECs closely. There is a local charter operator who swears by his E-TECs, once the early teething troubles got sorted anyway. He has re-engined with the latest E-TECs and that says a fair bit to me. You might consider the smallest diesel saildrives - or even a single one in a central pod - if economy is the absolute goal. Sounds like an interesting project.
