Hi Dan: I think there's some flaws in your reasoning. If you are thinking that you can drive a 46' cabin cruiser at 12 -14 kts on one 270 HP gasoline engine economically, it just wont work. If you have 2 gas engines but you intend to just run on one, the situation's worse because you are dragging all that resistance of the other prop, rudder, strut around with you. If your boat is capable of 12-14 kts of more, then it is not a displacement hull and hence it will not achieve those 12-14 kts speeds w/o trying to push up on to plane. I would guess that at 12-14 kts you would be in the maximum INEFFICIENT speed. Not running at a displacement speed but not yet on plane. I would guess that at 12-14 kts you would be running that single 270 HP engine full throttle. I would guess that you would get about 1/2 MPG or less at that speed and you would be running her guts out. If you drop down to about 8 kts your theory might work but at that speed with a semi-displacement hull and dragging one non-operating propeller, the boat will track and handle like a drunk driver. If the boat has 2 gasoline engines, use them both at less throttle. The fuel mileage will be about the same and you will have a vessel that is manageable. The point of running at say 15 kts, if that is where your vessel gets up on plane, is that it more economical the 13 kts, where it is mushing along. Also, if you have 2 each 270 HP gasoline engines in a 46 ft boat, there is no way that vessel will get to 30 kts. I would guess a WOT max speed of maybe 20 kts. Cruising is probably about 15 kts (just on plane) and pottering along, enjoying the day, is probably about 10 kts. Joe & Debbie Engel Marine Computer Services & JRE Consulting, Inc. MV Freda Fly - 40' Tollycraft Tri-cabin Portland, OR -----Original Message----- From: Daniel Chapman [mailto:dchapman61447@yahoo.com] Sent: Thursday, August 30, 2001 6:20 AM To: Trawler World List Subject: TWL: Single vs. twin engines - fuel economy While surfing the Trawler world Archives I found references to Single vs Twin Diesel Engines. I am hoping you can shed light on the other side of the coin... Single vs twin Gas. I plan to purchase a midrange sedan cruiser with twin gas engines (Ugh!) The reason for that is because the model I like doesn't come with anything else. It's twin gas or look for some other type boat. I eventually realized that my objection to the twin gas boats was more of an objection to TWIN gas not just gas. Or to put it another way. A single gas engine at 270 hp pushing a 45' 26,000 lb vessel would offer quite acceptable performance (from a trawler perspective). I would be content to cruise at 12-14Kts with one gas engine enjoying the benefits of ease of fueling, low operating cost, low noise and greater fuel efficiency of just one engine. Here's the kicker...When I talk to brokers about this they just say WHAT! You would want to run a twin gas boat on just one engine? Are you crazy? Maybe I am supposed to want to drive a boat at 30Kts. Maybe I am supposed to want to burn 20+ gallons of gas per hour. Am I crazy for wanting a fuel efficient low-moderate speed single gas cruiser? Please advise if you can. -Dan > dchapman61447@yahoo.com > > __________________________________________________ > Do You Yahoo!? > Make international calls for as low as $.04/minute > with Yahoo! Messenger > http://phonecard.yahoo.com/ > __________________________________________________ Do You Yahoo!? Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger http://im.yahoo.com