Bad Fuel Milage

[SWFLHarborHopper]

I need some help here from my fellow boaters and/or mechanics. I've done the math and compared my fuel usage with what Maxum has listed for my boat and engine combination (1998 3000 SCR w/twin 4.3LX V6's, Bravo 2 drives).
Maxum specifies 10 GPH (for each 4.3L V6 engine) at a cruising speed of 26 mph. At that speed, I go through about 22 GPH for each engine (more than double the specified usage). Of course I understand that a full water tank, full gas tanks, and # of people on board will have a drastic effect on efficiency, but not more than double the specified fuel usage.
My question is, has anyone found a particular preventative maintenance item that really increases efficiency??? I am very good about PM-ing my boat, but maybe I've overlooked something. Could my carbs need adjustment or rebuild? It starts and runs fine. Neither engine runs rough at all. Any suggestions? One day out on the harbor, going maybe 50 miles total, burns $300 in fuel!!!!

[seapuppy]

welcome to the zoo.....well....boat does stand for break out another thousand....so..I guess your in the ball park....just kidding....but really...depending on load, water conditions, winds, trim etc....everything could more than double the fuel usage...however...try this ..empty the water tank..run it down to about a half a tank...and see what your mileage is then...another thing to think of ..boats have a way of gaining weight....and with v6's...it doesn't take alot to over load them...go on board your boat and start taking off things you don't need.......if you have 2 of everything...take one off.....the weight savings will be huge.....like an airplane...weight = fuel burn.....
the other suggestion before we talk about carbs ...what is the condition of props and hull...are the props dinged up???are the correct props.....do you store it in the water...is the hull clean and waxed or do you have hull paint on??...if it's dirty ...it will slow the boat down and cause excess drag...thus reduced fuel mileage.....
now for maintenance...did you do a full up tune up on both engines...timing set correctly??...plug gap correct????....with the engines running ...is the exhaust smell gas rich??....

there are so many variables and since I don't have eye's on target ...I'm only adding some suggestions and what I would check......

SP

[hybris1]

Pull your plugs and make sure they are a nice chocolate brown. If black, you may be rich. Your buning 44 GPH? That makes me feel better about my gas hog. I am burning about 20+ GPH on my 27' 5.7L single B2 drive.