Hypothetical situation here. I am always shopping and would like to know the answer to this question;

Lets say you have a 35' boat with a pair of 600s in it and you want to cruise down the lake for 50 miles at 70mph. Now lets say we have that same boat with a pair of 1100s in it and we want to do the same thing. Will the 1100 boat use more fuel? Less fuel? About the same? Might make a difference in my next purchase. Thanks

If you knew the bfsc at the respective engine speeds that they would be turning, we would have your answer. Otherwise it's impossible to know based on your inputs.

My take would be if you're AT ALL worried about fuel consumption than you have no business buying a boat with 1100's in it.....

flip side of that statement; if you can afford a boat with 1100's, and buy it, you have a duty to burn as much fuel as possible...

The 600 can be N/A and the 1100 is a safe assumption positive supercharger ?

The 1100 will be heavier than the 600, and the PD SC takes power to turn.

The 1100's will swing more propand use less gear ratio. Those will take more hp.

So....just breaking the surface with the subject, the 1100 will consume more fuel..everything else being equal.

Fuel is the least of my worries when I hit the happy stick/s

I guess you could argue that you would be able to run with less throttle on the boat with 1100's, but we both know that less throttle is not in the cards if you have something like that. Let's put it this way - if you had a 12 inch schlong, would you only use 6 inches of it?

But seriously, it takes a certain amount of power to do the work of moving that boat x miles at a particular speed. So it takes a certain amount of fuel to do it. It all comes down to which rig is running most efficiently at the RPM level it takes to get the work done.

Sometimes I have to use less. But this isn't the place to discuss this.

Your cruise speed with the 1100's would be much higher than same boat with 600's. You should not compare the two hp levels at the same speed, because the efficiency only comes from getting more boat up out of the water at a higher cruise speed.

So the 1100hp version could cruise at 80+ mph without making any boost and have less wetted surface friction to overcome at the higher cruise speed. Your gallons per hour may be higher than the 600hp package, but your miles per gallon may in fact be higher with the 1100hp package- until you put the motors into boost.

You sure about that, SB? Seems like we have a dik-measuring contest about every other day on this site lately!