Did you have a particular boat in mind ?, if you do I might be able to find it in the mountain of magazines on my desk.

2500rpm? that's somewhere between "dock" and "drive" on the throttle switch isn't it?:D

Gas Mileage
 

Bobcatmathews- Yes, a 40 Hustler with (2) 500s. If you can find a test. Years ago Powerboat tested a triple with 454/365s and the boat got somewhere around 1.6mpg. I was wondering how the 40 does with twins.
My 38 SC gets 1.1mpg.

I can tell you my experience.

My 46 cig with triple 575s, used 1.5 gallon per mile, running about 70 mph, 4100 rpm. on a long trip.

My 46 OL, twin 1075s, with smart craft has mpg displayed. Yesterday I was checking it out:

Idling .89 mpg.
3000 rpm about 50 mph 1.15 mpg.
3600 rpm about 60 mph about 1.1 mpg,
then about 4100 rpm at about 75 mph get about .90 mpg.

I didn't check out WOT ( I am usually looking over the windshield then ), but my average for the most outings is about .86 mpg.

I,ll look then get back to you.probably tomorrow morning,drinking beer and watching cubs vs cardinals right now (in spanish,on fox,and i do not speak spanish):D

The '41 Sutphen w/ Lambo's got 0.5 mpg (If you were nice) :p

Thats incredible with that much HP.

I got 4/10 mpg with my 2000Tiger and 700's

The 28' Active Thunder we owned for a while that was equipped with twin 350MagMPI's/Bravos consistently delivered over 2mpg at cruise speeds. If I recall correctly, this was 3300-3500RPM @ 50 +/- mph. It could do nearly 2.5mpg if pulled back to 3000.
I've talked to owners with the same package i.e. 29' Fountain and their results were the same. We enjoyed the hell out of that boat and its miserly fuel drinking tendencies. We had owned twin SBC boats prior with carbs, and the MPI made all the difference in the world in comparison.

mileage
 

35 Cig with 509's gets about 1 mpg as long as it's under 3300 rpm,over that and forget about it,,,,but who's counting.!!!

I loked through all of the mags I have ,and the only hustler test was in speedboat november 2006, and it was on a 44' magnum, with twin 750 eickert's. 0.8 mpg up to 2000 rpm 0.9 thru to 4000, and 0.8 to 5000 rpm.