CAn anyone tell me what the difference in fuel consumption between a 42' Fountain with (2) 525's vs. a 45' Sonic with (3) 500 efi's?

I can tell you my buddies 386 sonic with trip carb 500's uses about double the fuel of my 386 with twin 496's.

But you're comparing apples to oranges. What type of boating do you want? If you are overnighting you want the sonic. The fountian is 1/2 the size of the sonic, and probably considerably faster even with 1 less motor, definately cheaper to run, maybe not quite as smooth in big water.
So to over simplify, whats priority #1? Speed or Cabin comfort?

Triples are way more expensive no matter how you look at it. More oil to change, drives to service. fuel to burn.

You will get a lot more feed back with more info...Where or what waters your going to run on, trailering or not, rack or slip, spending overnites, and how fast do you want to cruise, or if you like to WOT it alot.
Knowing this might give you more pleasure owning the 45 over the 42.

I went from twins in a 38 to trips in the 442. I can tell you that I gave up roughly .5 miles per gal vs the twins. I love the trips from a reliability standpoint. I can plane on two if one goes down. I do my own minor maintenance so oil changes, filters, plugs are not that bad. I will probably not go back to twins after owning trips.

What about insurance increase for trips? I believe the companies do not like them.

Tripples always need more ,,esp. on a heavy boat like a sonic.

Insurance is higher with trips. I live in Florida, so we get slammed anyway. There are only two companies that will wrtie wind coverage and trips in Florida.

There is definitely less stress on the drives with trips vs. twins.

I have a 47 Fountain with triples. There are pros and cons. First, it is a big heavy boat, much larger than the 42. It either needs triples or big power twins to perform adequately. Twin drives would need to be 6's. My boat gets just over 1mpg cruising in the 50's but much lower than that WOT. The triples are actually much lower maintenance than big power twins looking at the maintenance schedules and costs. The drives take less stress as well; however, these statements are only true if you have the 45 sonic, 47 fountain, Black Thunder or other big heavy boats. If you can get a boat that performs well with modest power twins, you're better off from a fuel economy standpoint and overall cost (maintenance, winterization, insurance, etc.). As has already been entered on this thread, the most important factor is your desired type of boating. The cabin on the 42 fountain is dramatically smaller and not comfortable to spend a lot of time in. If that's less important and you only want to occasionally overnight, then it's a better choice.

I ****in told you !!!! Welcome to OSO BROTHER! you spend more time in the cooler than looking at fuel guages anyway,its only $1.45 a gallon now cheap ass!

42 fountain is all you................