anybody got any idea about the fuel comsumption of three motors vs two?will the three motor boat use more gas all the time,vers a two motor boat with the same h/p rateings.a guy was trying to tell me that a 42-47 fountain will get better fuel comsumption w/three 502's vs the same boat w/twin 600's or 700's.any input?

Its possible. My 32 AT with twin 502mpi's get better mileage at cruise speeds than my single hopped up 525SC 28 Pantera did.

A hull design will take X amount of horesepower to power the boat forward at a given speed. Ideally that horsepower is devided between how many engines you have. But there is the increase amount of drag in the water from an additional drive an weight increase. Potentially 3 engines could deliver the needed horsepower lower in there RPM range at a point where they are more fuel efficient than the same boat with twins.

I like the idea of a 47'er having three 525's strictly for reliability sake if for no other.

If the 3rd engine can allow you to cruise under 3500 you will have a fuel saving

Fuel consumption is relative to how much horsepower you're making. There are conditions where you would use less TOTAL horsepower with the triples and get better fuel efficiency.

I love triple engine boats. I had a 40' Hustler w/3 502 Mag 415s.

There are other advantages to trips:

You can lose one engine and still get home on plane at a good speed. (I blew away Stu Jones when I ran most of a Poker Run on two engines)!

Instant planing. Never have that bow up situation that limits visibility until planing speed is met.

Boat flies level with the center engine so far forward.

The down-side is buying oil, filters, spark plugs and belts for three engines rather than two. Still worth it.

The downside is less efficiency. Running the output through two drivelines vs. 3 is an advantage. Plus the drag loss of the 3'rd drive and prop slip all have to be factored in. Plus, there's the fact that you're carrying around an additional 1,000 lbs (and that's conservative- allowing for additional hardware on the twins, like blowers.)

There are plusses & minuses- and mostly it's dependent on the individual boat. I think that a larger boat would be more forgiving of triples vs. a smaller one.

so are you guys telling me you can use either 2 motors or three when running.i was under the impression that you have to use 3 motors all the time??

If you want to run on just two, you're going to have to jump in and yank the prop on that center drive.

You don't have to yank the center prop. Sure you could pull the prop to reduce drag but it is not necessary.

I have trip 496's and my boat it will plane on any combination of the two. I blew a drive on the port side halfway between Key West and Sanibel. I was actually on my way back to Tampa and continued on, but Sanibel was a fuel stop on the way back. I ran the port engine at idle and left it in neutral so the hydraulic steering worked properly. It is a little harder to get on plane but not a big issue and can still cruise about 40-45 on two. I have had trips for four years and find more positives than negatives to having them.

I remember my 38 with twins and when one went down, you better hope and pray you are not 40 miles from your destination as you are not going to get on plane.

I agree that maintenance costs are higher but since I do most of the maintenance myself, it is negligible.

I would definitely go trips on my next boat.