I wasn't trying to be sarcastic. The bigger the boat,more powerful etc. the more fuel it is going to consume. I think what it comes down to is how big of a boat do you need? What accomidations do you need? How fast do you want to go? If you need a bigger boat for the type of boating you want to do then most likely your going into a twin engine no matter what. To get a bigger boat to go faster with one engine requires more power, more power uses more fuel so whats to be gained by one engine in a bigger boat? On the other hand if you don't need a bigger or faster boat then stop looking, you already have the boat that suits your needs. Sometimes we need to be happy with what we have already.

You'll find it will consume more gas, not by a huge amont though unless you are putting it to the wood constantly - but your drive components will live longer because they are sharing the load.

The maintenance isnt 2X,(only routine stuff is)

REAL maintenance its more like 4X because deferent things break at different intervals on each engine at different times- all at inconvenient times.

a single stout BB works better for me.

Uncle Dave

This has been my experience as well. Twins seem to be more efficient than a single. I've brought this up on a number of occasions - two boats cruising from Lake St. Clair to Put-in-Bay, one is a 26' Nova with twin 350s, one is a 21' Liberator with a single Ford 460. The Liberator used MORE gas to make the same trip at a cruising RPM. Wide open may be a different story, but we've never tested it.

Especially if your new boat is an EFI or MPI you will likely get better gas mileage up to around 45Mph, and the difference will be negligible at best after that speed.

The argument against twins should come down to maintenance, not gas consumption. Changing oil, filters, fuel separators, 16 plugs, two sets of wires, two drives to change the fluid in, gets pricey.

Not supercharged. Actually at same RPM the twin is about 5-7 mph faster. That being said, I can cruise at a much better clip at 3200 RPM with the formula than the cig. I think the biggest factor in the fuel economy is the fact that the single needed to spin harder to make a good cruise speed. I was constantly trying to "keep up with the group" and was in the 4000 RPM range most of the time. In the formula I can keep the revs down and the secondaries closed to achieve the same speeds.

Just my real world experience.

It sounds like you are comparing a High perf single to relatively stock twins, much like I was. I would agree that a single 454 mag vs twin 454 mags would be a different story.

Another thing to consider when dealing with a twin engine boat is not just cost of maintenance but ease of maintenance. If you cuss a blue streak gashing your knuckles changing those plugs on your single, then you will really weave a tapestry of obscenity when you have to squeeze in between those manifolds on a twin engine boat! Replace a starter on the port side? Fuggetaboudit! Time to pull an engine. Changing things like seawater pumps can be a beotch on a single engine boat, but it's a load of fun on a twin, especially if there is not much access room in front of the engines. Just something else to consider if you do your own work.

He ain't kidding about the cussing. However on the fuel end of the question...I average about 2 mpg around 45mph cruise speed at about 3500rpm with twin carbed 7.4's.

It seems that 2 mpg at cruise seems to be fairly common. Thats close to or better than I'm getting now with my 242.

I get about 2.5 at 45-55 and around 2.3 at 60, which I think is exceptional.

I have a medium weight 28.8 foot boat and a single but modern EFI 700 horse "big block."

Lets not forget about prop changes on twins.

Want to do double duty on your rig and use it as a toy tower or skiier-?

To do it well you are probably going to have to keep two sets of props and probably an identical spare for your 2 main wheels.



Uncle Dave

My 242 is too big for waterskiing, wakeboarding, ect, let alone a 292. Thats what friends are for. I'll go in their boats for that. One set of props is all I need.

I get it.

At the same time it depends on what you do.
On occasion I will pull a skier across the channel to Catalina in the ocean at speed.

Ill also tow a big inflatable full of kids across a 20 mile lake on the way to a campsite


Uncle Dave