wjb21ndtown

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.

RT930turbo

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.

Budman II

iTrader: (1)

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.

Ryan8886

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.

endeavour32

iTrader: (4)

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.

Uncle Dave

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

endeavour32

iTrader: (4)

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.

Uncle Dave

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