Single vs Twin

[JimK]

I am trying to settle a friendly bet. I suspect this topic has been discussed in the past but could not find anything conclusive. Forgive me in advance for such an elementary question. In a given boat that is available in a single or twin engine configuration (say an F28 0r F30), is the fuel consumption the same at cruising speed on both configurations or does the twin consume more?

[7421f]

In my 11 meter express and I suspect all twin engine boats, if I shut one engine down, I burn about 1/2 of what both engines combined burn, according to my FloScans. There is a slight increase in fuel consumption on the operating engine as it has to work a bit harder. I do loose speed at the same RPM setting. So, to answer your question, twins are going to use substantially more fuel, not to mention at least twice the maintenance costs over a single engine.

[kenflyer]

I agree with Tim based upon my personal experience with twin engines. However, I have been told by more than one mechanic that i should not run one engine. I haven't experienced any problems doing so. I do like the handling of twins in close quarters given their ability to turn and turn on a dime with one engine control in forward and one engine control in reverse

[todd brinkerhoff]

The same boat with the option of single and twin will usually involve smaller twin engines (ie small block) vs a bigger single engine (ie big block). In that situation the fuel consumption difference wouldn't be dramatically different. As Tim said, repair costs would be double.

[prowlersfish]

The single engine boat will be some what better on fuel ,more so at under hull speed .Mainly do to less drag / fiction . I would prefer a single engine myself .Maybe the next time

[captainmaniac]

Twins will consume more, but not 'substantially' as has been posted. Increased horsepower with twins will take more fuel, but if a single doesn't have enough power to push the boat you are either running at very low speeds or stressing the engine big time. You will pay for the fuel it takes to feed the horses you are running.

With my F32 (16000 lbs loaded) with twin Chrysler 360s, I average 1.1 mpg. My father's old wooden 28 footer (6600 lbs) with a single Chrysler 383 mileage averaged almost 2 mpg. Less than half the weight, more than half the fuel burn.