Curriosity. What is a cat's MPG?

[serpa4]

What kind of fuel efficiency does a catamaran get in the 40-45 foot range at 6-8 knots and not full throttle? 4mpg, 8mpg, I have no idea.

[model 10]

Nor does anybody else. You need to use gallons per hour. Who knows which the wind blows or the current goes.

[StuM]

Depends on conditions, but in calm conditions:

Running both engines, I use about 7.5 litres per hour at around 7.5 knots. (3.8 mpg(US)?)
Running one engine, I use about 4 litre per hour at around 6 knots. (2.5 mpg(US)?)

[Oliver L.]

Serpa,

with one engine running at 1600 rpm we consume about 2 liters per hour and do 5 knots in moderate conditions. That would be about 9 mpg...

Oliver

[S/V Illusion]

Originally Posted by serpa4

What kind of fuel efficiency does a catamaran get in the 40-45 foot range at 6-8 knots and not full throttle? 4mpg, 8mpg, I have no idea.

10 mpg downstream.

-1 mpg upstream in a 9knot current.

[StuM]

Originally Posted by StuM

Depends on conditions, but in calm conditions:

Running both engines, I use about 7.5 litres per hour at around 7.5 knots. (3.8 mpg(US)?)
Running one engine, I use about 4 litre per hour at around 6 knots. (2.5 mpg(US)?)

Doh! Make that second one 5.7, not 2.5

[serpa4]

Not too bad. Seems better than a cruising cat.

[monte]

Lagoon 400 is about the same as stu

[2 squirrels]

I have some numbers for you based on our 10.4 m, displacement hull, cat launch; 'Kirita'. This is a Malcolm Tennant designed cat built to his 17:1 formula. Each hull must be 17 units long by 1 unit wide and have sharp entry with a flattened bottom aft. Cats built to Malcolm's formula can achieve good speeds with relatively small, economical, outboard motors. We have two 60 hp Yamahas. The 'sweet spot' is at 3,400 rpm where we get - in a no wind, no tide situation - 12 kt while burning 14.3 lt per hour. This gives us 1.2 lt per nm, or, the other way round, 0.8 nm per lt. With fuel costing, in NZ, about NZD 2.10 per lt, this works out at NZD 30 per hour or NZD 2.50 per nm. Hope this helps !

[Redreuben]

So who is measuring nautical miles and who is measuring land miles ?

[StuM]

Originally Posted by serpa4

Not too bad. Seems better than a cruising cat.

?? The Lagoon 470 /400 and Belize are cruising cats.

You can ignore S/V Illusions contribution - he has a 15 ton monohull.

[StuM]

Originally Posted by Redreuben

So who is measuring nautical miles and who is measuring land miles ?

Since we are all referencing knots, that would be nautical miles per US gallon .

[Mirage Gecko]

Originally Posted by Oliver L.

Serpa,

with one engine running at 1600 rpm we consume about 2 liters per hour and do 5 knots in moderate conditions. That would be about 9 mpg...

Oliver

5 knots at 1600 revs on one engine in moderate conditions seems quite impressive.What type of motors and props are you running.
I am flat out getting 5 knots with 2800 revs with one MD 2030 Volvo and standard props in good conditions while burning about 2 ltrs per hour.

[clownfishsydney]

We have an 11.3 metre (38 foot) cat, running one engine (which is what we do 99% of the time) we use 2.2 litres per hour at 2200 rpm which gives 6 knots in flat seas and no wind. Using both motors at same rpm doubles fuel use but only gives 1 to 0.5 knots extra.

[StuM]

Originally Posted by Mirage Gecko

5 knots at 1600 revs on one engine in moderate conditions seems quite impressive.What type of motors and props are you running.
I am flat out getting 5 knots with 2800 revs with one MD 2030 Volvo and standard props in good conditions while burning about 2 ltrs per hour.

5 knots on one engine is also about 2 lph for me, but that's about 2200 rpm on a Yanmar 40HP (3JH3E) with a fixed two blade prop.