Come clean on fuel consumption

[saltwater_gypsy]

I have a 43ft sailing yacht which, under engine, consumes 3litres per hour at 6knots which gives 2miles per litre or approximately 10mpg.
I have been told that a 30ft motor yachts use 20litres per hour at 20knts which is approximately,1mile per litre or 5mpg.
What are typical figures for a displacement vessel capable of say 12knts?

 

[omega2]

Where is this frugal machine? I want one

 

[Deleted User YDKXO]

You've been told a porkie. A 30ft mobo at 20kts would consume fuel at 2-3 mpg
What length/weight of displacement boat?

 

[longjohnsilver]

A displacement vessel capable of 12kts would have to be at least 80' long. Not too many of those about.

 

[epervier]

[ QUOTE ]
I have a 43ft sailing yacht which, under engine, consumes 3litres per hour at 6knots which gives 2miles per litre or approximately 10mpg.
I have been told that a 30ft motor yachts use 20litres per hour at 20knts which is approximately,1mile per litre or 5mpg.
What are typical figures for a displacement vessel capable of say 12knts?

[/ QUOTE ]

[ QUOTE ]

Where is this frugal machine? I want one

[/ QUOTE ]

5 mpg I'll have two /forums/images/graemlins/grin.gif

 

[DoubleVision]

I`ll fess up! 2mpg at cruising revs on a 31footer with 460hp. ------ But I am doing 32 knots. /forums/images/graemlins/grin.gif

 

[epervier]

here's more of a clue, using old fashioned calculations, a diesel working flat out, or producing it's maximum, if you prefer, burns 1/2 pint of fuel per horse power,per hour

IE; in my case, for example, I have 2x 200hp engines, therefore I burn 100 pints of fuel per hour per engine, or 25 gallons an hour, my max SOG with full tanks bits and pieces for the weekend and four adults is 32 kts or approx 35 miles an hour, and an approx all up weight of 5 - 5,1/2 ton, divided by the 25 = 1.4 mpg.

By pulling off wot by 1000 rpm I achieve 22-24 kts but I really doubt if I'd get double the mileage of 2.8 mpg

nearly forgot, my craft is 31' long

hence my jib about 5mpg.

 

[[2068]]

My 29ft (almost) motor cruiser will consume more like 40 litres per hour at 22kts, which is approx 2.3mpg.

dv.

 

[hlb]

Dunno but if I get better than one mile to the gallon I'm happy. On the other hand, I get far better value for money at the other end, on mooring costs. Spend most of the day there, whilst the raggie arrives at midnight and leaves at six AM. For the same 20 or whatever squids. Also in the day, I can visit loads of places on the way to the next over night stop. Not all the hurrying along and making good time.

So the question about fuel used. is a bit questionabe.

 

[John100156]

OK - My Targa 34 with twin KAD300's (2 x 285 BHP) will do somewhere between 1.5 when opened up to 2.5 mpg when slow cruising. I would estimate 2500rpm at 22k, 3000rpm say 30k and 3,500rpm around 40k. Depends to some extent on conditions of course.

 

[nonitoo]

My 27' sports cruiser has a 200 hp 2.8 ltr Mercruiser diesel.

Supplied data gives WOT 3800 rpm consuming 46 ltr/hr (on my boat 28 knots).

At 3000 rpm consuming 22 ltrs/hr (on my boat 20 knots).

Guess which throttle setting I use ?

I have used these figures for two seasons and believe them to be reasonably accurate.

Tom

 

[mainshiptom]

My Mustang with Cummins qsc8.3 540 hp will do

A 2120rpm cruise at 18.6kts will consume 60lt/h per engine. A 2200rpm fast cruise at 23kts will consume 63.5lt/h per engine, while a 2670rpm top speed of 29.9kts will consume 105lt/h per engine.

A 600rpm cruise at 4.3 knots will consume 2.5lt/h per engine.
A 1000rpm cruise at 7.8 knots will consume 10lt/h per engine.

So you can burn loads and get some where very quick or cruise like a sailing boat in the direction you want to go for very little?

Tom

 

[omega2]

Had a log on our Aquabell Mediteranean 33, for 10 years now, never got better than 8 gallons an hour overall, weight is about 6 tons, so they tell me, pair of Sabre 180's, that will pull 2450 revs but rarely used,generally about 2150, cruise speed of 13/14 knots depending on tide. Semi displacement hull, and a joy to handle in any conditions except when getting in to the fuel pontoon.

 

[Seadee]

Ouch - often admired your boat but I wouldn't like to have to fill it up !! /forums/images/graemlins/blush.gif

I run a 8m MF805 with 200hp Nanni and all things considered I reckon she's using about 25L per hour at 15knots and 3,000rpm so that makes about 3mpg.

CD

 

[Paragon]

40' displacement trawler yacht, twin 120hp diesels giving 8-8.5 knots cruise using 3 gallons per hour!

/forums/images/graemlins/smile.gif

 

[LittleShip]

32' displacement

8-10 tons

6knts 1 1/2 gallons/hr

7.5knts 2 gallons/hr

WOT........... you must be joking!..... probably 8-9knts and 2.5 gallons

1000 mile range depending on weather conditions.

I have to say fuel consumption was not the reason for buying the boat, I had been a raggie for 20 some years and just wanted to be on the water "plodding" about. Rushing from one place to another is not for me I prefer to be on the water "plodding" not in the marina.

Tom

 

[2_XS_IF]

Raceboat No43, 32 ft long, 4mpg at 40mph and 2mpg at 60mph. 150 gallons of diesel, 600 mile range at 40mph, 300 miles at race speed. But no room for wife and kids.

 

[gjgm]

gallons..? goodness me; I ll need to ask my grandfather what that is.
From memory, according to Volvo/Windy, with twin Kad 300s,I should be getting between about 60-70 lph at about 25 knots up to about 120 lph at 43knots.
General underway, I think is at about 2.25 lpm, but its easily more...

 

[LittleShip]

No Beer storage
No where to make a cuppa
No sleeping accommodation
No Fridge
No TV-DVD
No sunbathing area
No fishing area
No Contest!
Sea fairing Whippet attack dogs would hate it
and probably only weighs about 1 ton

No contest I'll keep mine.
/forums/images/graemlins/smile.gif

Tom

 

[Kawasaki]

Gallons?
This is yer Granpappy talking.
3 1/2 Gallons an hour at 12 ter 13 knots.
27ft mobo with 105hp Green thinghy.