This is serious!

[Dave]

I have a £10 bet with a mate of mine. He says that marine diesel engines
use 25% that of marine petrol engines.
i.e. one gallon in a diesel engine will take you 4 miles, one gallon in a
petrol engine will take you one mile.
Sounds like bollocks to me.

Comments please.

[jolly.green]

gallon a mile, mate i couldnt afford to warm the engine up if it was that
costly
Dave <day...@freeserve.co.uk> wrote in message
news:9hj2ro$c8o$1...@newsg2.svr.pol.co.uk...

[Dave]

He's not far off, that's one of the reasons that the Navy are changing over
to diesel outboards where possible.
And, you can use nice cheap red diesel in a boat.
Dave

jolly.green <jolly...@ntlworld.com> wrote in message
news:7g9%6.32761$QM1.5...@news2-win.server.ntlworld.com...

[Steve]

My outboard gives me almost 4 hours per gallon, which works out about 20mpg
at Broads cruising speeds, I doubt a diesel would improve that by a factor
of 4, however once you get into high hp and planing speeds there is a big
difference but I would say its not as high as your example.

Dave <day...@freeserve.co.uk> wrote in message
news:9hj2ro$c8o$1...@newsg2.svr.pol.co.uk...

[Chris Ferguson]

Sounds about right. Why do you think the commercial boats run on diesel?
Commercial, tax free red diesle is only about a pound a gallon. Couple that
with the economy it makes sense.
In Cornwall even commercial 'speedboats' used for trippers are diesel.
HTH
Chris

[Dave]

I can see why they use diesel as it is duty free and about a quarter the
cost. I also believe that diesel engines are far more economical. I still
cannot believe that petrol engines use FOUR TIMES as much fuel. Infact I
find it hard to believe that petrol engines use twice as much fuel.

Does anyone know of a web site that will give some facts and figures on the
subject?

Dave

Chris Ferguson <cfba...@cableinet.co.uk> wrote in message
news:i4r%6.38693$4i5.2...@news1.cableinet.net...

[Tinca]

Any news of the loss of red diesel - I gather only 3 countries in the
EEC have tax free diesels and moves are afoot to put a pollution tax on
it

-Tinca

[Nick]

In article <9hj2ro$c8o$1...@newsg2.svr.pol.co.uk>, Dave
<day...@freeserve.co.uk> writes

It depends on what you are comparing:

2 stroke petrol vs diesel?
4 stroke petrol vs diesel?
Road diesel vs red diesel?
mpg or cost per mile?

If you are looking at cost per mile then a marine diesel engine running
on marine diesel is easily 4 times more economical than a 2 stroke
petrol engine. But if you are looking at a 4 stroke petrol engine vs a
diesel engine and only looking at mpg, then there is nowhere near the
difference...

--

Nick

[Elaine Jakeman]

We had a birchwood 25 with twin!! volvo AQ115 petrols and used to run them
one engine there and the other back, to make the fuel usage lighter (hah!).
A trip from our moorings at Linton-On-Ouse to Leeds and back used £80 of
petrol.

Our seamaster 30 with a single 1.5 bmc diesel went to Hull and back for
about £20 and most of the fuel was used on the ruff passage back!

Not sure on the difference in milage but its not a lot different i dont
think, though there are more locks to stop at on the way to leeds

Nick <Ni...@nospam.demon.co.uk> wrote in message
news:k9MfZLAR...@greenhse.demon.co.uk...

[Steve]

Elaine Jakeman <Ela...@seamaster.screaming.net> wrote in message
news:9hqpp3$vmr$1...@news5.svr.pol.co.uk...

> We had a birchwood 25 with twin!! volvo AQ115 petrols and used to run them
> one engine there and the other back, to make the fuel usage lighter
(hah!).
> A trip from our moorings at Linton-On-Ouse to Leeds and back used £80 of
> petrol.
>
> Our seamaster 30 with a single 1.5 bmc diesel went to Hull and back for
> about £20 and most of the fuel was used on the ruff passage back!
>
> Not sure on the difference in milage but its not a lot different i dont
> think, though there are more locks to stop at on the way to leeds

Err. not really a good example, BMC 1.5 puts out 30 odd hp, the volvo's put
out 115hp!

[Elaine Jakeman]

very true, but with a speed restriction of 4 knots on canals and 8 knots on
the Ouse though York, what a waste of 85 bhp!

Steve <st...@nospamjcs.gb.net> wrote in message
news:994144998.15382.0...@news.demon.co.uk...

[Brian Runyard]

We're ok until 2007, then they intend looking at the situation again.

"Tinca" <cha...@docangle.demon.co.uk> wrote in message
news:0ULt8IAQ...@docangle.demon.co.uk...

[Brian Runyard]

If you're talking about cost per mile, it's probably about right, as marine
(red) diesel is approx, £1.00 per gallon.

"Dave" <day...@freeserve.co.uk> wrote in message
news:9hj2ro$c8o$1...@newsg2.svr.pol.co.uk...

[Dave]

No price doesn't come into it. The bet is simply on the actual amount of
fuel consumed.

He says a diesel will do four times the distance on a gallon. I say it will
do much less than four times the distance.

Who wins?

Dave

Brian Runyard <brun...@taz.dera.gov.uk> wrote in message
news:9hsemi$mfr$1...@trog.dera.gov.uk...

[Nick]

In article <9htapm$dcg$1...@news6.svr.pol.co.uk>, Dave
<day...@freeserve.co.uk> writes

>No price doesn't come into it. The bet is simply on the actual amount of
>fuel consumed.
>
>He says a diesel will do four times the distance on a gallon. I say it will
>do much less than four times the distance.
>
>Who wins?
>
>Dave

If its the same horsepower then you win as there is no way a diesel is
more than a little more economical than a petrol engine. All cars would
be diesel if it were 4 times better!!
--

Nick

[Dave]

> If its the same horsepower then you win as there is no way a diesel is
> more than a little more economical than a petrol engine. All cars would
> be diesel if it were 4 times better!!

That's why I risked a tenner on it!

Dave

[Chris Ferguson]

"Dave" <day...@freeserve.co.uk> wrote in message

news:9hukm8$h66$1...@newsg4.svr.pol.co.uk...

Further thoughts : this is very difficult to answer as you cannot compare
like with like, unless you have two identical hulls. The commercials
use diesel because
a) no excise duty
b) much less hazardous than petrol in a working environment
c) big commercial diesels really slog, real grunt at low revs
d) big diesels outlast petrol by a long way.
Anything over 20 feet is more economical in diesel, yes, riverboats run
small two stroke petrols, but a small diesel will run all week on a couple
of gallons.
The commercial speedboats that work out of Looe, Cornwall run 120 hp diesels
which give 35 knots at under 2000 revs and economy. They would need a pair
of 200 hp petrol outboards by comparison and fuels bills would be
astronomical.
Chris

[Russell Eberhardt]

On Sat, 30 Jun 2001 00:27:37 +0100, "Dave" <day...@freeserve.co.uk>
wrote:

Time for some facts.

When I studied my for my Yachtmaster exam I was taught that an inboard
marine diesel engine would use about one gallon per hour for every 20
hp produced and that an inboard petrol engine would use one gallon per
hour for every 10 hp produced. (Imperial not US gallons)

However the spec for a recent Caterpillar marine diesel quotes 0.351
lb/hour consumption which equates to about 28 bhp per gallon/hour so
efficiencies have improved somewhat.

I can't find any specs on modern inboard petrol engines (after all who
would want one?) but Nissan quote 1.1 gallons/hour (presumably US) for
a 10 hp 4stroke outboard and 1.5 gallons/hour for a 10 hp 2stroke
outboard.

Translating all into the same units we get:

Inboard diesel 28 bhp/gallon/hour
4 stroke petrol 11 bhp/gallon/hour
2 stroke petrol 8 bhp/gallon/hour

You still win. The difference is less than four to one but only just.

How many miles you get to the gallon (or how many gallons to the
mile!) depends on many factors. My boat does about one mile per
gallon of diesel.

Regards,
Russell.
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