Diesel engined boat fire

[RCGrootveld]

UN Dangerous goods codes, as used on tank trucks / RR wagons (at least on the continent):

Diesel: 30
PetroL: 33

First mark: 3 > Flamable liquid
Second mk: 0 > Not specified
3 > Risk of ignition

So .......

A real (non sailing) ship is powered by steam, with diesel as the only alternative........

 

[Its_Only_Money]

[ QUOTE ]
There's more energy in diesel than in petrol, but the fire / ignition temperatures are VERY different.

Petrol:
Flash point: >45 °C
Autoignition temperature: 246 °C

Diesel:
Flash point: >62 °C
Autoignition temperature: 210 °C

So it is more difficult to get diesel to catch fire but, when heated, diesel ignites spontaneously at a lower temperature

Flash point is the lowest temperature at which a flammable liquid will mix with air and can catch fire.

Autoignition point is the temperature at which a flammable liquid will ignite of its own jolly accord.

(given normal atmospheric pressure and composition)

[/ QUOTE ]

I'm a bit lost at the chemistry bit, why do petrol fires occur outside the tropics then where the temp is <45 °C, this statement seems to mean that petrol can't mix with air until the flashpoint temp is reached??? /forums/images/graemlins/confused.gif

 

[andy_wilson]

Petrol power

Whilst on the subject of petroleum vapours, I trust you do not / will not travel on a boat with a gas installation because LPG cannot get away either, and it is far more difficult to spot or smell a leak?

Do you also ensure you do not moor alongside a petrol boat in case it blows your windows in?

 

[ArthurWood]

My original point, in my last sentence of the post was that statistically, at least in the US, most boat fires are caused by electrical faults. Of course, petrol will burn/explode more readily if vapor is escaping. Regarding safety, meaning reliability, on each group cruise I've been on over here, the most unreliable and very big and expensive boats have been diesel powered. But I guess this could be argued till the cows come home. I have petrols because I never considered diesels when I bought the boat a long time ago. If I were to change boats, I would go for diesel for running costs and range, but I'm not convinced about reliability.

 

[hlb]

If there was any arguement on the facts, then at least some trucks would run on petrol. Not sure about over the dark side. But nothing here runs on anything other than diesel. No ones ever heard of a petrol powered trawler, or battle ship for that matter. Petrol has little going for it, except engines are cheap to produce (small ones) and they have much more freedom of revs. Not required on a boat. Less towing skiers. Modern diesel are very fast and quiet. Though there is much to be said for the older simpler engines, where little could go wrong. However with everything, it's the installation that can go wrong. A badly installed diesel or petrol. Will still have problems.

 

[ArthurWood]

Haydn - here on the "dark side" there is a very good argument for petrols, at least for boats up to ~40ft: cost. For a boat the size of ours with 2x330hp, the initial outlay with diesels would have been be at least $50K more than we paid 12 yr ago. And with petrol at $3.59/imp gal I can buy a lot of petrol for $50K. Over those years, I suppose the cost of a gallon has averaged more like $2.00 or evn less, so we are past the break-even point, I grant you. Yes, diesels go on and on and on, but at 12 .5 yr old and 1500 hr our boat still runs fine on her twin Mercs. We have only been let down once by engine failure and that was something very minor once it was figured out.

 

[ArthurWood]

[ QUOTE ]
This is true if you drop a match into a bucket of diesel it will extinguish the match. If you dropped it in a bucket of petrol you'd be dead!

[/ QUOTE ]

Probably not unless there is petrol on your clothing, but if you're close enough to a bucket of petrol, especially on a warm day, to be able to drop a lighted match into it, simply striking the match would probably be enough to ignite the vapour. Try throwing petrol from a can onto a bonfire (well don't, under any circumstances) and the flame will jump to the can. Something to do with flame propagation velocity if I remember rightly.

 

[MapisM]

Interesting viewpoint.
The initial cost difference does matter for sure, which can be worth or not depending on the boat usage.
But aside from that, here in the med I dare to say that selling a 40' with petrol engines is a close-to-impossible mission for any broker.
Even in performance boats, diesel is becoming the rule rather than the exception...

 

[ArthurWood]

Mario - I'm well aware of the differences between the US and Europe regarding the Euro preference for diesels, both on the water and on the road. You hardly ever see a diesel car here and indeed some largish vans like the Fedex local delivery ones are petrol. It really comes down to capital and running costs over here which are much different from over there.
I think also that when it comes to cars, there is still some stigma attached to diesels in the US and not the acceptance/realisation that they have come a long way in terms of performance, cleanliness and quietness.