Petrol in boats

[MtB]

Now the installation of my Kelvin K1 is nearing completion, I'm wondering why petrol in boats seems to be considered such a risk.

 

In decades gone by I've understood the problem to be bilges full of leaked LPG being ignited by the ignition system fitted to run-of-the-mill petrol engines and exploding. This does not appear to me to be a risk associated with my petrol-start Kelvin as I'm not planning to start it should I find my boat full of propane. However I've read various arcane references on here recently to how risky it is to store petrol on a boat at all, so now I'm puzzled.

 

I'll be needing to keep petrol on the boat in future for starting the Kelvin, so can anybody explain the problem(s) with storing petrol on a narrerbote please? And perhaps point out the precautions I'll need to take to aviod killing myself (and my passengers) (and my neighbours)?

 

Many thanks.

 

Mike

[Paul Evans]

Petrol, unlike diesel, is extremely volatile. It evaporates at will and is extremely flammable. Petrol vapour can be ignited by a very small spark. Do I need to say more?

 

I'm sure that owners of petrol start engines will be along to tell you about the safety measures they take to avoid being fried to a crisp or blown to smithereens but you would do well to acquaint yourself with the requirements of the Boat Safety Scheme

[Tony Brooks]

Now the installation of my Kelvin K1 is nearing completion, I'm wondering why petrol in boats seems to be considered such a risk.

 

In decades gone by I've understood the problem to be bilges full of leaked LPG being ignited by the ignition system fitted to run-of-the-mill petrol engines and exploding. This does not appear to me to be a risk associated with my petrol-start Kelvin as I'm not planning to start it should I find my boat full of propane. However I've read various arcane references on here recently to how risky it is to store petrol on a boat at all, so now I'm puzzled.

 

I'll be needing to keep petrol on the boat in future for starting the Kelvin, so can anybody explain the problem(s) with storing petrol on a narrerbote please? And perhaps point out the precautions I'll need to take to aviod killing myself (and my passengers) (and my neighbours)?

 

Many thanks.

 

Mike

 

I suspect the most dangerous time will be when you are filling the starting system (not that I know much about Kelvins) because that is when there is maximum chance for petrol fumes to fall into the bilge. However I suspect the total petrol in use will be small. I would say guard against petrol fumes falling into the bilge. Do any decanting on the bank (and away from flames & sparks). Store the bulk supply on the roof or in the gas tank so fumes fall overboard. The RR answer would be a dedicated petrol locker built to gas-tank standards to hold the petrol can.

[MtB]

Petrol, unlike diesel, is extremely volatile. It evaporates at will and is extremely flammable. Petrol vapour can be ignited by a very small spark. Do I need to say more?

 

Well yes please, do explain. That was the whole point of my post. Petrol vapour AIUI is lighter than air so just floats away so what's the Big Risk?

 

 

I'm sure that owners of petrol start engines will be along to tell you about the safety measures they take to avoid being fried to a crisp or blown to smithereens but you would do well to acquaint yourself with the requirements of the Boat Safety Scheme

 

I'll take that as a 'don't know' then. Thanks.

 

Mike

[carlt]

 

I'm sure that owners of petrol start engines will be along to tell you about the safety measures they take to avoid being fried to a crisp or blown to smithereens but you would do well to acquaint yourself with the requirements of the Boat Safety Scheme

Your petrol should be stored in a locker, just the same as that other extremely flammable stuff, found on most boats, LPG.

 

Personally I am happy to have, correctly stored, petrol on my boat but don't have any LPG.

[PhilR]

I presume you will only be storing small quantities of petrol to start the Kelvin. The best place to store this will be in your gas locker if you have room.

 

Precautions? .......... the most important thing if you are decanting petrol from one container to another is to always do it off the boat on the towpath. Do you have one of the original Kelvin priming containers?

[NB Alnwick]

Now the installation of my Kelvin K1 is nearing completion, I'm wondering why petrol in boats seems to be considered such a risk.

 

In decades gone by I've understood the problem to be bilges full of leaked LPG being ignited by the ignition system fitted to run-of-the-mill petrol engines and exploding. This does not appear to me to be a risk associated with my petrol-start Kelvin as I'm not planning to start it should I find my boat full of propane. However I've read various arcane references on here recently to how risky it is to store petrol on a boat at all, so now I'm puzzled.

 

I'll be needing to keep petrol on the boat in future for starting the Kelvin, so can anybody explain the problem(s) with storing petrol on a narrerbote please? And perhaps point out the precautions I'll need to take to aviod killing myself (and my passengers) (and my neighbours)?

 

Many thanks.

 

Mike

 

As a liquid, petrol is highly inflammable so the usual precautions should be taken i.e. keep it in a suitable sealed container and keep it well away from sources of heat or ignition. As vapour petrol is extremely volatile. It is heavier than air so may not escape easily from a boat. When mixed with air, petrol vapour becomes a dangerous explosive and the slightest spark could trigger a violent explosion. When petrol powered boats were popular, they often had forced ventilation through the bilges in an attempt to prevent a build up of potentially explosive gases - nevertheless, explosions did occur . . .

[MtB]

I suspect the most dangerous time will be when you are filling the starting system (not that I know much about Kelvins) because that is when there is maximum chance for petrol fumes to fall into the bilge. However I suspect the total petrol in use will be small. I would say guard against petrol fumes falling into the bilge. Do any decanting on the bank (and away from flames & sparks). Store the bulk supply on the roof or in the gas tank so fumes fall overboard. The RR answer would be a dedicated petrol locker built to gas-tank standards to hold the petrol can.

 

 

Ah thanks Tony, so petrol vapour is like LPG vapour and heavier than air. That explains a lot.

 

Decanting petrol into the manual-fill carb can only be done inside the boat naturally, but I'll take care to decant petrol into the measuring jug in the open then. Thanks.

 

Any problem with storing petrol in the gas locker? No doubt it's illegal but is there any practical reason not to, given gas lockers have a drain to outside?

 

 

Mike

[Paul Evans]

Well yes please, do explain. That was the whole point of my post. Petrol vapour AIUI is lighter than air so just floats away so what's the Big Risk?

 

I'll take that as a 'don't know' then. Thanks.

 

Mike

If you decant petrol in a confined or unventilated space there is a high risk of the vapour igniting and flashing over to the supply you are holding in your hand.

 

I don't know about Kelvins but I do know the BSS places stringent requirements on the storage and use of petrol in boats - for very good reasons. Don't be an ass!

Edited September 7, 2010 by Paul Evans

[carlt]

It is lighter than air

No, it is about 3 times heavier than air.

Don't be an ass!

Asking the relevant questions seems to prove he isn't an ass.

[MtB]

I presume you will only be storing small quantities of petrol to start the Kelvin. The best place to store this will be in your gas locker if you have room.

 

Precautions? .......... the most important thing if you are decanting petrol from one container to another is to always do it off the boat on the towpath. Do you have one of the original Kelvin priming containers?

 

 

Hmmm no, but I'd LOVE to find one of those! Do you have one for sale by any chance?!

 

But seriously, being a plumber and reasonably capable at crafting copper sheet, I'm wondering about making one. Does anybody have any details of the internal construction so I can reproduce one?

 

Cheers, Mike

[carlt]

 

Any problem with storing petrol in the gas locker? No doubt it's illegal but is there any practical reason not to, given gas lockers have a drain to outside?

I can't see any reason that it can't be stored in the gas locker...The storage requirements are the same.

[MtB]

If you decant petrol in a confined or unventilated space there is a high risk of the vapour igniting and flashing over to the supply you are holding in your hand.

 

Ok thanks for your reply. Can you explain how the petrol vapour might ignite during decanting please? I really don't see this as a risk but I'm keen to be educated.

 

 

I don't know about Kelvins but I do know the BSS places stringent requirements on the storage and use of petrol in boats - for very good reasons. Don't be an ass!

 

So you don't know the reasons either then.....

 

 

Mike

[ymu]

Boats which run on petrol usually have bilge fans to clear vapour, I think. Would be a sensible precaution.

[5thHorseman]

Petrol has a flash point below minus 43C whereas diesel has a flash point above 60C so the potential for explosion from fumes is greatly enhanced with petrol.

 

I could not find anything in the BSS regulations about not storing petrol in the gas locker but I did find that there are requirements concerning the quantity, type of storage container and the marking of the container in the regulations. Can I suggest you read through the BSS (as I may have missed something). It is downloadable in .pdf format here linky

 

also there is a further explanation on the nature of fuels to be found here Linky2

 

HTH

 

edited: to add second link

 

5th

Edited September 7, 2010 by 5thHorseman

[Québec]

This BSS 2-page leaflet is also useful

Link

[MtB]

Petrol has a flash point below minus 43C whereas diesel has a flash point above 60C so the potential for explosion from fumes is greatly enhanced with petrol.

 

I could not find anything in the BSS regulations about not storing petrol in the gas locker but I did find that there are requirements concerning the quantity, type of storage container and the marking of the container in the regulations. Can I suggest you read through the BSS (as I may have missed something). It is downloadable in .pdf format here linky

 

also there is a further explanation on the nature of fuels to be found here Linky2

 

HTH

 

edited: to add second link

 

5th

 

 

Thanks for the BSS links 5thHorseman and Québec. I'm trying to understand the nature of the risk rather than blindly follow regulations, so I didn't consult them initially. Compliance with regulations does not satisfy my need to understand why they are there!

 

Even so, the very clear explanation of the risk presented by petrol in the link you gave 'appendix A - Nature of fuels' is exactly the information I was looking for. Thank you. So clear in fact, it's worth quoting here:

 

" B ) petrol

 

Petrol evaporates easily and quickly to the atmosphere to give rise to

extremely flammable vapours. The vapours given off are three to four times

heavier than air. They sink to the lowest level of their surroundings and will

accumulate at low level in places such as pits, depressions, the hulls of

boats or in enclosed spaces such as the cabins and cockpits of boats.

 

For petrol vapour to ignite in air, the mixture of vapours must fall within

certain concentrations; defined as the upper and lower explosive limits. For

petrol concentrations below 1.4%, in air the mixture is too lean to ignite, and

for those above 7.6% too rich; at all concentrations between these two

limits, a mixture of petrol vapour and air will burn. Hence whenever petrol

vapours are released, although they may be too rich initially to burn, they will

always pass through the flammable range to give a mixture that is capable

of being ignited before they are eventually diluted to safe levels. How long

flammable concentrations of vapours persist and how far they travel before

being diluted to a safe level will depend on the rate of release of the

vapours and the level of ventilation acting to disperse them.

 

Petrol vapours will not only be released from any spilt product but, because of

the ease with which it evaporates, they are released in significant quantities

whenever petrol is handled, dispensed or transferred from one container to

another. As a consequence of the flammable limits, petrol vapour when

diluted 70 fold with air will still give rise to a flammable mixture and it can be

calculated that one litre of petrol can, on evaporation, give rise to proximately

15 cubic metres of a flammable petrol/air mixture.

 

[source letter dated 25 September 1997 from HSE Principle Inspector John Hazledean]"

 

 

The BSS regulations focus on controlling the design of fixed storage tanks, piping etc. The way petrol is used in starting a Kelvin engine appears to fall wholly outside the regulations!

 

 

Mike

Edited September 8, 2010 by Mike the Boilerman

[JonL]

As a petrol engined boat owner, I agree petrol is more dangerous than diesel, however as with a lot of things in life it just comes down to common sense once you know that. Most accidents involving petrol normally involve people just being plan stupid.

 

A classic example was when I bought my boat the previous owner stored petrol in one of those emergency only £3.99 in every garage plastic containers, it was half-full blown up with petrol vapours to some wierd shape and stored, wait for it, in the same locker as the battery

 

Read the guidance, keep your fuel system well maintaned, run your bilge blowers everytime before starting and never transfer petrol about on board and you will only have a tiny risk of ever having problems.

 

Edited because I can't spell !

Edited September 8, 2010 by JonL

[nb Innisfree]

When filling a container leave sufficient air space to allow for expansion. Also we keep our petrol in a spare gas locker and always run the genny until empty so that it contains no petrol.

 

 

It's because of petrol's narrow explosive range that more accidents don't occur, it's fairly safe but when the conditions are right (or should I say wrong!) then the results are catastrophic with massive amounts of energy being released.

[RLWP]

So, why are you planning to start the Kelvin on petrol, Mike? From what I remember a Kelvin will happily start on diesel

 

Richard

[MtB]

So, why are you planning to start the Kelvin on petrol, Mike? From what I remember a Kelvin will happily start on diesel

 

Richard

 

Hi Richard,

 

First start of the day!

 

Kelvins come in two versions. Petrol-start and diesel-start. The diesel-starts will certinly start straight to diesel from cold but not the petrol-start versions. This can be got around by fitting a Lucas Thermostart, but ours is a petrol start without a Thermostart.

 

I'm expecting to be able to start it straight to diesel once hot using the electric starter but it's far kinder to the engine to start it on petrol from cold, even if it turns out to be possible to start it straight it to diesel with or without a Thermostart.

 

Anyway messing about with the petrol start is much more fun.

 

Cheers,

Mike

[RLWP]

Hi Richard,

 

First start of the day!

 

Kelvins come in two versions. Petrol-start and diesel-start. The diesel-starts will certinly start straight to diesel from cold but not the petrol-start versions. This can be got around by fitting a Lucas Thermostart, but ours is a petrol start without a Thermostart.

 

I'm expecting to be able to start it straight to diesel once hot using the electric starter but it's far kinder to the engine to start it on petrol from cold, even if it turns out to be possible to start it straight it to diesel with or without a Thermostart.

 

Anyway messing about with the petrol start is much more fun.

 

Cheers,

Mike

 

Hmmm, I'd happily dispute the need to start on petrol having watched a petrol start Kelvin started on diesel only, but the "messing about is fun" bit is undeniable.

 

Go for it Mike

 

Richard

[rjasmith]

For a subject that must be extremely obscure for most CWDF members this does seem to have come up a fair bit recently! Great for us Kelvin owners though!

 

Just a few things I'd like to add, although I should say that my Kelvin starting/running experience is limited to a K2 on a trolley and a K3 in a wooden fishing boat.

 

The K2 is now in a part fitted Nb but won't be in action for a while yet.

 

For each petrol start of course only a tiny amount of petrol is needed (about a wine glass full into the carb bowl plus a few squirts of it from a suitable oil can type device into each cylinder priming cock). This is only needed for the first cold start of the day on engines fitted with electric start, once warm it should go every time as a diesel on the button. I only know of one engine (K2) in a Nb which has no electric start - so for these folks it's a petrol start by hand every time. They are undoubtedly very good at it!! Also the fishing boat K3 had no electric start. Perhaps there are a few other non electric starters still about?

 

Also the carb filling point and air inlet are protected with metal flame trap gauzes so once the carb is filled, the fuel inside is relatively safe from external flash ignition (same principle as the miners safety lamp). (Mike - presumably your K1 carb has its gauzes still intact?

 

I certainly plan to keep my starting petrol in a can in the "gas" locker but it will be a gas free boat so no conflict with having gas cylinders in there as well. Using the proper carb filling bottle (or a replica of one) should also help to avoid generation of significant vapour.

 

Maybe you've seen the other two recent threads where the "Kelvin bottle" came up - there was even a suggestion of a Supporters Group for said object (KBSG!).

 

Sounds like a few of us plan to make them out of various bits and pieces. At least two of us have seen or even used the real thing (I'm one). I can PM my rather rough and ready sketch of it if you are interested. I've already posted a couple of photos of the genuine article - did you see those?

 

Richard

[sueb]

Ok thanks for your reply. Can you explain how the petrol vapour might ignite during decanting please? I really don't see this as a risk but I'm keen to be educated.

 

 

 

 

So you don't know the reasons either then.....

 

 

Mike

Most petrol fires seem to start when other half decides to make a cup of tea whilst hubby plays.

Sue