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Old 09-07-2016, 07:11 PM   #41
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Gas vapors do indeed drop because they are heavier than air. Air has a weight density of 1 and gas vapors have a weight density of between 3 and 4. Vapor densities less than 1 will rise and greater than 1 will fall. The problem with carrying gas on board a diesel powered boat is that if there is any small gas spill or leak, the vapors can travel down into the boat causing a potential explosive situation. Vapors can travel a lot farther than one might think. Most diesel powered boats do not have ignition protected components installed in them because they are generally not required on a diesel boat. Most diesel powered boats do not have ignition protected bilge blowers either so if you do get some gas vapors down into the bilge, how do you get them out without blowing up the boat? When we carry gas for the dinghy, we either leave it in the dinghy on the swim platform brackets or strap it down on the swim platform. That way if any vapors get out of the tank, they will drop down to the surface of the water and dissipate without any problem. If you do carry gas inside the boat or up on deck/flybridge you should look at the potential paths that the vapors could take into the boat. If there are paths that lead into the boat, find another place to store the gas.
Really interesting catch.I wonder why abyc,or ul,or some other governing agencies haven't caught onto that.Since the vapors will settle lower,where the diesels are,and if given the opportunity to get below deck(open hatch or such),and there are no ignition protection devices to be found,doesnt that present itself as a possibility of an explosion?It is common place for those with dinghies to carry gas.Surprised that they are not requiring some sort of a vaportight,or explosion proof enclosure.
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Old 09-07-2016, 08:02 PM   #42
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Oh come on. Gas vapors escaping a container, in the open, drifting down and collecting into the bilge and exceeding the LEL? It'd be more concerned about secondary containment where fumes can collect.
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Old 09-07-2016, 08:12 PM   #43
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My engine compartment's ventilation system is primarily to provide air to run the diesel engine. While there is an exhaust fan, it's at the top of the compartment, and it's purpose (seldom used) is primarily to draw in fresh/cool air after the engine's shut-down. So, I wouldn't want to locate gasoline storage within the boat. If I had a gasoline need, I'd place the fuel outside in a location where the heavy vapors wouldn't leak into the boat.
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Old 09-07-2016, 09:02 PM   #44
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Greetings,
Mr. LM. " It'd be more concerned about secondary containment where fumes can collect." As described in post #21 perhaps? Maybe Mr. Rekindle can explain his reasoning for storing his gasoline as he does. I'm curious...
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Old 09-07-2016, 10:12 PM   #45
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Oh come on. Gas vapors escaping a container, in the open, drifting down and collecting into the bilge and exceeding the LEL? It'd be more concerned about secondary containment where fumes can collect.
Please refer to post nine,so yes it can happen.One report of something like this occurring and causing an explosion would cause all these governing bodies to scramble for a preventative measures.Likely not to occur,low odds probability ,I agree.But safety measures aren't only deployed after a catastrophie,sometimes ,someone is smart enough to think about it before.But are odds probability really the appropriate way to measure possibly saving maybe one persons life,i think not.
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Old 09-07-2016, 11:21 PM   #46
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In reference to #42 post, I never said it was likely, but that it was possible to get vapors inside the boat from a gas tank on deck or on the bridge. If the chance is 1 in a 100 or 1 in a 1000, I would not want to be the 1. I am just saying that I would never store gas onboard a diesel boat, but rather keep it down on the swim platform either in the dinghy or on the platform itself. I once saw a gas powered boat explode due to gas vapors in the bilge, I never want to see another and particularly don't want to be onboard when it happens.
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Old 09-08-2016, 07:17 AM   #47
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In reference to #42 post, I never said it was likely, but that it was possible to get vapors inside the boat from a gas tank on deck or on the bridge. If the chance is 1 in a 100 or 1 in a 1000, I would not want to be the 1. I am just saying that I would never store gas onboard a diesel boat, but rather keep it down on the swim platform either in the dinghy or on the platform itself. I once saw a gas powered boat explode due to gas vapors in the bilge, I never want to see another and particularly don't want to be onboard when it happens.
What he said.
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Old 09-08-2016, 08:11 AM   #48
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If I thought it was 1 in 1000, or even 1 in 1,000,000......

But I doubt it's even that.

Look at the number of boats, explosions......and more so WHY gas fumes were in the boat.... and WHAT was the source of ignition.........and WHAT WAS OR WASN'T done to prevent the source of ignition from getting to the fumes.

Active risk management might drive that number to such a small ratio you might be 10 time more likely to die from 50 other causes.

Sure the numbers are hard to put a finger on...going either way....

So I don't have a problem with people being fearful of gasoline on a boat...a little fear is good to keep one honest.

I just think it should be talked about in realistic terms...not abstract statistics that create fear or regulation when some of those numbers are based on things that investigators would be hard to even recreate.

Risk? Manage it or get rid of it....not a big deal unless you dont.
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Old 09-08-2016, 09:45 AM   #49
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....... Do you use any sort of lift to help you get the dinghy to and from the water?........ .
Nope, just pull it over the bow rail and wrestle it into place. Takes two people. Probably could have done it by myself twenty years ago.

When I bought the boat, it had some sort of crane device with a block and tackle that the POs used to lift their outboard to the flybridge. It was a 5HP, probably 60 LB. I removed it.

I could probably reinstall it on the bow to lift the dinghy but for now, we manage without it.
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Old 09-08-2016, 09:50 AM   #50
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In theory, the new, EPA approved, impossible to pour without spilling, gas jugs are designed to not emit gasoline vapors. They have no vents either.
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Old 09-08-2016, 10:44 AM   #51
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In theory, the new, EPA approved, impossible to pour without spilling, gas jugs are designed to not emit gasoline vapors. They have no vents either.
Agree, although I have left mine out in the sun(not purposely)after filling my lawnmower, and the expansion due to sun exposure of the container is incredible. Not enough in my case to burst the container, but the previous post about covering with a white color seems to be a good idea
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Old 09-08-2016, 10:45 AM   #52
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In theory, the new, EPA approved, impossible to pour without spilling, gas jugs are designed to not emit gasoline vapors. They have no vents either.
Yes, In theory the new EPA compliant cans do not emit vapors, but in my experience, without a traditional vent the tank swells up in the sun until the pressure overcomes the weakest point. In my recent experience, it will scape where the hose fitting attaches to the tank. My new brand new Attwood 3 gallon tank was left standing on it's end in the back of a pickup and gas was escaping from that joint within a few hours. I know I should have left it flat, and preferably shaded but the point is that if the pressure built up enough to push liquid through that joint, it would have allowed vapor to escape just as easily if it were flat. Since most of the tanks have a similar fitting, I would expect most of the new EPA compliant tanks to have the same issue and I don't plan to return it but I will keep it on the swim platform or in the dinghy.

The green circle (ellipse really) shows where it was leaking.
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Old 09-08-2016, 10:53 AM   #53
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We are only supposed to fill it to a line. One gallon in a one gallon tank. That leaves an expansion space that should take care of heating. I suspect many folks (I often do) fill it as full as we can and that leaves no expansion space.
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Old 09-08-2016, 11:04 AM   #54
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We are only supposed to fill it to a line. One gallon in a one gallon tank. That leaves an expansion space that should take care of heating. I suspect many folks (I often do) fill it as full as we can and that leaves no expansion space.
Absolutely, when I go to the gas station to fill up my lawn equipment gas container, I never (bad me) consider expansion, its just trying to squeeze in as much as I can, so I don't have to go back as often (pia).But in defense, as soon as I get home, I will fill the lawnmower right away. The expansion issues, at least in my case, was always with a partially filled container(regardless of liquid level),just that is in the sun too long.
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Old 09-08-2016, 12:20 PM   #55
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We are only supposed to fill it to a line. One gallon in a one gallon tank. That leaves an expansion space that should take care of heating. I suspect many folks (I often do) fill it as full as we can and that leaves no expansion space.
In my case, the gas was not overfilled, it was above the fill line because the tank wasn't level. My point is, the EPA cap is supposed to prevent vapors from escaping, but if that joint is susceptible to liquid leaking through it, it will certainly allow vapor to pass through when pressurized to the same degree, thus making the vapor proof cap useless. You would actually experience greater expansion with a nearly empty tank than one filled to the max fill line, as the vapor will expand at a greater rate than the fluid.
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Old 09-08-2016, 12:22 PM   #56
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If I thought it was 1 in 1000, or even 1 in 1,000,000......

But I doubt it's even that.

Look at the number of boats, explosions......and more so WHY gas fumes were in the boat.... and WHAT was the source of ignition.........and WHAT WAS OR WASN'T done to prevent the source of ignition from getting to the fumes.

Active risk management might drive that number to such a small ratio you might be 10 time more likely to die from 50 other causes.

Sure the numbers are hard to put a finger on...going either way....

So I don't have a problem with people being fearful of gasoline on a boat...a little fear is good to keep one honest.

I just think it should be talked about in realistic terms...not abstract statistics that create fear or regulation when some of those numbers are based on things that investigators would be hard to even recreate.

Risk? Manage it or get rid of it....not a big deal unless you dont.
^^This.

Put the gas can where a spill will not happen, or if it does, it does not go below deck. Keep an eye on it. Wipe up any spills.

I carry a six gal squat shaped jug with a cork in the nozzle. This lets vapor escape if the sun shines on it. I only put a max of four gal in it. Sits on cockpit deck near the scupper. If it leaked, it would go out the scupper. Never had a problem. When I need to put gas in the dink motor, I pour about half gal into a one gal jug, and carry that to the dink and it stays there.

If I'm not traveling with the dink, then no gas on boat.

Just use common sense and understand the risks.
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Old 09-08-2016, 12:28 PM   #57
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Some people quote how there is a risk of explosion...

Others post be careful to avoid spills, unknown vapor escape, and mitigate risks so it ISN'T dangerous to transport gas......

And yet others posts how they do it incorrectly, and have gas spills and vapor escapes.....

Hmmmmmmm........wonder where statistics come from......
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Old 09-08-2016, 01:04 PM   #58
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Some people quote how there is a risk of explosion...

Others post be careful to avoid spills, unknown vapor escape, and mitigate risks so it ISN'T dangerous to transport gas......

And yet others posts how they do it incorrectly, and have gas spills and vapor escapes.....

Hmmmmmmm........wonder where statistics come from......
I'm pretty sure you are referring to me. I agree that gas can be transported safely though common sense and mitigation. I was simply sharing an anecdote of the failure of these EPA caps to accomplish the intended purpose. Yes it was careless and I am telling on myself, it was of no consequence because it was just in the bed of a pickup truck and corrected before any substantial spill occurred. My point is that if gasoline can escape, so can vapor and therefore the EPA cap is pointless.
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Old 09-08-2016, 01:20 PM   #59
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Yes, In theory the new EPA compliant cans do not emit vapors, but in my experience, without a traditional vent the tank swells up in the sun until the pressure overcomes the weakest point. In my recent experience, it will scape where the hose fitting attaches to the tank. My new brand new Attwood 3 gallon tank was left standing on it's end in the back of a pickup and gas was escaping from that joint within a few hours. I know I should have left it flat, and preferably shaded but the point is that if the pressure built up enough to push liquid through that joint, it would have allowed vapor to escape just as easily if it were flat. Since most of the tanks have a similar fitting, I would expect most of the new EPA compliant tanks to have the same issue and I don't plan to return it but I will keep it on the swim platform or in the dinghy.

The green circle (ellipse really) shows where it was leaking.

Thanks for the heads up on those tanks. Do you think that it would possibly be that manufacturer(cheaply made), or design issue?
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Old 09-08-2016, 02:34 PM   #60
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Is anyone aware of fumes getting into the bilge from a gasoline container stored outside the boat?

Every year I hear of propane explosions, or gas engine explosions. But I have yet to hear of gasoline fumes from an outside stored container being an issue.

My dock box in which I store gasoline is vented so that the fumes would go overboard.
Not an expensive adaptation of a dock box as it only required buying a few dollar grill and cutting a hole in the side.
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