I am buying a 1984 Orion 27 with a CNG installation that the surveyor says does not meet current federal regulations. This is the original installation. My concern is being able to insure the boat without retrofitting an airtight locker with vent as the regs suggest. Has any one had a similar situation and what was your solution? Thanks. --Gary
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lighter than air...
As CNG is lighter than air, the airtightness should be designed, in fact, to allow escaping gas to escape upwards, quickly! However, outside the US we use LPG (100% propane in most cases I believe, with butane used in some places) which is heavier than air, so is more dangerous - however, as it is stored at a lower pressure, the balance between the two is not easy to decide upon. LPG has higher energy than CNG, tho. The greatest risks seem to me to come from poor connections - so minimising these is the most important thing to focus on. However, the gas locker is a real potential source of a leak as the gas there is at its highest pressure and that's where the fuel is concentrated. So, if its a heavy gas, make sure it cannot leak below from the gas locker and if its a light gas, make sure it will dissipate upwards rapidly if there is a leak (whether the leak is in the gas locker or inside the boat). What is clear is that the standard European gas locker is wrong for CNG - you must put in a top vent, somehow (best make that a big sucker, too!). Above all, don't cheat on sealing and venting - you might not be around to hear your insurance claim refused, but family memebers will be. best wishes, Keith Williams
As CNG is lighter than air, the airtightness should be designed, in fact, to allow escaping gas to escape upwards, quickly! However, outside the US we use LPG (100% propane in most cases I believe, with butane used in some places) which is heavier than air, so is more dangerous - however, as it is stored at a lower pressure, the balance between the two is not easy to decide upon. LPG has higher energy than CNG, tho. The greatest risks seem to me to come from poor connections - so minimising these is the most important thing to focus on. However, the gas locker is a real potential source of a leak as the gas there is at its highest pressure and that's where the fuel is concentrated. So, if its a heavy gas, make sure it cannot leak below from the gas locker and if its a light gas, make sure it will dissipate upwards rapidly if there is a leak (whether the leak is in the gas locker or inside the boat). What is clear is that the standard European gas locker is wrong for CNG - you must put in a top vent, somehow (best make that a big sucker, too!). Above all, don't cheat on sealing and venting - you might not be around to hear your insurance claim refused, but family memebers will be. best wishes, Keith Williams
I have CNG
Gary, I have a 1982 Orion and have a CNG stove and the CNG bottle is in the locker inside of the cockpit. I only turn the bottle on whenever we want to use the stove. I was glad to have the CNG because I think it is much safer. As Keith Williams said it is lighter than air and will readily dissipate rather than collecting at a lower lever of the boat. It was my understanding that CNG did not have to adhere to the same ventalation requirements for LPG or other heavier than air gases. It was not an issue when I had my boat surveyed 4 years ago and when I had the boat insured, one of the questions pertained to the type of gas used for the stove but there were no detailed questions or inspections on the installation and ventilation. I am not sure where you could find the wirtten code requirements for CNG. I did a quick Google search but did not find anything definitive. Here is a link to an article about converting from LPG to CNG that gave some information. Maybe the Coast Guard could direct you to a good source. Later today I may have some time to search some more but in the meantime if you fine something I would be interested in comparing it to my current installation. Meanwhile enjoy your Orion. I have not regretted mine and the whole family has had great fun sailing the boat.
Gary, I have a 1982 Orion and have a CNG stove and the CNG bottle is in the locker inside of the cockpit. I only turn the bottle on whenever we want to use the stove. I was glad to have the CNG because I think it is much safer. As Keith Williams said it is lighter than air and will readily dissipate rather than collecting at a lower lever of the boat. It was my understanding that CNG did not have to adhere to the same ventalation requirements for LPG or other heavier than air gases. It was not an issue when I had my boat surveyed 4 years ago and when I had the boat insured, one of the questions pertained to the type of gas used for the stove but there were no detailed questions or inspections on the installation and ventilation. I am not sure where you could find the wirtten code requirements for CNG. I did a quick Google search but did not find anything definitive. Here is a link to an article about converting from LPG to CNG that gave some information. Maybe the Coast Guard could direct you to a good source. Later today I may have some time to search some more but in the meantime if you fine something I would be interested in comparing it to my current installation. Meanwhile enjoy your Orion. I have not regretted mine and the whole family has had great fun sailing the boat.
If it is actually CNG,
the surveyer is wrong and you should replace the surveyer. If it is propane, that is another matter. A CNG tank looks something like a scuba divers compressed air tank. You can put them just about anywhere inside the boat (probably not the battery box or engine compartment). A propane tank probably looks like something you might use on a barbeque and will have that kind of fitting. There are a variety of shapes of these but another tipoff would be a fill vent fitting. I think that is what it is called. Take another look to be sure but you should be ok with the factory setup as delivered.
the surveyer is wrong and you should replace the surveyer. If it is propane, that is another matter. A CNG tank looks something like a scuba divers compressed air tank. You can put them just about anywhere inside the boat (probably not the battery box or engine compartment). A propane tank probably looks like something you might use on a barbeque and will have that kind of fitting. There are a variety of shapes of these but another tipoff would be a fill vent fitting. I think that is what it is called. Take another look to be sure but you should be ok with the factory setup as delivered.
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