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CNG locker: necessary? if so, how to construct?

rwthomas1

Sustaining Partner
Hello All,
Well BoatUS sent me a nice letter today outlining all the things they had issue with from the survey on my "new" 1983 E38, that the surveyor "recommended" be fixed. They are all pretty easy and minor with one exception, the CNG bottle storage. The CNG bottle is in the lazzarette hatch on the starboard side attached to mounts mounted to the hull. Apparently this is not the way its done today as gaseous storage should be in a separate locker, away from the engine and vented to atmosphere.

I am not particularly concerned about CNG since it is lighter than air and will easily find its way out through the many little areas on a boat. If it was propane this would be more of an issue. The boat has two propane lockers at the stern and I suppose converting to propane is a possibility but it scares me a heck of a lot more than CNG.

Problem is BoatUS highlighted the statement the surveyor made. He did not actually recommend the CNG be fixed, he just noted that the storage method did not meet current standards. Current standards state that the bottle has to be stored separately from combustion engines. Since the bottle is in the lazarette hatch and there is a slide in hatch/cover to seal off the engine room from the lazarette area isn't the bottle then separate? To remedy the problem I could build a storage box out of plywood/fiberglass and had it vented to atmosphere but this will take up a lot of room. With a diesel engine I am not concerned about sparks either.

So what to do? Is BoatUS being overly picky? Is there a quick fix for this? Seems a little off the deep end to me....
Thanks, RT
 
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Chris Miller

Sustaining Member
Hi RT,
Ours is securely strapped in a cradle on a shelf in that locker. I understand the safety concern, but will say that it is not even on my list of things to worry about on the boat. As long as your CNG gear is all in good condition, properly secured, and correctly regulated, I personally wouldn't worry about it.
I will say that I always turn the bottle off when we are not using it, and disconnect the regulator from the bottle when we are leaving the boat for a while. I think that's just common sense with any system.
Just my $0.01 worth...
Chris
 

Lew Decker

Member III
The PO installed the CNG tank beneath the settee in the main salon only a few feet from the stove. I never once thought about problems with leaks until I returned to the boat after a week's absence and discovered the tank was empty. Hmmm. Wonder what would have happened if I had been sleeping aboard with all the hatches shut? Since the gas is lighter than air, it found its way out of the boat. When I slid the hatch open, I never smelled gas at any time. I didn't even know the tank was empty until I tried to make coffee. Now, I turn the tank on and off at the valve each time I use it. Anyway, I may move the tank to the lazarette just to be safe. I won't switch to propane, though. I can still get CNG and I'm not sailing off into the sunset anytime soon:oops: .
 

ted_reshetiloff

Contributing Partner
I have the exact same setup as Chris on his 38 with the bottle strapped to the shelf in the cockpit locker. There should be a line running from your regulator to a vent in the transom. This is in case excess pressure above the regulators capacity builds up it can be released to the outside. I would advise you check all of your CNG connections with soapy water, make sure the bottle is adequately secured, and make sure you turn off the bottle when not using the stove. Beyond that I personally dont think you need to be concerned. Am I a CNG expert? No but this is how I have my boat set up so if it blows up I will have some company in heaven :egrin:
 

u079721

Contributing Partner
Not a problem

ted_reshetiloff said:
I have the exact same setup as Chris on his 38 with the bottle strapped to the shelf in the cockpit locker. There should be a line running from your regulator to a vent in the transom. This is in case excess pressure above the regulators capacity builds up it can be released to the outside. I would advise you check all of your CNG connections with soapy water, make sure the bottle is adequately secured, and make sure you turn off the bottle when not using the stove. Beyond that I personally dont think you need to be concerned. Am I a CNG expert? No but this is how I have my boat set up so if it blows up I will have some company in heaven :egrin:


Ted, didn't the surveyor that did your 38 prior to purchase make the same recommendation to enclose your CNG bottle? I was just wondering because like everyone else I don't view this as a real concern, just a legal one to be sure that your insurance in not void.
 

rwthomas1

Sustaining Partner
My install is identical to Chris' and Teds. I guess the main question is what to tell BoatUS? Do I send back the reply form stating all the "issues" have been remedied and not worry about it? Do I call/write to them and challenge the surveyor on the grounds that:
a) the boat meets the requirements of the year it was built, updating is unpractical, expensive, etc.
b) The likelyhood of having a CNG issue is almost nill as it is lighter than air.
c) the lazzarette hatch is indeed separate from the engine and therefore should meet the requirments.
Let me know what you think. Thanks, RT
 

lbertran

Member III
Call Boat US

And discuss this with an underwriter. I have Boat US insurance and when I bought my boat in Dec. 2004, the surveyor said the CNG installation was fine. My installation is identical to Rob's and Ted's. Boat US did not require any modification at all. They only required that I attach a placard somewhere near the tank, with instructions on how to deal with a leak. Good luck.

Laura Bertran
Footloose, 1985 E35-3
 

jmoses

Member III
CNG Issues and ABYC

RT,

One of the major issues with CNG is an explosion from an electrical source and not so much a 'combustion engine'. As a result, having the CNG bottle in close proximity to electrical contacts is the major situation I look for (BUT, the bottle should not be in the actual engine compartment - duhh!). Also, is the bottle well secured? Are there vents to the exterior in close proximity to the bottle (high up to allow gas to escape)? Is the bottle handle free and does it turn? Is the guage working? Is the hose and regulator in decent shape? Is the regulator discharge hose vented to atmosphere? Etc.

After that, it's a judgement call on my part as CNG is not as dangerous as LPG (in my opinion). However, I would definately recommend getting ANY LPG or CNG bottle out of any living spaces as you may gas yourself or it may explode from an electrical spark (battery or AC/DC connection). Not to mention, the vent is not to the exterior I imagine.

What does ABYC have to say?

A-22.9.5.2 states that " The pressure regulation shall include a high flow restrictor located on the cylinder pressure side of the regulator which shall:

A-22.9.5.1 "actuate and control gas flow through the vent system to the open atmosphere in the event of regulator malfunction"

BREAK-------------------

A-22.9.6.1 "Relief vent outlet(s) shall not discharge to the interior of the vessel" (!!!!)

A-22.9.7 "Vent discharge system shall be located and designed to prevent water from entering the regulation system. The vent hole shall be protected against entry of foreign matter."

A-22.12.1 "CNG systems with connected capacity greater than 100 cubic feet SHALL provide for storage locker"

A-22.12.2 "CNG cylinders and regulators ... shall be located in a well ventilated area."

A-22.12.3 "CNG cylinders and regulators shall be readily accessable."

A-22.12.4 "CNG cylinders shall not be installed in compartments containing and internal combustion engine."

A-22.12.5 "CNG cylinder storage compartments shall not have openings which communicate with the engine space above the level of the regulator."

A-22.12.6 "CNG cylinders shall be located at LEAST one meter from an attended open flame...." (i.e. not near the stove or CNG appliance)

A-22.13.4 "Compartments or lockers in which CNG cylinders are stored shall have a ventilation opening above the cylinder."

Once a system is over 100 cubic feet, then the guidelines are different. I assume you don't have a 100 cubic feet system? Most tanks are the scuba tank size and are under 100 CF...but check your bottle.

Anyway, I don't know what the surveyor saw or was thinking, but as long as the regulator vent is to the outside, protected from water and foreign matter ingress, a vent is intalled above the regulator height, there are no open electrical contacts in the near vacinity, nor is the tank stored in a habitable space or with the engine, I don't see a problem with your install. I have CNG as well and it's fine in the cockpit locker with a vent over the bottle and the vent hose to the extereior. Plus I turn off the bottle when not in actual use....that's your best safety practice in my mind.

Regards,

J Moses
 
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chaco

Member III
Get the tank OUT OF YOUR LIVING SPACE and in to an AIRTIGHT
Locker in your Cockpit !
Nobody will convice me that having a 2000 PSIG CNG Tank under my
Galley Sattee is SAFE.
One of the first things recommended by my Surveyor was to GET RID
of the HIGH PRESSURE CNG BOMB in the Galley and go propane with a
Cockpit Locker-AIRTIGHT/VENTED/CONTROLLED up to date storage cabinet.
Sorry folks I have been working with GAS for 30+ years in HVAC and I
do not buy HIGH PRESSURE CNG Tanks as SAFE in an interior MARINE space.
 

jmoses

Member III
Rest assured....... CNG is safe

Dan,

I agree that having a CNG tank in an internal living space is not optimal, but CNG is no more likely to explode than LPG. A CNG (or LPG) tank properly intalled in a non-habitable space per ABYC guidleines is safe (in my opinion). If they were soo bad, they would be banned or un-insurable. In Fact, I don't recall the last time I heard about a boat blowing up due to CNG leak, but I'm sure someone will fill me in. In fact, I've heard of more Scuba tanks exploding than CNG tanks. However, I can recall the last local catastrophic explosion due to LPG.....it was last year in Sausalito - it destroyed the boat and damaged several others near-by.

Granted, CNG is not as common as LPG on boats, but in my opinion, as a surveyor, it would a disservice to tell a boat owner to remove their CNG tank if it is installed properly and working correctly. Yes, I'd tell a boat owner to remove the tank out of the living space (ABYC recommneds the same - see prior post on ABYC), but why make someone spend money on something that is 99.999% safe (when installed and used correctly) and perfectly acceptable to insurance underwriters, ABYC and boat builders? How many documented boat explosions do you know of related to CNG? I'd like to hear them as I don't know of any. What is your reasoning bhind CNG being unsafe? There are CNG pressure regulators are all over the place next to homes, on pipelines and at factories (granted, most of them are not multi-1,000's of PSI). Regardless, there are mega PSI CNG pipe lines all over the country and they usually explode when hit by a back-hoe or jack hammer (i.e. human error).

I have been on boats for 35 years (professionally and recreational) and surveying for quite a few of them and belive me, a well installed CNG tank is perfectly safe if the correct safety precautions are ustilised. The same is true for gasoline tanks (talk about a bomb!) as well as LPG tanks (another bomb!). In all circumstances, if the correct safety precautions are followed, common sense is used and wreckless abandon is not your modus-operendi, then rest assured, you are safe. If you ask me, I find more electrical hazards on boats than anything else (60% of my findings!). A distant second is thru-hulls/sea connections (25%). Other than inadequate LPG encosures and inoperable LPG solinoids, I don't recall much else with LPG or CNG tank issues. In fact, no operable fire extingusihers or no distres signals is more alarming to me than almost anything else on many inspections.

Lets' look at the numbers:
According to USCG 2004 property damage and accident stats from the period 1999-2004, your highest probability of death or damage is a collison with another vessel (30% of reported accidents in 2004). Collision with a fixed object is next (10.7%). Fire or explosion from fuel is down the list @ 3.3%. A fire or explosion from source other than fuel = 1.1% (I suspect the majority of these are electrical in nature - Boat US stats reveal that the majority of non-fuel boat fires are electrical in nature). In fact, you are more likely to sink at the dock (2.7%), be swamped at sea (5.2%), or run aground (4.4%) than explode or burn due to a non-fuel fire. Non-fuel fires caused 1 death in 2004 and remains consistant @1 to 4 people per year for the past 5 years.

If there is a safety message to disseminate then it's "WEAR YOUR LIFE JACKET!" as 30% of all deaths in 2004 were due to falling overboard and another 27% drowned due to capsizing, so clearly, wearing a life jacket would be more prudent advice, in my opinion, not removing CNG tanks. The lone death from an explosion other than fuel = 0.15% of the total 676 recreational boating deaths in 2004 (the cause of that death in a fire is unknown, and I doubt it was CNG). Past years are similar.

Anyway, I don't see any trend in the danger in CNG tanks and explosions that are alarming or remotely curious. If you don't beleive me have a look at the 50 pages of past boating accidents compiled by USCG :

http://www.uscgboating.org/statistics/Boating_Statistics_2004.pdf

John M.
 

chaco

Member III
The Old Tank location is now a storage locker.
CNG is not commonly available here in SoCal or Worldwide.
This helped me in my decision to switch to propane, while I changed the
Tank location to the Starboard Cockpit Locker.
I removed the Gas Range and will install a Force 10 2-burner propane stovetop in it's place.
To complete the project I plan on installing a 2-10lb vertical tank system
from Trident Marine (www.tridentmarine.com).
You will find a good installation diagram in "LPG Regiulators / Assembly
Option Diagrams". West Marine also has a good a good article on Marine
Gas Appliance Systems in their West Advisor.
I will install the Trident Gas Cylinder Locker in the vertical position
in the aft section of the Cockpit Locker, keeping in mind Cylinder removal
for refilling. In our EYO Specs and Docs you can download the E35-II
Manual. There are diagrams on a plywood/fiberglass gas cylinder locker
located the Starboard Cockpit Locker area, in the horizontal position.
On the High Pressure side of the Regulator I will use Rated Factory Hose
sections. On the Low Pressure (7-14" WC-Water Column=.25-.50 PSIG)
side you can buy bulk Rated Hose and do your own fittings with brass barb/
SAE Flare Swivel/NPT connectors (www.andersonfittings.com). I like the
Grip-On Barb/Flare/NPT fittings. I also use hose clamps with these
push-ons for added safety. The long hose runs in the bilge will be run in
nylon hose conduit to prevent ANY future chaffing. The exposed hose will
be supported throughout with SS c-clamps and nylon hose protectors.
Test ALL your fittings with a 50/50 solution of dishsoap/water and rinse it
off with water, as tests are good to prevent fitting and hose deterioration.

Good Luck on your tank relocation /) /)
 
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jkm

Member III
Dan

Up in MDR CNG is readily available.

Nonetheless I go down to Oceanside on occasion for a weekend in a condo next to the pier. An easy jog to your slip.

I will contact you before my next visit so I can visit your boat and check out your many improvements.

John
 

u079721

Contributing Partner
Anybody else fill their own tanks?

In my part of Michigan there was no local source for CNG tank refills, so we had to drive two hours or ship them off, at $40 to $50 a pop. I came across a web site for Corp Brothers (http://www.corpbrothers.com/marine.htm) that sold an adaptor that allowed you to refill your tank from a CNG filling station. I had never heard of these stations, but they are all across the country in locations where utilities and cities use CNG for fleet vehicles. (You can find one near you at: http://www.eere.energy.gov/afdc/infrastructure/refueling.html ) Anyway, there was one about an hour away, so my dock mate and I bought an adaptor for $140, which we figured would pay for itself the first time we filled our 4 tanks.

The filling station had two different pumps, 3000 psig and 3600 psig. I was told over the phone that it was safe to use the 3000 pump, but NOT to use the 3600 pump as that would over pressure the tank. (Which would be a VERY bad thing.) You screw the adaptor on the tank fitting, connect the quick release pump nozzle, and flip the lever. Then there is this big woosh sound, and in about 2 seconds the pump is full. Scared the hell out of me, I don't mind telling you.

When done the gauge on the pump read about 2700 psi, which is slightly more than the tank is rated for I guess, but not more than I found on some of the refills I had obtained in the past. (This pressure obviously depends greatly on the ambient temperature.) The really neat thing was the cost - just $0.46 a tank. So instead of $160 for 4 refills it only cost us $1.84.

The really scary thing about all this is transporting the tanks. The tanks I have always used at work (as a research chemist in the lab) had screw tops to protect the tanks while in transit. But these bottles don't. Is that because they are less than 3000 psi? Don't know, but I have to tell you that the though of what could happen during an accident as I was travelling down the highway in my van with four bottles full of CNG is enough to make you pay attention to the road. I also always wondered whether transporting the tanks myself was even legal?

My dock mate and I used that adaptor for about 8 years, at four refills a year, so we definitely got our money's worth. One complication is that since we were never turning in the bottles, getting the tanks pressure tested was now up to us, rather than to the exhchange location. This turned out to be fairly easy, as you could drop off the tank at any SCUBA or dive shop and get it pressure tested (reguired every five years) for just $25 each.

I was always super careful when doing this, but the lack of oversight kind of bothered me. I mean there was no one at the pump to check whether I knew what I was doing, or whether the tank I was filling had been certified in the last five years or not.

About five years ago I got a registered letter from the lawyers at Corp Brothers saying that many filling stations had now switched to 4500 psig pumps, and that a tank failure would result if the tank were filled from such a station. As such they strongly recomended that I immediately stop using the adaptor, and they would no longer sell them. Since our station still had 3000 psig pumps, we kept using it with no problems.

When I sold Rag Doll in 2004 I thought about including the adaptor (my dock mate no longer needed refills), but then I considered the liability of the situation and thew the adaptor away instead. There is a lot I miss about owning my Ericson, but filling those CNG tanks isn't one of them.
 

soup1438

Member II
CNG vs LPG...

I recall some stoves had an ability to run from either natural gas or LPG-- though the switch-over is NOT painless, considering that you had to use a different pressure regulator *and* every burner needed to have the jets changed, all because the air/fuel ratios need to be different for the two fuel types.

One boat I was looking at has a fairly new CNG stove which was in apparently excellent condition but the CNG bottle lived strapped to the bottom of the hanging locker. Now, having some experience (albeit not recently) with SCUBA gear, I got a bit itchy on seeing this cylinder. While I realize that "normal" or even under some fairly pathological conditions this tank wouldn't be much of a threat, my limited experience w/ sailing indicates that Murphy's Law is, for the most part, unusually optimistic.

All right, I admit it, my paranoia, like Spinal Taps' amplifiers, does spend a lot of time at 11, if not higher. So, whether this is reasonable or not, it does provide some prejudices.

So, my idiotic question is this: can any of the CNG stoves out there be converted from CNG to LPG by switching jets and regulators? Or can someone point to a good website providing information about stove/range design?

When I lived in PA way back when, one guy who does oil heat said "Modernize. Go gas. Go boom." I grew up with natural gas appliances so I am not entirely displeased by it, but I figured this question could be asked.

I also bring this up because my wife was exposed to volatile plastics (hydrocarbons) and gets a bit asthmatic around kerosine but hasn't had too many problems with natural gas, so that's *also* something of a factor (making an Atomic Four look like a good thing).

Having to rip out what's there and replace it completely rather than merely arranging for an LPG (or CNG) locker in the lazarette or the like would strike me as over-doing paranoia.
 

jkm

Member III
It's fairly simple to convert an appliance to LPG. You need to change the jets and a little Google work will find you sources. RV shops are a good source for jets, so are plumbing/HVAC shops.

Off course you'll have to revamp your regulator, bottle and etc.

I researched converting mine, but elected to stay with CNG as it is available.
If I cruise and run out I just cook with my Magma. I keep small propane bottles hanging in a bag off the rail. That stuff, LPG, scares me.

John
 

rwthomas1

Sustaining Partner
I have contacted BoatUS and the Surveyor. BoatUS had requested I contact the Surveyor and see what he recommended I do. His research indicates he was wrong to have indicated the CNG cylinder was stored incorrectly. Here is what he sent me:

Compressed Natural Gas [CNG] Storage Containers
NFPA 302: Fire Protection Standard for Pleasure and Commercial Motor Craft, 2004 Edition in Section 8.5 "LPG and CNG Systems for Permanently Installed Appliances":
NFPA 302-8.5.15.1 states:
LPG and CNG containers, regulating devices, and safety equipment shall meet the following criteria:
A- Rigidly Secured
B- Readily Accessible
C- Protected by a dedicated locker

NFPA 302-8.5.15.2.2 gives an exemption for the size of a CNG system that does not need to be in a dedicated locker. The size is 100 cubic feet while the gas is at 14.5 PSI and 70º F. The 2-3 thousand PSI tanks are exempted from the dedicated locker as long as their capacity is less then 100 cubic feet. Therefore the scuba tank size bottle which contains 72 cubic feet at 14.5 PSI and 70º F is exempt from the locker requirement.
NFPA 302-8.5.15.2.2 states:
A CNG container shall not be required to be installed in a dedicated locker in CNG systems with a single container connected to the system having a capacity to hold 100 cubic feet or lee of gas when the gas is at 14.5 PSI and 70º F.
>>>>>>>>>>>>>>>>>>>>>>>>>>
ABYC Standards and Recommended Practices for Small Craft, July 2005 edition in Section A-22 "Marine CNG Systems" states:
A-22.12.1 CNG systems with connected capacity greater than 100 cubic feet shall provide for storage lockers (see A-22.13.5.2)
A-22.13.5.2 Partially states:
Installed in a locker which shall be:
a. vapor tight to the hull interior,
b. vented to the open atmosphere outside the boat,
Therefore the scuba tank size bottle which contains 72 cubic feet at 14.5 PSI and 70º F is exempt from the locker requirement.

So with this information in hand I will be speaking to BoatUS and I expect the issue to be closed. I have no particular fear of a CNG system that is configured the way mine is and correctly maintained. LPG is far scarier to me since it is heavier than air and therefore far more likely to find its way to the bilge, collect and ignite there. CNG in a cockpit locker will just rise up into the atmosphere in the event of a small leak. Even a large leak occuring in a short period of time would need an ignition source to cause an explosion. A leak like this would likely vent off harmlessly from an unoccupied boat. CNG is readily available at the local marinas here in RI so refilling is not a problem. RT
 

ted_reshetiloff

Contributing Partner
Conversion to Propane I found very little resources available for the older Regal stoves installed in Ericsons. The company that made them went out of business and I have yet to find the correct info for converting the burner venturies. Not really something you want to make a mistake on... If someone has other info please share, but I ran that thread last fall I think. Short of replacing the stove I gave up on this as CNG is available in my area too and I find a tank lasts me all summer as I grill out more than anything. For extended cruising we will replace the stove and install the propane. My 89' E 38 has the locer just need the plumbing and saftey gear.
 

chaco

Member III
It's a GAS !
Natural Gas- 1000BTU/CF (Ave.) 0.63SG (Air 1.0 SG)
LPG - 2550 BTU/CF-92000BTU/GA 1.52SG

CNG ScubaTank - 72CF(?) X 1000BTU/CF = 72000 BTU
10lb/2.5GA LPG Tank - 2.5GA X 92000BTU/GA = 2300000 BTU

The LPG gas oriface will be smaller and is available for most (new) appliances.
The regulator will also need to be changed.
The regulated pressure is the same 7-11"WC or 0.25-0.50PSIG
 
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ted_reshetiloff

Contributing Partner
Yeah I was pretty sure I would need smaller orafices for the burners. Problem is finding a set that will fit in my NLA stove. I thought of brazing them shut then drilling with carburator bits once I knew the correct diameter but found other projects more important. If I went the LPG route it would be new tank, regualtor, solenoid, sniffer, hoses, and orifices or stove.
 
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