Compressed Natural Gas

May 24, 2023
1
Hunter Legend 35.5 Toronto
Hi all,

I purchased my Hunter Legend 35.5 last year and it came with a Seaward stove/oven that used Compressed Natural Gas. There is a cylinder located under the Starboard Settee. I live in Ontario, Canada and cannot find anywhere that fill these cylinders or to purchase a new/extra bottle.

Would anyone be able to share a source where I can get mine refilled?

I have considered converting the stove/oven to propane and going that route. What are your thoughts?

Thanks!
 
Jan 7, 2011
5,463
Oday 322 East Chicago, IN
This site lists various filling stations in Canada…

Assuming you are in the Toronto area, there is a place listed near Mississauga.

IMG_3090.jpeg


As far as converting to propane, I think that CNG is a bit less readily available, but is also much safer than propane.

I am not sure what appliances you have, but you would want to make sure that a conversion kit is available first. Then, you will need to review the best practices for propane to ensure you do it right…this includes a tank locker that drains overboard, a solenoid to turn on the gas out in the locker when you want to use it, the proper flexible hose to connect the tank to the appliances, etc.

My boat has propane stove and oven. While I love the convenience, I am careful when using propane on the boat.

Greg
 
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Oct 26, 2010
2,110
Hunter 40.5 Beaufort, SC
I think you will find getting someone to refill it may be difficult. For someone else to refill it legally, it needs to be pressure tested (hydro'd) within a certain periodicity and marked on the tank. The best bet is to find a place that does "CNG tank exchange, but those are few and far between" if they even exist at all in your area. There are other threads from long ago you might check out. You can make your own adapter but you still have to find a CGN filling station and they are typically at a much higher pressure than your tank will allow and will probably say "no way". I have found one that will allow me to refill my tanks, but they don't monitor the tank area visually and if they saw me would probably come running out and stop me immediately.
 
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Oct 26, 2010
2,110
Hunter 40.5 Beaufort, SC
I see from @Tally Ho post that you may have cng stations around. Now figuring out who will let you use their station (normally at 3000psig or higher supply pressure) to fill a 2000 psig tank is the next step. I too have cng and prefer it but if I ever lose access to filling my tanks (which might happen anytime) I will probably have to convert to propane.
 
Oct 26, 2010
2,110
Hunter 40.5 Beaufort, SC
PS. If you do decide to convert, I might buy your empty tank if the date stamp on the tank is current and the tank is in good shape.
 
Jan 11, 2014
12,745
Sabre 362 113 Fair Haven, NY
Here's a post about converting a Seaward stove to propane
Seaward Stove Conversion « Catalina 38 International Association
A lot has changed in the 13 years since that article was posted. Parts to convert the stove are no longer available. The stove will need to be replaced and a propane locker installed. CNG tanks were basically scuba tanks and propane tanks are not the same size and shape. The propane locker needs to be sealed and vented overboard, the CNG locker did not need venting over board.
 
Jun 11, 2004
1,734
Oday 31 Redondo Beach
A lot has changed in the 13 years since that article was posted. Parts to convert the stove are no longer available. The stove will need to be replaced and a propane locker installed. CNG tanks were basically scuba tanks and propane tanks are not the same size and shape. The propane locker needs to be sealed and vented overboard, the CNG locker did not need venting over board.
All true.

That is why I have been using this device to refill my CNG tanks for the last several years.


I do this where CNG powered trucks, busses and cars fill up. Around here they are all self serve.

You have to decide for yourself if you think it is safe or not. Or whether it is legal or not.

I do recommend that at a minimum you have your tanks hydro pressure tested before filling. That is generally required every five years.

It generally costs about $2.00 at the CNG station to fill each tank to 2,000 pounds.
 
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Dec 25, 2000
5,909
Hunter Passage 42 Shelter Bay, WA
What type of shop/company were you able to find to hydro your tanks? Thanks in advance
Most major cities have businesses that can hydro test your tank. Seattle has one that charges $60 and takes a few days to complete and good for five years. Our older steel CNG tanks in good condition can be re-certed many times. They look for pitted or severe corrosion to determine whether it will pass re-cert.
 
Jun 11, 2004
1,734
Oday 31 Redondo Beach
Try a dive shop, if they can't do it, then they will know who can.
I used to use an industrial gas supplier who did it for $25. They went out of business so I recently went to a dive shop who did it for $35.

When looking at dive shops remember that many of them will send the tanks out to be tested. The ones who do it themselves will generally be less expensive. Make sure you explain on the phone what you have. Some will be reluctant to do it because it is not air and don't want to deal with a tank that has flammable gas in it. If so tell them you will make sure the tank is empty before bringing it in. And some might say they don't have the correct fitting for the tank. If it is like mine are (3AA2250) the threads are a tapered style while most of the more recent are straight.
 
Sep 14, 2014
1,278
Catalina 22 Pensacola, Florida
Just remember propane is heavier than air and sinks to lowest level in boat, CNG is lighter and will rise. Probably reason that cng was originally used in marine stoves down in cabins.
 
Oct 26, 2010
2,110
Hunter 40.5 Beaufort, SC
A propane shop would be more applicable.
I don't think so. Propane tanks are at a much lower pressure than a CNG tank. I don't think a propane shop would touch it with a 10 foot pole. CNG tanks are at a pressure of 2000+ psig.
 
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Oct 26, 2010
2,110
Hunter 40.5 Beaufort, SC
Just remember propane is heavier than air and sinks to lowest level in boat, CNG is lighter and will rise. Probably reason that cng was originally used in marine stoves down in cabins.
That is why I like CNG as long as I can keep finding sources for filling. By the way, if anybody out there has a good (no corrosion) CNG tank I'd be interesting in buying it. If it's got a current hydro all the better.
 
Dec 28, 2015
1,897
Laser, Hunter H30 Cherubini Tacoma
I don't think so. Propane tanks are at a much lower pressure than a CNG tank. I don't think a propane shop would touch it with a 10 foot pole. CNG tanks are at a pressure of 2000+ psig.
Agree but being in the field, they would have a better capability for referral. I find it hard to believe a dive shop would actually hydro a compressed gas cylinder due to knowledge and liabilities. I would assume they are sent out if you get that far.
 
Oct 26, 2010
2,110
Hunter 40.5 Beaufort, SC
Steel Dive tanks are the design as CNG tanks and dive tanks may even be at up to 3000 psig or more.. A dive shop may, however, hesitate to hydro a cng cylinder. Best bet may be an industrial gas supplier. CNG is almost all methane gas with an odorant added to be able to detect leaks. Brings up the idea that you could buy a tank of methane. Any gas experts (not that kind) that can offer some perspective.
 
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Dec 28, 2015
1,897
Laser, Hunter H30 Cherubini Tacoma
Steel Dive tanks are the design as CNG tanks and dive tanks may even be at up to 3000 psig or more.. A dive shop may, however, hesitate to hydro a cng cylinder. Best bet may be an industrial gas supplier. CNG is almost all methane gas with an odorant added to be able to detect leaks. Brings up the idea that you could buy a tank of methane. Any gas experts (not that kind) that can offer some perspective.
being pretty versed in flammable gases as a hazmat tech for 25 years, I would think a dive shop (I'm a cert diver) would be restricted by insurance to hydro a cylinder with pressurized flammable gas. They are not versed, trained or experienced to do so being it needs to be evacuated and inspected inside. I'll ask my shop next time I'm in there. I have yet to see a propane tank or CNG tank in the dive shop for hydro and knowing how dive shops struggle, if they could make some extra money and could faciliate hydro testing all cylinders, the shop would be covered with them along with all the scuba tanks.. This is why I believe a propane shop would be better suited for it. Not that they would perform the test but they would be much more familiar with the what's and who's. I would be very much interested in references you would have regarding your statmeent on scuba tanks are designed as CNG tanks specifically. I get the same pressure concept, my high pressure steal scuba tanks are rated at 3500psi but I believe DOT regulations restrict the filling of them with CNG, not just due to improper labeling,
 
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