Kenyon 2 Burner Alcohol Stove, Replace? CD27

[Bruce Lumsden]

Warren-

I have the original Kenyon 2-burner pressurized alcohol stove that was original equipment with my 1975 CD 25. Though it works fine and doesn't leak, I would be happy to give it away for free to you or anyone else willing to cover the shipping. Personally, I think this type of stove is an accident waiting to happen....

I agree that alcohol is an expensive fuel and that it lacks the heat output of refined petroleum, however this stove certainly does put out sufficient heat to cook quickly, perhaps too quickly. Most of the time, I use my propane Magma grill to cook on deck and use the non-pressurized Origo alcohol burner below for those odd times when cooking on deck is uncomfortable due to rain, etc. I prepare for rough weather meals ahead of time by cooking while still in harbor and putting the hot stuff in thermos bottles. Works for me...

Regards,
Bruce Lumsden

Sine Qua Non (1980 CD27) has a little two burner alcohol stove. Looks like a drop-in type. Its old and it leaks alot so that fire hazard is a real concern. Consequently, I don't use it. I'd like to next year but I don't think its worth repairing in the state that its in. I'd rather just replace it. I don't have the model number with me (genius that I am). Does anyone familiar with this stove know if it is still made? Has anyone replaced one with a different unit? Anyone know if Kenyon is still in business? Any advice will be appreciated.

Thanks,
Warren Kaplan
Sine Qua Non
CD27
Oyster Bay Harbor, NY

JLumsden@gwi.net

[John R.]

The CNG regulator needs to be vented overboard, preferably as far aft as possible. You don't want any gas vapors of any type collecting inside any boat hull whether the gas is lighter than air or not. CNG being lighter than air still needs a way to escape the confines of a hull and cabin via ventilation of one method or another. Because CNG is under such high pressure that is the reason the regulator needs to be vented overboard. CNG systems are designed to have the regulators vented overboard and as far as I know that is what current ABYC standards call for. You don't want any gas of any kind leaking or venting inside a hull, no matter if it is lighter than air or not. A prudent installer will also incorporate a sniffer and alarm unit as a leak fail safe shutdown and audio visual warning indicator. An electric shut off solenoid will be employed in that type of system. However, the use of a shut off solenoid on CNG needs to be placed after the outlet port of the regulator due to the high pressures involved. In a propane installation the solenoid would be installed before the regulator.

By all means vent the regulator to the exterior of the hull and preferably at the transom. Be prudent and install an on/off control alarm sytem as well, such as a Xintex. Better safe than sorry.

Is the CNG compartment vented through the hull?

Mario

Warren,

The very first thing I replaced when Rhiannon was commissioned in 1984 was the Kenyon stove. I gave the thing away to one of the waterway gypsies and considered it good riddance -- alcohol in any form is lousy for cooking, IMHO. (Alcohol is for drinking but that marine stuff makes your fingernails hurt! Coleman fuel is not much better and makes terrible Dark & Stormies!)

Replaced the Kenyon with a Force Ten CNG flush mounted unit. The CNG tank is under the port settee berth (heavy things get put low and close to the centerline in Rhiannon). A 1/4" trim ring was necessary to get the Force Ten stove to mount properly but that will not be necessary when I put Corian on the countertops (see another post).

The main reasons I went with CNG: my daughter and friends could use the boat without fear (mine - they have no fear as teenagers) of blowing the boat up with LPG, cheap: (Public Service Gas fills the tank for $15 and it lasts all season, much better heat than alcohol (though admittedly not as good as LPG), and ease of containing a lighter-than-air gas in a normal storage compartment.

This stove has seen a lot of use. It works perfectly and is a snap to clean completely. Heeled over under sail I use a Forespar Mini-Galley mounted over the sink. Under power in reasonably flat water, the Force Ten works great. It has fiddles and tolerates some heeling and we actually use it like that sometimes. The Mini Galley is gimballed so heeling is not a problem.

Here's a great cookbook for sailors and a bit of a different philosophy for meal planning: "The Two Burner Gourmet: The Cookbook for the Cruising Yachtsman" by Terry Searfoss. Don't know if this is available anymore but it's worth the price.

One of the greatest pleasures of cruising is preparing really nice meals. The hassle (and odor) free stove helps make this possible.

For what it's worth,

Andy Denmark
CD-27 #270 "Rhiannon"
Oriental, NC (90 degrees, 10-12 SW wind and no clouds today)

[Andy Denmark]

John,

Of course, I gave these matters serious thought before doing this installation on my own boat. You addressed some of the factors I considered 18 years ago when doing this installation.

The CNG regulator needs to be vented overboard, preferably as far aft as possible.

On Rhiannon the regulator is vented overboard via the old holding tank vent hose that exits through the transom.

You don't want any gas vapors of any type collecting inside any boat hull whether the gas is lighter than air or not. CNG being lighter than air still needs a way to escape the confines of a hull and cabin via ventilation of one method or another.

Whatever gas vapors get into the cabin (usually not the kind one can put into a tank) dissipate quickly through the two dorades on the cabin top and the cowl vents in the engine compartment. Also, Cape Dories are noted for their almost total lack of airtightness. The fits around the companionway sliding hatch and hatch boards, to wit. I cannot find a place where gas can pool in sufficient concentration to be combustible. Broyle's (or is it Boyles?) Law is operative here.

A prudent installer will also incorporate a sniffer and alarm unit as a leak fail safe shutdown and audio visual warning indicator. An electric shut off solenoid will be employed in that type of system.

The human nose can detect an order of magnitude fewer ppb than any electronic sniffer -- this is a practical matter on a boat where ultimate simplicity (and safety) is the byword. If I were doing this for a customer there would be no question that solenoids, sniffer, warnings, etc. would be incorporated and ASBA specs followed to the letter. This is not a customer's boat, though.

However, the use of a shut off solenoid on CNG needs to be placed after the outlet port of the regulator due to the high pressures involved.

On every CNG installation I've seen the regulator is hard-plumbed to the tank connection, making it impossible to put the shutoff in the high-pressure line. Good point, though.

Thanks for the concern, John. There are practical limits to "rules and regulations" I think. Many of the regulatory specs, like so many of our laws, are written to protect a certain group of people from themselves. To me, sailing, and sailboats, is one of the few remaining things where we can appreciate the benefits of our own resposibilities and due diligence to boat and crew. It's an almost Darwinian thing - and to that group who needs the protection of an excess of laws and regulations because they can't take care of themselves, then there might often be a catastrophic price to pay without the excess regulation.

That said, before I ever sell Rhiannon (unlikely as my daughter wants her when I'm too old to sail), I'll put a sniffer, alarms, and cutoff valve on her. Meanwhile, I'll use mother nature's sniffer and adherence to a practical safety regimen to keep life (and the boat) as simple as possible.

Remember: an elephant is a mouse designed to MIL Specs.

As a matter of interest, when I ran Sailcraft Service we averaged a boat or so per year where the interior required major reconstructive work from fire damage due to alcohol-fueled stoves. A handful of alcohol fires resulted in total losses. In that same 12-year time frame there were probably two local boats that were destroyed by LPG explosions. There was never an accident involving accidental CNG combustion that I was aware of.

Andy

Warren,

The very first thing I replaced when Rhiannon was commissioned in 1984 was the Kenyon stove. I gave the thing away to one of the waterway gypsies and considered it good riddance -- alcohol in any form is lousy for cooking, IMHO. (Alcohol is for drinking but that marine stuff makes your fingernails hurt! Coleman fuel is not much better and makes terrible Dark & Stormies!)

Replaced the Kenyon with a Force Ten CNG flush mounted unit. The CNG tank is under the port settee berth (heavy things get put low and close to the centerline in Rhiannon). A 1/4" trim ring was necessary to get the Force Ten stove to mount properly but that will not be necessary when I put Corian on the countertops (see another post).

The main reasons I went with CNG: my daughter and friends could use the boat without fear (mine - they have no fear as teenagers) of blowing the boat up with LPG, cheap: (Public Service Gas fills the tank for $15 and it lasts all season, much better heat than alcohol (though admittedly not as good as LPG), and ease of containing a lighter-than-air gas in a normal storage compartment.

This stove has seen a lot of use. It works perfectly and is a snap to clean completely. Heeled over under sail I use a Forespar Mini-Galley mounted over the sink. Under power in reasonably flat water, the Force Ten works great. It has fiddles and tolerates some heeling and we actually use it like that sometimes. The Mini Galley is gimballed so heeling is not a problem.

Here's a great cookbook for sailors and a bit of a different philosophy for meal planning: "The Two Burner Gourmet: The Cookbook for the Cruising Yachtsman" by Terry Searfoss. Don't know if this is available anymore but it's worth the price.

One of the greatest pleasures of cruising is preparing really nice meals. The hassle (and odor) free stove helps make this possible.

For what it's worth,

Andy Denmark
CD-27 #270 "Rhiannon"
Oriental, NC (90 degrees, 10-12 SW wind and no clouds today)

trekker@coastalnet.com

[John R.]

Andy,

Great elephant metaphor!!!

You make some reasonable points assuming a savvy user of CNG and the use of a generally safe CNG gas system incorporated by most CNG users. I believe you will find that in any CNG system a on/off solenoid does indeed install after the regulator (at that point it is no longer very high pressure). Yes, a regulator on a CNG system is indeed hard plumbed to the tank, no hose is utilized until after the regulator due to the very high tank pressures (10,000 psi).

My comments were based on an average user situation, not an expert or highly experienced gas user such as yourself and not directed toward a total nitwit either.

The whole concept is to be safe at all costs when it comes to utilizing gas systems, no question about that. Assuming adequate ventilation and assuming no leaks are in existence by smell alone is very high risk in my opinion. It is best to have dedicated monitoring equipment to handle those possibilities. Let's face it, fires and explosions with stoves don't start by themselves, so much for average human prevention I think. You and I certainly agree that neither you nor I or any responsible individual or company would ever install a gas system without appropriate safety equipment installed for a owner as well and I think that is important criteria for all to heed that have any gas system on board such as CNG, propane, butane or are considering adding such a system.

About the safety prevention, what's your opinion on this simplistic scenario:

A owner has a couple people on board, they are out having a good time. They had the stove on at anchor to whip up a lunch or something. They turn the stove off after cooking. Everybody is preoccupied or distracted or are simply too lazy to open the CNG tank locker and turn the gas off at the main valve when finished using the appliance. While out in the cockpit sailing along a small trace of gas is leaking under high pressure behind the stove and galley furniture with a restricted area to open ventilation. Someone later comes below deck and turns on a switch or breaker or some other ignition source. Now what? Could result in a horrific situation. A sniffer can easily prevent this from occuring by shuting down the tank feed solenoid valve and initiating an alarm. That's an overly simplistic example but I think it illustrates the type of situation that can easily occur and the ability of appropriate gear to prevent such a potential disaster.

If the people are out in the cockpit how do you use the human nose as a sniffer in a situation like that before the risk presents itself? It's all about risk and *potential* danger. It seems to me the addition of a $200 sniffer/ alarm shutdown system is the wise thing to have on board when it comes to any gas system. I believe it's a small price to pay for the excellent insurance they afford.

You are so right about those pressurized alcohol stoves. I saw a few serious fire damage situations in our service days as well and I also am aware of a couple propane incidents that have occured in this area. I'm an advocate of CNG systems and also the Origo alcohol systems (which work great and are extremely easy for people to use and are safe).

Watch out for those MIL spec mice!

Thanks for your feed back Andy.

John,

Of course, I gave these matters serious thought before doing this installation on my own boat. You addressed some of the factors I considered 18 years ago when doing this installation.

The CNG regulator needs to be vented overboard, preferably as far aft as possible.

On Rhiannon the regulator is vented overboard via the old holding tank vent hose that exits through the transom.

You don't want any gas vapors of any type collecting inside any boat hull whether the gas is lighter than air or not. CNG being lighter than air still needs a way to escape the confines of a hull and cabin via ventilation of one method or another.

Whatever gas vapors get into the cabin (usually not the kind one can put into a tank) dissipate quickly through the two dorades on the cabin top and the cowl vents in the engine compartment. Also, Cape Dories are noted for their almost total lack of airtightness. The fits around the companionway sliding hatch and hatch boards, to wit. I cannot find a place where gas can pool in sufficient concentration to be combustible. Broyle's (or is it Boyles?) Law is operative here.

A prudent installer will also incorporate a sniffer and alarm unit as a leak fail safe shutdown and audio visual warning indicator. An electric shut off solenoid will be employed in that type of system.

The human nose can detect an order of magnitude fewer ppb than any electronic sniffer -- this is a practical matter on a boat where ultimate simplicity (and safety) is the byword. If I were doing this for a customer there would be no question that solenoids, sniffer, warnings, etc. would be incorporated and ASBA specs followed to the letter. This is not a customer's boat, though.

However, the use of a shut off solenoid on CNG needs to be placed after the outlet port of the regulator due to the high pressures involved.

On every CNG installation I've seen the regulator is hard-plumbed to the tank connection, making it impossible to put the shutoff in the high-pressure line. Good point, though.

Thanks for the concern, John. There are practical limits to "rules and regulations" I think. Many of the regulatory specs, like so many of our laws, are written to protect a certain group of people from themselves. To me, sailing, and sailboats, is one of the few remaining things where we can appreciate the benefits of our own resposibilities and due diligence to boat and crew. It's an almost Darwinian thing - and to that group who needs the protection of an excess of laws and regulations because they can't take care of themselves, then there might often be a catastrophic price to pay without the excess regulation.

That said, before I ever sell Rhiannon (unlikely as my daughter wants her when I'm too old to sail), I'll put a sniffer, alarms, and cutoff valve on her. Meanwhile, I'll use mother nature's sniffer and adherence to a practical safety regimen to keep life (and the boat) as simple as possible.

Remember: an elephant is a mouse designed to MIL Specs.

As a matter of interest, when I ran Sailcraft Service we averaged a boat or so per year where the interior required major reconstructive work from fire damage due to alcohol-fueled stoves. A handful of alcohol fires resulted in total losses. In that same 12-year time frame there were probably two local boats that were destroyed by LPG explosions. There was never an accident involving accidental CNG combustion that I was aware of.

Andy

[Ken Coit]

Good thread. Thanks for your thoughts and the reminder that I need to spend some more money to upgrade my monitor and solenoid control to get rid of the false alarms.

I am also going to check to see where that regulator vent hose goes.

Parfait's CNG tanks are filled to about 2,500 PSI; are there 10,000 PSI tanks or was that a typo?

Keep on sailing,

Ken

Andy,

Great elephant metaphor!!!

You make some reasonable points assuming a savvy user of CNG and the use of a generally safe CNG gas system incorporated by most CNG users. I believe you will find that in any CNG system a on/off solenoid does indeed install after the regulator (at that point it is no longer very high pressure). Yes, a regulator on a CNG system is indeed hard plumbed to the tank, no hose is utilized until after the regulator due to the very high tank pressures (10,000 psi).

My comments were based on an average user situation, not an expert or highly experienced gas user such as yourself and not directed toward a total nitwit either.

The whole concept is to be safe at all costs when it comes to utilizing gas systems, no question about that. Assuming adequate ventilation and assuming no leaks are in existence by smell alone is very high risk in my opinion. It is best to have dedicated monitoring equipment to handle those possibilities. Let's face it, fires and explosions with stoves don't start by themselves, so much for average human prevention I think. You and I certainly agree that neither you nor I or any responsible individual or company would ever install a gas system without appropriate safety equipment installed for a owner as well and I think that is important criteria for all to heed that have any gas system on board such as CNG, propane, butane or are considering adding such a system.

About the safety prevention, what's your opinion on this simplistic scenario:

A owner has a couple people on board, they are out having a good time. They had the stove on at anchor to whip up a lunch or something. They turn the stove off after cooking. Everybody is preoccupied or distracted or are simply too lazy to open the CNG tank locker and turn the gas off at the main valve when finished using the appliance. While out in the cockpit sailing along a small trace of gas is leaking under high pressure behind the stove and galley furniture with a restricted area to open ventilation. Someone later comes below deck and turns on a switch or breaker or some other ignition source. Now what? Could result in a horrific situation. A sniffer can easily prevent this from occuring by shuting down the tank feed solenoid valve and initiating an alarm. That's an overly simplistic example but I think it illustrates the type of situation that can easily occur and the ability of appropriate gear to prevent such a potential disaster.

If the people are out in the cockpit how do you use the human nose as a sniffer in a situation like that before the risk presents itself? It's all about risk and *potential* danger. It seems to me the addition of a $200 sniffer/ alarm shutdown system is the wise thing to have on board when it comes to any gas system. I believe it's a small price to pay for the excellent insurance they afford.

You are so right about those pressurized alcohol stoves. I saw a few serious fire damage situations in our service days as well and I also am aware of a couple propane incidents that have occured in this area. I'm an advocate of CNG systems and also the Origo alcohol systems (which work great and are extremely easy for people to use and are safe).

Watch out for those MIL spec mice!

Thanks for your feed back Andy.

John,

Of course, I gave these matters serious thought before doing this installation on my own boat. You addressed some of the factors I considered 18 years ago when doing this installation.

The CNG regulator needs to be vented overboard, preferably as far aft as possible.

On Rhiannon the regulator is vented overboard via the old holding tank vent hose that exits through the transom.

You don't want any gas vapors of any type collecting inside any boat hull whether the gas is lighter than air or not. CNG being lighter than air still needs a way to escape the confines of a hull and cabin via ventilation of one method or another.

Whatever gas vapors get into the cabin (usually not the kind one can put into a tank) dissipate quickly through the two dorades on the cabin top and the cowl vents in the engine compartment. Also, Cape Dories are noted for their almost total lack of airtightness. The fits around the companionway sliding hatch and hatch boards, to wit. I cannot find a place where gas can pool in sufficient concentration to be combustible. Broyle's (or is it Boyles?) Law is operative here.

A prudent installer will also incorporate a sniffer and alarm unit as a leak fail safe shutdown and audio visual warning indicator. An electric shut off solenoid will be employed in that type of system.

The human nose can detect an order of magnitude fewer ppb than any electronic sniffer -- this is a practical matter on a boat where ultimate simplicity (and safety) is the byword. If I were doing this for a customer there would be no question that solenoids, sniffer, warnings, etc. would be incorporated and ASBA specs followed to the letter. This is not a customer's boat, though.

However, the use of a shut off solenoid on CNG needs to be placed after the outlet port of the regulator due to the high pressures involved.

On every CNG installation I've seen the regulator is hard-plumbed to the tank connection, making it impossible to put the shutoff in the high-pressure line. Good point, though.

Thanks for the concern, John. There are practical limits to "rules and regulations" I think. Many of the regulatory specs, like so many of our laws, are written to protect a certain group of people from themselves. To me, sailing, and sailboats, is one of the few remaining things where we can appreciate the benefits of our own resposibilities and due diligence to boat and crew. It's an almost Darwinian thing - and to that group who needs the protection of an excess of laws and regulations because they can't take care of themselves, then there might often be a catastrophic price to pay without the excess regulation.

That said, before I ever sell Rhiannon (unlikely as my daughter wants her when I'm too old to sail), I'll put a sniffer, alarms, and cutoff valve on her. Meanwhile, I'll use mother nature's sniffer and adherence to a practical safety regimen to keep life (and the boat) as simple as possible.

Remember: an elephant is a mouse designed to MIL Specs.

As a matter of interest, when I ran Sailcraft Service we averaged a boat or so per year where the interior required major reconstructive work from fire damage due to alcohol-fueled stoves. A handful of alcohol fires resulted in total losses. In that same 12-year time frame there were probably two local boats that were destroyed by LPG explosions. There was never an accident involving accidental CNG combustion that I was aware of.

Andy

parfaitNOSPAM@nc.rr.com

[Larry DeMers]

Hi John,

Good Thread! Hey, was wondering about the 'sniffer' for CNG. Since CNG is lighter than air, won't you have that sniffer up near the ceiling? Since the gas disperses fairly quickly as it rises, that would seem (to me..an alcohol burner) to make detection a hit or miss proposition unless the detector was put in a place where the gas would accumulate before dispersing.
How did you folks handle that aspect of detection?

Cheers,

Larry DeMers

Andy,

Great elephant metaphor!!!

You make some reasonable points assuming a savvy user of CNG and the use of a generally safe CNG gas system incorporated by most CNG users. I believe you will find that in any CNG system a on/off solenoid does indeed install after the regulator (at that point it is no longer very high pressure). Yes, a regulator on a CNG system is indeed hard plumbed to the tank, no hose is utilized until after the regulator due to the very high tank pressures (10,000 psi).

My comments were based on an average user situation, not an expert or highly experienced gas user such as yourself and not directed toward a total nitwit either.

The whole concept is to be safe at all costs when it comes to utilizing gas systems, no question about that. Assuming adequate ventilation and assuming no leaks are in existence by smell alone is very high risk in my opinion. It is best to have dedicated monitoring equipment to handle those possibilities. Let's face it, fires and explosions with stoves don't start by themselves, so much for average human prevention I think. You and I certainly agree that neither you nor I or any responsible individual or company would ever install a gas system without appropriate safety equipment installed for a owner as well and I think that is important criteria for all to heed that have any gas system on board such as CNG, propane, butane or are considering adding such a system.

About the safety prevention, what's your opinion on this simplistic scenario:

A owner has a couple people on board, they are out having a good time. They had the stove on at anchor to whip up a lunch or something. They turn the stove off after cooking. Everybody is preoccupied or distracted or are simply too lazy to open the CNG tank locker and turn the gas off at the main valve when finished using the appliance. While out in the cockpit sailing along a small trace of gas is leaking under high pressure behind the stove and galley furniture with a restricted area to open ventilation. Someone later comes below deck and turns on a switch or breaker or some other ignition source. Now what? Could result in a horrific situation. A sniffer can easily prevent this from occuring by shuting down the tank feed solenoid valve and initiating an alarm. That's an overly simplistic example but I think it illustrates the type of situation that can easily occur and the ability of appropriate gear to prevent such a potential disaster.

If the people are out in the cockpit how do you use the human nose as a sniffer in a situation like that before the risk presents itself? It's all about risk and *potential* danger. It seems to me the addition of a $200 sniffer/ alarm shutdown system is the wise thing to have on board when it comes to any gas system. I believe it's a small price to pay for the excellent insurance they afford.

You are so right about those pressurized alcohol stoves. I saw a few serious fire damage situations in our service days as well and I also am aware of a couple propane incidents that have occured in this area. I'm an advocate of CNG systems and also the Origo alcohol systems (which work great and are extremely easy for people to use and are safe).

Watch out for those MIL spec mice!

Thanks for your feed back Andy.

John,

Of course, I gave these matters serious thought before doing this installation on my own boat. You addressed some of the factors I considered 18 years ago when doing this installation.

The CNG regulator needs to be vented overboard, preferably as far aft as possible.

On Rhiannon the regulator is vented overboard via the old holding tank vent hose that exits through the transom.

You don't want any gas vapors of any type collecting inside any boat hull whether the gas is lighter than air or not. CNG being lighter than air still needs a way to escape the confines of a hull and cabin via ventilation of one method or another.

Whatever gas vapors get into the cabin (usually not the kind one can put into a tank) dissipate quickly through the two dorades on the cabin top and the cowl vents in the engine compartment. Also, Cape Dories are noted for their almost total lack of airtightness. The fits around the companionway sliding hatch and hatch boards, to wit. I cannot find a place where gas can pool in sufficient concentration to be combustible. Broyle's (or is it Boyles?) Law is operative here.

A prudent installer will also incorporate a sniffer and alarm unit as a leak fail safe shutdown and audio visual warning indicator. An electric shut off solenoid will be employed in that type of system.

The human nose can detect an order of magnitude fewer ppb than any electronic sniffer -- this is a practical matter on a boat where ultimate simplicity (and safety) is the byword. If I were doing this for a customer there would be no question that solenoids, sniffer, warnings, etc. would be incorporated and ASBA specs followed to the letter. This is not a customer's boat, though.

However, the use of a shut off solenoid on CNG needs to be placed after the outlet port of the regulator due to the high pressures involved.

On every CNG installation I've seen the regulator is hard-plumbed to the tank connection, making it impossible to put the shutoff in the high-pressure line. Good point, though.

Thanks for the concern, John. There are practical limits to "rules and regulations" I think. Many of the regulatory specs, like so many of our laws, are written to protect a certain group of people from themselves. To me, sailing, and sailboats, is one of the few remaining things where we can appreciate the benefits of our own resposibilities and due diligence to boat and crew. It's an almost Darwinian thing - and to that group who needs the protection of an excess of laws and regulations because they can't take care of themselves, then there might often be a catastrophic price to pay without the excess regulation.

That said, before I ever sell Rhiannon (unlikely as my daughter wants her when I'm too old to sail), I'll put a sniffer, alarms, and cutoff valve on her. Meanwhile, I'll use mother nature's sniffer and adherence to a practical safety regimen to keep life (and the boat) as simple as possible.

Remember: an elephant is a mouse designed to MIL Specs.

As a matter of interest, when I ran Sailcraft Service we averaged a boat or so per year where the interior required major reconstructive work from fire damage due to alcohol-fueled stoves. A handful of alcohol fires resulted in total losses. In that same 12-year time frame there were probably two local boats that were destroyed by LPG explosions. There was never an accident involving accidental CNG combustion that I was aware of.

Andy

demers@sgi.com

[Ken Coit]

Larry,

Our sniffer is mounted above the athwartships counter on the dropped ceiling just aft of the stove and oven such that the corner cabinet door clears it. If I had two sniffers, I might put one in the locker as the lines, tanks, valves, and regulator are most vulnerable there. Or, I might save it as a spare if they don't age. Maybe they come sealed in a vacuum pack?

Keep on sailing,

Ken

Hi John,

Good Thread! Hey, was wondering about the 'sniffer' for CNG. Since CNG is lighter than air, won't you have that sniffer up near the ceiling? Since the gas disperses fairly quickly as it rises, that would seem (to me..an alcohol burner) to make detection a hit or miss proposition unless the detector was put in a place where the gas would accumulate before dispersing.
How did you folks handle that aspect of detection?

Cheers,

Larry DeMers

Andy,

Great elephant metaphor!!!

You make some reasonable points assuming a savvy user of CNG and the use of a generally safe CNG gas system incorporated by most CNG users. I believe you will find that in any CNG system a on/off solenoid does indeed install after the regulator (at that point it is no longer very high pressure). Yes, a regulator on a CNG system is indeed hard plumbed to the tank, no hose is utilized until after the regulator due to the very high tank pressures (10,000 psi).

My comments were based on an average user situation, not an expert or highly experienced gas user such as yourself and not directed toward a total nitwit either.

The whole concept is to be safe at all costs when it comes to utilizing gas systems, no question about that. Assuming adequate ventilation and assuming no leaks are in existence by smell alone is very high risk in my opinion. It is best to have dedicated monitoring equipment to handle those possibilities. Let's face it, fires and explosions with stoves don't start by themselves, so much for average human prevention I think. You and I certainly agree that neither you nor I or any responsible individual or company would ever install a gas system without appropriate safety equipment installed for a owner as well and I think that is important criteria for all to heed that have any gas system on board such as CNG, propane, butane or are considering adding such a system.

About the safety prevention, what's your opinion on this simplistic scenario:

A owner has a couple people on board, they are out having a good time. They had the stove on at anchor to whip up a lunch or something. They turn the stove off after cooking. Everybody is preoccupied or distracted or are simply too lazy to open the CNG tank locker and turn the gas off at the main valve when finished using the appliance. While out in the cockpit sailing along a small trace of gas is leaking under high pressure behind the stove and galley furniture with a restricted area to open ventilation. Someone later comes below deck and turns on a switch or breaker or some other ignition source. Now what? Could result in a horrific situation. A sniffer can easily prevent this from occuring by shuting down the tank feed solenoid valve and initiating an alarm. That's an overly simplistic example but I think it illustrates the type of situation that can easily occur and the ability of appropriate gear to prevent such a potential disaster.

If the people are out in the cockpit how do you use the human nose as a sniffer in a situation like that before the risk presents itself? It's all about risk and *potential* danger. It seems to me the addition of a $200 sniffer/ alarm shutdown system is the wise thing to have on board when it comes to any gas system. I believe it's a small price to pay for the excellent insurance they afford.

You are so right about those pressurized alcohol stoves. I saw a few serious fire damage situations in our service days as well and I also am aware of a couple propane incidents that have occured in this area. I'm an advocate of CNG systems and also the Origo alcohol systems (which work great and are extremely easy for people to use and are safe).

Watch out for those MIL spec mice!

Thanks for your feed back Andy.

John,

Of course, I gave these matters serious thought before doing this installation on my own boat. You addressed some of the factors I considered 18 years ago when doing this installation.
On Rhiannon the regulator is vented overboard via the old holding tank vent hose that exits through the transom.
Whatever gas vapors get into the cabin (usually not the kind one can put into a tank) dissipate quickly through the two dorades on the cabin top and the cowl vents in the engine compartment. Also, Cape Dories are noted for their almost total lack of airtightness. The fits around the companionway sliding hatch and hatch boards, to wit. I cannot find a place where gas can pool in sufficient concentration to be combustible. Broyle's (or is it Boyles?) Law is operative here.
The human nose can detect an order of magnitude fewer ppb than any electronic sniffer -- this is a practical matter on a boat where ultimate simplicity (and safety) is the byword. If I were doing this for a customer there would be no question that solenoids, sniffer, warnings, etc. would be incorporated and ASBA specs followed to the letter. This is not a customer's boat, though.
On every CNG installation I've seen the regulator is hard-plumbed to the tank connection, making it impossible to put the shutoff in the high-pressure line. Good point, though.

Thanks for the concern, John. There are practical limits to "rules and regulations" I think. Many of the regulatory specs, like so many of our laws, are written to protect a certain group of people from themselves. To me, sailing, and sailboats, is one of the few remaining things where we can appreciate the benefits of our own resposibilities and due diligence to boat and crew. It's an almost Darwinian thing - and to that group who needs the protection of an excess of laws and regulations because they can't take care of themselves, then there might often be a catastrophic price to pay without the excess regulation.

That said, before I ever sell Rhiannon (unlikely as my daughter wants her when I'm too old to sail), I'll put a sniffer, alarms, and cutoff valve on her. Meanwhile, I'll use mother nature's sniffer and adherence to a practical safety regimen to keep life (and the boat) as simple as possible.

Remember: an elephant is a mouse designed to MIL Specs.

As a matter of interest, when I ran Sailcraft Service we averaged a boat or so per year where the interior required major reconstructive work from fire damage due to alcohol-fueled stoves. A handful of alcohol fires resulted in total losses. In that same 12-year time frame there were probably two local boats that were destroyed by LPG explosions. There was never an accident involving accidental CNG combustion that I was aware of.

Andy

parfaitNOSPAM@nc.rr.com

[Richard Formica]

Warren,
I replaced my pressurized alcohol stove 2 years ago with an Origo 6000 (I think the stove top burners are the same as the 3000 it just has an oven underneathe). I did this because the business of heating up the burner prior to letting the vaporized alcohol in almost paralyze me with fear. Therefore I was willing to accept a "sterno" solution. I will not claim to cooking gourmet meals but I will say that when making pasta on the stove (ability to boil water and rebound after the pasta is in) and cooking a pork tenderloin I have no complaints. Honesty I see no difference between this and the pressurized alcohol stove. This made me wonder, since the fuel is the same, does pressurizing it change the heat output. I would say no. Am I wrong?

Richard Formica
Inerarity
CD36

Sine Qua Non (1980 CD27) has a little two burner alcohol stove. Looks like a drop-in type. Its old and it leaks alot so that fire hazard is a real concern. Consequently, I don't use it. I'd like to next year but I don't think its worth repairing in the state that its in. I'd rather just replace it. I don't have the model number with me (genius that I am). Does anyone familiar with this stove know if it is still made? Has anyone replaced one with a different unit? Anyone know if Kenyon is still in business? Any advice will be appreciated.

Thanks,
Warren Kaplan
Sine Qua Non
CD27
Oyster Bay Harbor, NY

[John R.]

Ideally sniffers are placed in near proximity to a point of potential leak source as you state Ken. Most alarm sniffer units are capable of connecting more than one sniffer. A complete sniffer location instruction outline is enclosed with every unit. The type of gas determines the ideal location position. You can easily seal extra sniffers in a vacuum bag like those used in a kitchen for food leftovers.

Larry,

Our sniffer is mounted above the athwartships counter on the dropped ceiling just aft of the stove and oven such that the corner cabinet door clears it. If I had two sniffers, I might put one in the locker as the lines, tanks, valves, and regulator are most vulnerable there. Or, I might save it as a spare if they don't age. Maybe they come sealed in a vacuum pack?

Keep on sailing,

Ken

Hi John,

Good Thread! Hey, was wondering about the 'sniffer' for CNG. Since CNG is lighter than air, won't you have that sniffer up near the ceiling? Since the gas disperses fairly quickly as it rises, that would seem (to me..an alcohol burner) to make detection a hit or miss proposition unless the detector was put in a place where the gas would accumulate before dispersing.
How did you folks handle that aspect of detection?

Cheers,

Larry DeMers

Andy,

Great elephant metaphor!!!

You make some reasonable points assuming a savvy user of CNG and the use of a generally safe CNG gas system incorporated by most CNG users. I believe you will find that in any CNG system a on/off solenoid does indeed install after the regulator (at that point it is no longer very high pressure). Yes, a regulator on a CNG system is indeed hard plumbed to the tank, no hose is utilized until after the regulator due to the very high tank pressures (10,000 psi).

My comments were based on an average user situation, not an expert or highly experienced gas user such as yourself and not directed toward a total nitwit either.

The whole concept is to be safe at all costs when it comes to utilizing gas systems, no question about that. Assuming adequate ventilation and assuming no leaks are in existence by smell alone is very high risk in my opinion. It is best to have dedicated monitoring equipment to handle those possibilities. Let's face it, fires and explosions with stoves don't start by themselves, so much for average human prevention I think. You and I certainly agree that neither you nor I or any responsible individual or company would ever install a gas system without appropriate safety equipment installed for a owner as well and I think that is important criteria for all to heed that have any gas system on board such as CNG, propane, butane or are considering adding such a system.

About the safety prevention, what's your opinion on this simplistic scenario:

A owner has a couple people on board, they are out having a good time. They had the stove on at anchor to whip up a lunch or something. They turn the stove off after cooking. Everybody is preoccupied or distracted or are simply too lazy to open the CNG tank locker and turn the gas off at the main valve when finished using the appliance. While out in the cockpit sailing along a small trace of gas is leaking under high pressure behind the stove and galley furniture with a restricted area to open ventilation. Someone later comes below deck and turns on a switch or breaker or some other ignition source. Now what? Could result in a horrific situation. A sniffer can easily prevent this from occuring by shuting down the tank feed solenoid valve and initiating an alarm. That's an overly simplistic example but I think it illustrates the type of situation that can easily occur and the ability of appropriate gear to prevent such a potential disaster.

If the people are out in the cockpit how do you use the human nose as a sniffer in a situation like that before the risk presents itself? It's all about risk and *potential* danger. It seems to me the addition of a $200 sniffer/ alarm shutdown system is the wise thing to have on board when it comes to any gas system. I believe it's a small price to pay for the excellent insurance they afford.

You are so right about those pressurized alcohol stoves. I saw a few serious fire damage situations in our service days as well and I also am aware of a couple propane incidents that have occured in this area. I'm an advocate of CNG systems and also the Origo alcohol systems (which work great and are extremely easy for people to use and are safe).

Watch out for those MIL spec mice!

Thanks for your feed back Andy.

[Neil Gordon]

West Marine and others will match a legitimate lower price. It's worth doing your homework but then seeing if your local store will give you the same discount but save you the drive and/or shipping.


Regards, Neil
s/v LIQUIDITY
Cape Dory 28 #167



neil@nrgordon.com