High or Low for CO?

[Kings Gambit]

I’ve not installed a CO monitor in either of the two cruising yachts we’ve owned. My surveyor of late has strongly recommended installing one or more now on the Bavaria. The Diesel engine exhaust system runs under the bunk of the port-side quarter berth overlain by a loose access board; the berth being enclosed (i.e., cabin). That’s where the water muffler resides. Plus, we have ducted heating from an Espar diesel-fired heater, the exhaust for which is high topsides at the starboard transom, a couple of feet above the Diesel engine exhaust. So, to alert early while sleeping in the quarter berth with the Espar running, where is a CO monitor best placed to detect incoming CO? High inside the cabin, low inside the cabin, or elsewhere outside the cabin? Also, assuming some diesel exhaust can escape the water muffler (which is rusting) and enter the cabin via the access while running on diesel power, same question. Opinions?

 

[Don S/V ILLusion]

Hot CO (heater) rises; warm CO (engine exhaust) rises.

 

[sail sfbay]

While diesel fuel combustion engines produce much lower concentrations of CO than gasoline engines, these emissions could certainly generate lethal ambient concentrations given a sufficient amount of time in an enclosed space and under suitable environmental conditions so your plan to install co alarms in the aft cabin is very sound!! Because carbon monoxide (CO) is slightly lighter than air and also because it may be found with warm, rising air, detectors should be placed on a wall about 5 feet above the floor.

 

[Richard19068]

, ...where is a CO monitor best placed to detect incoming CO?

Locating a Xintex Carbon Monoxide Alarm;
Because of the high risk of carbon monoxide injuries due to the nature of boats, it is recommend a carbon monoxide alarm be installed in the main cabin and in each sleeping area (ABYC A-24.7.2) of the enclosed accommodation compartment (ABYC A-24-4-5). If any two sleeping areas are partitioned, then one CO Alarm should be installed in each sleeping area. Larger craft often have aft and forward cabins with convertible sofas in the saloon. These boats will require three CO Alarm monitors. Installation should be at eye level height for convenient monitoring and service. Ordinary thermostat height is adequate. Ceiling installation is also allowed. DO NOT install a CO Alarm near a hatch or porthole through which water could be spilled on the device. DO NOT install in locations where temperature, moisture, and/or ultraviolet light affect the operation. DO NOT install in locations where the normal ambient temperature is below -30oC (-22oF) or exceeds 70oC (158oF). DO NOT mount within 1 foot (0.3 m) of corners, a door, or other ‘dead’ air spaces. DO NOT locate CO Alarm within 5 feet (1.5 m) of any cooking appliance or in direct airflow from air conditioning or heat vents. DO NOT locate CO Alarm in close vicinity of curtains, pillows, or other obstructions. Recommended Locations Stateroom Stateroom Galley Saloon Sleeper Couch Head Storage 12 Part Number 18149, E, 06/22/2017 Locating a Xintex Carbon Monoxide Alarm Continued NOTE: ABYC A-24.7.2: DETECTORS SHALL BE LOCATED TO MONITOR THE ATMOSPHERE IN THE MAIN CABIN AND EACH SLEEPING AREA. ABYC A-24.4.5: ENCLOSED ACCOMODATION COMPARTMENT - ONE CONTIGIOUS SPACE, SURROUNDED BY PERMANENT STRUCTURE THAT CONTAINS ALL OF THE FOLLOWING: - DESIGNATED SLEEPING ACCOMODATIONS - GALLEY AREA WITH SINK - HEAD COMPARTMENT

 

[Johnb]

When a chunk fell out of our mixing elbow both the fire alarm (located near the ceiling at the bow end of the cabin) and the CO detector (located on the companionway steps) went off about simultaneously.

Of course that was a gross emission of fumes and I don’t believe is the same as a subtle emission from say a gas heater with a small leak.

If one believes that by far the biggest danger is to sleeping persons my intuition is to put the alarms at bunk level in each sleeping space.

My absolute rule is to shut off all propane (and if I ever lose my senses and get a generator that as well) when we go to sleep. This applies to our travel trailer as well.

That does not cover the situation where one is motoring with someone asleep in the cabin (especially a grandchild down for a nap). It would not even have to be a leak, we once rented a boat with an aft cabin that sucked in fumes with a vengeance.

 

[shemandr]

After the dive boat disaster, I think it's best practice to have CO alarms and fire alarms in any boat with sleeping cabins. And the example with kids (Or other people) taking a nap below is a good one. Now with generators becoming more common, whether installed diesel or gas on the transom, CO protection is even more important. That's not to mention heaters, stoves and lanterns. Any open flame could be a source of CO.

 

[Kings Gambit]

We’ve noticed exhaust fumes entering the cockpit, to a lesser degree the salon, when motoring downwind in light conditions. The exhaust gets trapped in a kind of static draft at the stern, and wafts up into the cockpit. I suppose the CO in the exhaust comes with it, and could find its way below. That could conceivably affect someone sleeping in the salon or the aft cabin if it persisted long.

 

[Kings Gambit]

After the dive boat disaster, I think it's best practice to have CO alarms and fire alarms in any boat with sleeping cabins.

It might be that marine surveyors are now required, or at least encouraged, to recommend installation of CO units if there are none. Good point. He seemed concerned that we might sleep with the Espar running, which we have done.

 

[jssailem]

KG
CO is almost the same weight as Air. As such it has a tendency to blend with the air pretty much filling the whole room space. Concentrations continue as it displaces the oxygen in the air.

When we had the issue on Mahalo the first alarm to sound was the one in the stern close to the source of CO being blown into the cabin form the cockpit. Almost simultaneously, maybe a 5 second delay the alarm near the forward cabin sounded. We turned the Honda off and opened the cabin companion way and the forward V-Berth Hatch. With outside air blowing in the boat it took maybe 7-10 minutes for the alarms to stop. Eventually the alarms silenced and we were able to close up the hatches and go back to sleep.

It was a restless remainder of the night for me.

I would locate them where they are visible, separated fore and aft and near where you believe the first entry of CO might happen. They alarm based on the ppm of CO in the air.

 

[Hello Below]

Opinions?

for Richard19068.

I have a similar setup as the OP, an Espar furnace, propane range and obviously the diesel. Maybe a little cautious, but I have 4 CO detectors on my 33’ boat. Three fitted in the boat from the factory and one I added. I replaced the original 3 detectors when they expired at the 5 year mark ($ouch$). There is 1 each in the forward and after cabins and 1 in the salon. When a smoke detector gave up the ghost in the galley, I replaced it with a combination smoke and CO alarm with a 10 year battery. No more marine CO detectors that have to be replaced every 5 years for me. Approximately $40/ea times 4 over a 10 year period equals $16/year. Nuff said.

The colour, tasteless and odourless gas had a lethal effect on one of these sailors although the second survived. Neither of the men, nor the dog, were sleeping.

Sailors CO Poisoning

 

[Bob S]

Hard wired or battery operated?

 

[Hello Below]

Hard wired or battery operated?

If you are directing this question to me, the 3 originals (Safe-T-Alert - MTI) are hardwired and the added (Kidde) has a 10 year lithium battery.

 

[JamesG161]

Hard wired or battery operated?

My battery Alarms will almost wake the dead inside our H430 cabins.

Hard wired versions, required for Landlubber construction, are placed to allow quick escape routes from a home.

I would suggest its boat size cabin design areas per @Richard19068 post#4 above.

My boat meets those specifications on that post.
Jim...

 

[Benny17441]

Don't forget that CO detectors come with an expiration date. The capacity for the sensor to detect CO deteriorates with time. Refer to the manufacturer instructions and replace accordingly.

 

[Kings Gambit]

Thanks for all of your comments. As per usual for SBO discussions, I‘ve learned a lot about this topic. From the input here, plus looking over on-line literature, it’s the consensus that while CO as a pure gas is lighter than the air’s mixture of gases (99% nitrogen & oxygen; about 1% argon & carbon dioxide), it incorporates (diffuses) quickly when introduced. Thus, a detector should be positioned chiefly by its accessibility to visual monitoring, and by where the CO gas can reach it via air movements (i.e., not in “dead air” spaces such as corners). Not so much by its height above the cabin sole.

But now from a practicality measure the question is where might a hard-wired model be installed consistent with the above; i.e., where permitting direct connection to the 12-v battery? I can say there is no easy way to do this on the Bavaria as it would require running 3 sets of wires from the battery if installing 3 units, etc. One set perhaps for an installation in the salon but as for the sleeping cabins, a lot of (prohibitively) difficult and tedious work. So, I think I’ll have to use the battery-powered models which can be 10 to 15% more expensive, potentially bringing us to over $300 for three. (At least it’s not the usual thousand $$.) It would be worthwhile if the factory either install them, or provide access to direct-connect internal wiring, etc., allowing an owner to make such installations after purchase.

 

[sail sfbay]

Suggest a 10-year battery-operated CO detector like a First Alert C0710 that costs $20 each on Amazon. That is what I plan to purchase.

 

[jssailem]

First Alert C0710 that costs $20 each on Amazon.

That is what I bought for Hadley and we used on Mahalo At that price you can afford to replace them every 3-5 years never running afoul of out of date alarms.

 

[Kings Gambit]

That is what I bought for Hadley and we used on Mahalo At that price you can afford to replace them every 3-5 years never running afoul of out of date alarms.

Looks appealing. I don’t know whether or not to consider seriously the presence or absence of a marine-use statement or label. I note that it appears to be a household/home-use model.

 

[Hello Below]

Thanks for all of your comments. As per usual for SBO discussions, I‘ve learned a lot about this topic. From the input here, plus looking over on-line literature, it’s the consensus that while CO as a pure gas is lighter than the air’s mixture of gases (99% nitrogen & oxygen; about 1% argon & carbon dioxide), it incorporates (diffuses) quickly when introduced. Thus, a detector should be positioned chiefly by its accessibility to visual monitoring, and by where the CO gas can reach it via air movements (i.e., not in “dead air” spaces such as corners). Not so much by its height above the cabin sole.

But now from a practicality measure the question is where might a hard-wired model be installed consistent with the above; i.e., where permitting direct connection to the 12-v battery? I can say there is no easy way to do this on the Bavaria as it would require running 3 sets of wires from the battery if installing 3 units, etc. One set perhaps for an installation in the salon but as for the sleeping cabins, a lot of (prohibitively) difficult and tedious work. So, I think I’ll have to use the battery-powered models which can be 10 to 15% more expensive, bringing us to over $300 for three. (At least it’s not the usual thousand $$.) It would be worthwhile if the factory either install them, or provide access to direct-connect internal wiring, etc., allowing an owner to make such installations after purchase.

King Gambit, you have my interest as to where you can purchase 12VDC hardwired CO marine alarms cheaper than battery operated ones.

There is probably a multitude of solutions to your hardwiring dilemma, if you go that route. I will check but I do not believe that my hardwired detectors are connected directly to the batteries as for example the bilge pump is. They do have a separate unswitched breaker (push button type); but, if I turn the main DC breaker off I think they are also switched off.
Given the alarms draw in the order of 100 mA of current, tapping off any unswitched 12V source that is handy to where you wish to locate the devices should not cause a problem. An example may be a 12VDC power outlet. In my case I have 5 situated through out the boat including in the cabins.

I like the residential lithium battery operated alarms because they are readily available, they are much cheaper than marine hardwired, they have an end of life (EOL) of 10 years and the use zero boat supplied power. Although the hardwired models are relatively low current they still use in the order of 3 x 100mA x 24 = 7 Ahr/day of precious power. I added the First Alert combination smoke/CO alarm in the galley and unlike the many nuisance alarms I have had with the hardwired alarms, I have not had any with this one.

 

[Kings Gambit]

King Gambit, you have my interest as to where you can purchase 12VDC hardwired CO marine alarms cheaper than battery operated ones.

There is probably a multitude of solutions to your hardwiring dilemma, if you go that route. I will check but I do not believe that my hardwired detectors are connected directly to the batteries as for example the bilge pump is. They do have a separate unswitched breaker (push button type); but, if I turn the main DC breaker off I think they are also switched off.
Given the alarms draw in the order of 100 mA of current, tapping off any unswitched 12V source that is handy to where you wish to locate the devices should not cause a problem. An example may be a 12VDC power outlet. In my case I have 5 situated through out the boat including in the cabins.

I like the residential lithium battery operated alarms because they are readily available, they are much cheaper than marine hardwired, they have an end of life (EOL) of 10 years and the use zero boat supplied power. Although the hardwired models are relatively low current they still use in the order of 3 x 100mA x 24 = 7 Ahr/day of precious power. I added the First Alert combination smoke/CO alarm in the galley and unlike the many nuisance alarms I have had with the hardwired alarms, I have not had any with this one.

I was comparing two models from the same manufacturer, Fireboy-Xintex Model CMD5 at Defender Marine (and elsewhere). I investigated that model based on a PS report from 2002. Admittedly, a remark not based on an extensive price comparison of all, or even many, manufacturers and models. I didn’t question it b/c it made sense to me that inclusion of a long-lived lithium battery would add to cost, etc.