Carver Owners Forum

We have a '96 370 Voyager with hard wired Co2 detectors, which I replaced last year with Fireboy-Xinex CMD6 units. My question is; Are hard wired Co2 detectors connected in some way to the audible helm alarms? I thought the alarms on the Co2 units were self emitting and that wiring was only for power.

The reason I ask? Today after coming off plane with a tail wind, the helm alarms went off, but there was no loss of oil pressure or overheating and both engines were running fine. After 3-4 minutes, the helm alarm stopped. Once tied up and engines were off, I checked engine room and felt inboard elbows, manifolds and transmission housings and all felt normal but there was a faint smell of exhaust in the salon area where one of the sensors is mounted.

If the Co2 sensors are not connected to the helm alarm, any ideas as to why the alarm would go off?

I've never seen a CO detector hooked up to a helm/engine alarm but you never know what a previous owner did. Maybe Hans owned the boat before and rigged something up. What you might have heard was a fume detector which monitors bilge gases. Those alarms ARE mounted at helms. But really, it could also have been an engine system alarm. Would help to know what engines you have; are they EFI, MEFI? etc. CO detectors can be pretty loud too so it may have indeed been an alarm going off in the cabin and you thought it was at the helm? If the salon door or a window was open, you could have had a backdraft bring exhaust into the cabin, or worse yet, an exhaust leak on board. Either way, you need to determine which alarm it was so you can take corrective measures for both health and mechanical failure reasons.

It's CO (carbon monoxide) by the way that is deadly and monitored by the detectors, CO2 (carbon dioxide) is harmless.

Hold'n On II wrote:Source of the post Fireboy-Xinex CMD6

Those are CO alarms....... that is one Carbon with one Oxygen and is probably what was triggered as you came off plane as the " station wagon effect", took over. Exhaust gases coming back into the boat due to air pressure changes as you slowed down with the wind....totally normal, something most boaters need to be aware of and good you have the alarms to remind you.

Do check around as noted for leaky exhaust fittings though to be sure.

Another reason not to travel in the salon unless well ventilated and the alarms are up to date and operating properly.

Just to add....most of the helm fume alarms for engine rooms are for explosives, which would be raw gasoline fumes......so if you find that is what alarmed check all your fuel systems fittings etc for leaks.

CO and unburned exhaust gas will also set off most explosive gas fume sensors in the bilge.

km1125 wrote:Source of the post CO and unburned exhaust gas will also set off most explosive gas fume sensors in the bilge.

That may be the case but the concentrations would have to be extremely high and remember your densities and sensor locations....I believe their ( fume detectors ) intended design purpose is for raw fuel vapors before starting engines and the same after refuelling.....barring any cross interference, which is another subject altogether from the original post.

bud37 wrote:Source of the post

km1125 wrote:Source of the post CO and unburned exhaust gas will also set off most explosive gas fume sensors in the bilge.

That may be the case but the concentrations would have to be extremely high and remember your densities and sensor locations....I believe their ( fume detectors ) intended design purpose is for raw fuel vapors before starting engines and the same after refuelling.....barring any cross interference, which is another subject altogether from the original post.

Not exactly sure what you're saying. Yes, those sensors are INTENDED to detect explosive gas at (usually) 10% of the lower explosive limit and calibrated for gasoline. But they are just "hydrocarbon detectors" and will also detect CO and any unburnt hydrocarbons in the exhaust and will alert at some "uncalibrated" level. I've had exhaust leaks and instantly triggered the fume sensor. Even though it wasn't a gasoline leak, it was good that I was alerted as the exhaust leak had to be fixed ASAP anyway.

Hopefully the OP finds his issue as something not dangerous.......

My '03 360 Sport Sedan had a CO detector below the helm. The mount and wires are still there, but the detector was gone when I got the boat. It looks like the same mount as the factory installed originals and there was an "extra" cover plate in one of the glove boxes.

Could the '96 Voyager be a similar setup?

Thanks everyone for your input. Sorry about my referral to Co2 detectors and not "CO" detectors

For what it worth; The engines are naturally aspirated 454XL's and to my knowledge, there are no fume detectors/sensors in the bilge/engine compartment, although there should be and which I plan to install. The blower was running and all salon windows and doors were open. CO detectors are located in the aft port corner next to the salon sliding door, the forward v-birth and port side guest bunk(s).

I am familiar with the the "Station Wagon Effect", which is why I wondered about the CO detectors and if they were somehow tied to the helm alarms. The alarm was definitely coming from the helm(s), as I've had prior engine shut downs for various reasons and the alarm(s) went off. Unfortunately, there are no corresponding lights or indicators as to which sender(s) set them off.

I suspect I may have a sending unit going out, or corroded connections somewhere. So I'd like to do some trouble shooting. I know you test gauge/sending units by grounding the sending unit and seeing if the gauge pegs. Is it the same for the helm alarms? If I ground an alarm sending unit, the alarm should sound? Given that I know which sender is an alarm sender and which is a gauge?

Do you know if you have transmission temperature alarms? Those usually don't have an indicator at the helm, just a horn. I don't know if these would be tied into the ECU for your year, and it's also possible a previous owner added something. A couple pics of the transmission would show if there was an alarm sensor on there or not.