Carver Owners Forum

During cruise and while piloting from the Bridge of our 1984-85 Carver 28 Voyager my CO2 detector will often pick up a reading and begin sounding an alarm. We have twin Mercruisers (GM 350s) and they are operating normally and are well maintained (fluids, filters, etc.) We keep all the windows and doors and hatches closed so I am trying to figure out how fumes are getting into the Main Cabin. The area under the refrigerator is partially open to the Bilge Compartment, so this could be the culprit, although it appears to be designed to be open. Or, this opening could have been a 'modification' from a prior owner and a it should be completely sealed. I can't find any reference in our books and manuals. In the interim I placed some flexible foam insulation under refrigerator opening, but the problem persists. Also, I typically run our Blowers while underway. Has anyone had this problem and if so, found a remedy? Any ideas how we might tighten up the cabin to shut down the CO2? What about the area under the refrigerator - should is be partially open? We would like to continue to operate in cold weather (and pilot from inside the Cabin) but don't want to fall over from fumes during a Winter Cruise (plus, the beeping of the CO2 alarm is very loud, even from the Bridge).

I am a novice boater, so don't take my level of boat knowledge for granted. Fire away with any comments and suggestions. Thanks!

How old is the CO instrument; they have a lifespan?

The detector is new within the past few months and seems to be operating properly. When we shut down the Alarm stops after a short time and the CO2 "reading' returns to normal (this detector reads out a CO2 level and sounds and Alarm).

That would be CO not CO2. Could be a few things. I assume you mean the CO detector in the cabin and not the fume detector who's sensor is in the engine compartment with the monitor typically at a helm. Under the right conditions, you could get a backdraft effect causing the exhaust to find a way in. It may also be an exhaust leak in the engine compartment. Assuming the new detector is working properly, it's critical that you find out what's causing the alarm. If you've got a battery operated CO detector at home that's portable, take it to the boat and see if its alarm gets triggered as well.

Good catch on the CO2. Of course I am referring to Carbon Monoxide.

The detector is a purchased Unit for the cabin that is also battery operated and seems to check out fine - again, operating normally in that it only sets off while cruising and then returning to 'no alarm' and normal readings ('no Carbon Monoxide present') once the engines are shut down.
Any thoughts on a good way to check for an exhaust issue? I am not seeing any smoke with the engines operating at cruise and removed the aft deck hatches in the slip and restarted the engines and am not seeing anything.
I even washed down the Bilge and Engine Bay thinking it could have been residual, but no luck.
Thanks for any input.

Couple questions:
1. Is your layout the galley to aft? So the fridge space you are talking about is close to the engine compartment?
2. Where is the CO detector located?
3. If you crack a hatch or window while underway does that help?
4. If your detector is battery powered, can you move it closer or further away from the galley and see if it takes longer to alarm? Can you use it to narrow down where the problem is coming from?
CO is no joke so use some caution. Common causes are the stationwagon effect when running. If that sliding door isn't tight, it's could get through there.
Calling Carver could answer your question about the bilges being connected. They would know what the original design was and are amazingly helpful at sharing build specs.

I would think if you don't hear an exhaust leak, its most likely a "station wagon effect" and the O2 coming in around the salon door or somewhere else with loose gaskets to the rear of the boat.
something to try, crack the front (bow) hatch just a bit and turn off the blowers at cruising speed. (you don't need to run them at cruise speed) this will give you a small amount of positive pressure in the cabin and should stop the alarm unless you do have an exhaust leak.

This boat does have the Galley at the aft on the starboard side and the refrigerator is near the engine bay (but slightly forward).

I can reposition the Detector and try it in several locations and will also look at the seals on the aft deck door and give the slightly open hatch suggestion a try.

These are excellent ideas and I really appreciate all the help and suggestions. A call to Carver may also answer the question about the open space under the refrigerator. It doesn't seem like it should be open, but it also does not appear to be cut out or rigged in any way.

I'll follow up with a report after some further analysis. Thanks again!

Your CO monitor should always be in the same proximity as where you are....that way it can sample the same air as you are breathing.This station wagon effect is very common with boats and can be extremely dangerous.The suggestion of cracking the front hatch while underway is a good one, positive pressure in the cabin is good....you will have to experiment to keep safe.

Now in the operators manual there may be an explanation of how to deal with such an event in your boat.

Hello all,

I too have this problem (and appears only while cruising) I have a 38’ With the galley more midship portside. I use two Battery powered CO detectors one at the galley and another repositioned in different spots to try to detect which detects faster (also a second also eliminated the variable that it’s a problem with the first detector). It freaks out my adult kids that this is even a thing (we just made the move to power from sailing forever - so lots of new things learned). I haven’t found the source either. However, thank you to the many Useful suggestions from other contributors.