Bilge/Motor Room Blower Exhaust Port?

[GordMay]

Originally Posted by Extemporaneous

Come to think of it, most if not all had very good exhaust systems in these rooms, some even having almost one entire wall of motorized dampers behind louvers which opened when the temperature rose beyond a set point. Can't remember if there was CO detectors or not. Gord would likely know if CO detectors in Generator rooms are standard or not.

Yes Generator Rooms & Enclosed Parking Garages are generally required by Codes to have CO/NO2* Monitors & Alarms, which control automatic** exhaust fans (or continuously operating exh. fans).

* If diesel-powered vehicles will be present, Nitrogen Dioxide (NO2) sensors will also be required.

** A Basic Sequence of operation
Normal Mode: The exhaust and supply fans shall be controlled by the carbon monoxide detection system. At 25 -75 ppm, fans will operate until the carbon monoxide levels drop below 50 ppm. An alarm will be given in the event carbon monoxide concentrations reach 150 ppm, for more than 8 minutes.

Additionally, all buildings of residential occupancy which contain a combustion appliance or a storage garage must have a CO detector, located in the service room and adjacent to the bedrooms of the suites which are adjacent to the service room. Similarly, CO Detectors are required adjacent to the sleeping areas of any suites which are adjacent to a garage.

Since CO has roughly the same density as air, CO sensors should generally be mounted in the “breathing zone” — about five to six feet up from the floor.

[Sandero]

First of all, last I knew the combustion of my engine took place in the cylinders and the exhaust gases were taken out via the exhuast system through the muffle and out the transom close to the water line.

My engine blower does little more than provide cooler air, and exhaust the hot air from the engine room. Where is the CO coming from in this set up?

You gotta think this one through guy.

[RBEmerson]

The point is most of the time there is little or no carbon monoxide to cope with, but if things go wrong... not so good.

What could go wrong? How about a hole in a hose, a loose hose clamp, mixing elbow failure (BTDT), an exhaust manifold hole, a blown gasket - the list goes on and on. Keep in mind, too, that flex pipes leading from the fan can and does wear through (BTDT, too), meaning the discharge now vents somewhere other than outside of the boat.

Heck, even if carbon monoxide weren't an issue, general bilge funk, when it happens, isn't all that much fun to smell, either. Venting into the cockpit just isn't a good idea.

[GordMay]

I was merely answering Extemp.’s question.

I believe that the NNMA currently requires a CO detector in accommodation spaces for certified boats.

Exhaust system leaks, the leading cause of death by carbon monoxide on boats, can allow carbon monoxide to migrate throughout the boat and into enclosed accommodation areas. Regularly inspect* your exhaust system and ensure that all exhaust hose clamps are doubled and secure. If you see water staining on your manifold it means that gases as well as water are leaking. Repair it immediately (a well tuned engine produces less CO than a poorly maintained engine).

*Annual Checklist:
* Replace exhaust hoses if any evidence of cracking, charring or deterioration is found.
* Inspect each water pump impeller and the water pump housing, and replace if worn. Make sure cooling systems are in proper working condition to prevent overheating and burn through the exhaust system. (Refer to the engine and generator manuals for further information.)
* Inspect each of the metallic exhaust components for cracking, rusting, leaking or loosening. Pay particular attention to the cylinder head, exhaust manifold, water injection elbow, and the threaded adapter nipple between the manifold and the elbow.
* Clean, inspect, and confirm proper operation of the cooling water">engine cooling water anti-siphon valve (if equipped).

Other CO poisoning etiologies:

It has been generally assumed that CO poisoning was not possible outdoors, however one recent fatality was that of a man working in the cockpit of his sail boat, with a small generator running on the dock. The CO drifted down into the cockpit and killed him.

Blockage of exhaust outlets can cause carbon monoxide to accumulate in the cabin and cockpit area - even when hatches, windows, portholes, and doors are closed.

Exhaust from another vessel that is docked, beached, or anchored alongside your boat can emit poisonous carbon monoxide gas into the cabin and cockpit of your boat. Even with properly vented exhaust, your boat should be a minimum of 20 feet from the nearest boat that is running a generator or engine.

Slow speeds, or idling, can cause carbon monoxide gas to accumulate in the cabin, cockpit, or even in an open area. A tailwind (force of wind entering from aft section of the boat) can also increase accumulation.

The "station wagon effect," or backdrafting can cause carbon monoxide to accumulate inside the cabin or cockpit when operating the boat trimmed at a high bow angle, with improper or heavy loading, or if there is an opening which draws in exhaust. This effect can also cause carbon monoxide to accumulate inside the cabin, cockpit, aft deck, and bridge on power boats, when protective coverings are used and the boat is underway.

CO Exposure Limits
35 ppm - Maximum allowed by EPA outside for 1 hour
200 ppm - Noticeable symptoms
800 ppm - Serious symptoms and even death
1200 ppm - Immediately dangerous to life and health
6400 ppm - DEATH in 10 minutes

I believe defjef is an Architect., whereas I worked for an Engineering firm.
The following dramatization might illuminate our differing points of view.
A Few Good Architects at AMNP

[bobfnbw]

Originally Posted by bobfnbw

Our endeavour 40 has a thermostat adjusted 4" blower mounted high in the engine room with intake and exhaust on the port side of the cabin using 4" duct.
Haven't done any heavy weather sailing yet, but the PO said he had no problems with leakage. The ports are covered with large plastic clamshell covers. Would have to take a lot of grey water to take on water. Would be nice to have covers for them, but do not. I plan on changing out the blower for something a bit quieter and less vibration one day, and using new duct. I also want to change the plastic clamshell vents to stainless, but its not a priority. Got lots to do before I can get to that.

Well, be careful of what you say, might come back to haunt you.....
pulling all the wiring out of the engine space right now as the engine is still at the shop. Also pulling the old fiberglass type sound insulation. The wiring on our center cokpit endeavour, along with the exhaust hose, and both ventilaion ducts, go thru the port side, between a bulkhead 6" deep, and out to the port side.
Yesterday, as I pulled wiring thru a small access hatch above the fridge box, I found another small panel I didn't know what there, under the galley cabinets, counter hight. I had to pull it off as all the screws were siezed... oh oh I thought as I yanked it off... it was for the exhaust 90 deg elbow going aft. Seems the exhaust runs along the top of the counter behind a small bulkead. There was some leakage previously, but all the bulkhead, as well as the 1x1 strips it attached to, were wet rotted, and bad. I believe, although not entirely sure yet that this was coming in from the vent areas. There is also a hose for shore plumbing or a deck wash down there, and a cockpit drain, didn't have time to fully diagnose where it was coming from yet.
I was going to rebuild the box anyway, but now its a priority. Water leaked behind it, im sure theres rot there too.
Smell was not to good.... lol. Glad I found this now. Needed access there anyway, the engine panel is there, as well as much of the a/c and d/c wire runs from the old panel in the engine space. All to be rerouted out of the engine room.
I would like to reroute the exhaust hose as well, but don' think there is any other way to do it.

Bob