You are correct that for some reason that CO dangers were not mentioned on this thread--although they have been mentioned a number of times on this list server in some detail. Since several of us are MD's we may have taken the dangers for granted--sorry. The thread sort of evolved to were the generator was stored and placed, not as a primary thread about generators or exhaust in general. The boat's engine exhaust can be as dangerous as the generator, although the danger may be slightly less with an outboard.
Although this is primarly about airplanes, I do believe at all boaters should read this article--even if you don't have a generator--it is one of the best on CO:
http://www.avweb.com/news/aeromed/186016-1.html It discusses the limits of detectors.
I believe the best detector is the CO experts 2004 model. It allows for low level cummulative tracking--and that is where dangers lie in boaters in pilot house boats and in airplanes.
http://www.coexperts.com/ (incidently it is available for less at other sites)
I won't go into the physiology on this post, unless someone wants that specifically. Just remember that the CO detectors need to be changed every 2 to 4 years--that many household and RV type detectors are not accurate enough (the article explains why they were "dumbed down" because of too many "false" paramedic runs. The other very important fact is that CO is bound into the hemoglobin with a much greater affinity than oxygen. The CO is released very slowly, and even with low levels will increase to a lethal level with time. Unfortunately in my practice I saw some deaths from CO--and a number of people who had chronic CO poisoning--from riding in their cars/in their houses in Los Angeles Basin.
We put the generator on the swim step or engine bracket--NEVER in the cockpit. The exhaust points down wind--and we anchor by the bow, assuring that the bow is pointing into the wind--exception is in river with current opposite the wind. I am not comfortable with the generator on the pilot house roof or foredeck--only outside of the boat. We have several CO detectors--a couple of the cheap NightHawk by Kiddie 4AA battery units, with LCD read out--and the CO experts by our bunk.
As for Lake Powell--the principle deaths were houseboats where the generator exhaust was trapped under the transom and for the most part involved youths who were swimming, slidding into this area with high CO concentrations (up to 7200 PPM). 36 of the nonfatal CO poisonings at Lake Powell occurred inside boat cabins, and eight of these were in boats on which CO detectors had been disabled because of repeated alarms. There the exhaust was pulling into the boats. All houseboats on the lake have been modified. This is well summarized in the CDC MMWR of Dec 15 2000. There was also an epidemic of "Teak surfing" where the people hung onto the swim step and were towed directly--the exhaust quickly overcame these people and they died or drowned. This is specifically outlawed on many lakes. All of the incidences I am aware of with death are where a victum was in the water, on the swim step area or in an aft seat of a cockpit, where very high levels of CO can be found (one instance of 27,000 PPM CO on a ski boat where a young girl sumcubmed in short order from an idling ski boat engine exhaust) I am not familiar with this specific case on Lake Powell, and I would appreciate if you would put the citation on this thread for my records.
Certainly CO is a very dangerous gas, and we should all be aware of it--However the use of a Honda EU2000i is not any more dangerous than built in generators if used properly. There are a number of cases where boats rafted next to a boat with a generator running, and CO overcame the people in the boat without a generator--so be careful where you raft up! Although Diesel engines produce less CO than gas engines, a diesel can still produce liethal levels of CO.