I do! I do!
It was pointed out many years ago in one of the sailing rags I used to occasionally write for that there is a piece of equipment that is readily available, inexpensive (in fact you likely have one) and quite reliable at sniffing out leaking propane. The same unit, recalibrated, could work for detecting carbon monoxide. It operates on the principle that carbon monoxide alone doesn't segregate from the other divers gasses and vapors that internal combustion engines spew into the air as the result of their combustion of fuel at somewhat less than 100% stoichiometric efficiency. Along with the CO there will be residual oxygen, CO2, some soot and hydrocarbons that are easily detectable by the device. So, rather than detecting CO directly, it relies on detecting the products of incomplete combusion, from which the operator can infer that CO is also present. One caution about using the device is that, like driving or operating on someone's eyes, one shouldn't use it if one has a cold, allergies, or if one is drunk. It doesn't slice or dice, but it is capable of distinguishing among all kinds of gasses and vapors.
Ok, so what is this wonderful device? It's commonly called Natural Olfactory Sensing Equipment (N.O.S.E.)
Sorry, I couldn't resist. A blurb to that effect appeared in the late 1970s, just after the very memorable April 1, 1976 issue of SAIL magazine heralded the appearance of the polyestermite. Shortly thereafter newbie fiberglass boatowners (the boats being fiberglass, not the boatowners) began calling their local boatyards, frantic that this new gribble would eat a hole in their polyester palace.
But serously, Nurse, yes, if you forsee operating any IC engine in a confined space, which you shouldn't even think of, then install a CO detector.
Quinn
