H
Howard
This is a belated response to an earlier posting from a gentleman whose wife wanted to convert their ice box into a reefer unit. Until he did so, she intended to use DRY ICE to keep the beer a little cooler.I hope by now someone has smartened them up. As the dry ice takes up heat, its component CO2 sublimates from the dry to the gaseous state. CO2 is lots heavier than air. Assuming these naive folk press on with their suicidal intent, here's what will happen to them: (Note that I'm *not* speaking hypothetically here.) During the day, CO2 will accumulate in the bilges, rising just like water. The motion of air through the cabin, in likely combination with open hatches etc., will mix/spill sufficient CO2 from the hull to keep the atmosphere at shoulder height viable. At some point, they will have a night when they have closed in the hull, but it's still sufficiently warm that substantial sublimation continues. Now, with hatches closed, they retire to their bunks. Mixing and spilling of the CO2 from the salon ceases, and the relatively cold, dense CO2 now forms a definite layer somewhere below the level of their bunks. The dry ice continues to sublimate through the night and concomitently the CO2 slowly and silently rises to their nose level. First one and then the other inhales a lungful of CO2.The myth here is that they will somehow sense something wrong, and get up. The reality is that a lungful of "air" having a substantially elevated CO2 level will, in all likelihood, render each of them instantaneously unconscious. Until they die they will continue to breath increasingly pure CO2 and their heirs will inherit the boat.Discussion with several Naval personnel who have stepped into CO2-filled spaces renders unanimous this fact: there is no time to think, to do something, to step back out. One breath, and you're on the deck, unconscious. Mind, the sailors I spoke with were the lucky ones: they were wearing hand-tended lifelines and when communication with these men ceased, the repair party hauled them out. Sailors who go alone into compartments which are not "gas-freed" are usually brought out in a bag. Given the instant lethality of this situation, the Navy is slightly manic about gas-free safety. No one is allowed into a long-closed compartment without an air mask until a thoroughly qualified "gas-free engineer" has taken numerous air samples throughout the compartment and found it fit for entry. I love a cold beer, but using dry ice to cool your suds in a sail boat (or any other boat for that matter) is just plain stupid.