I believe you are right Gordon. In fact, I know you are. If it were colder than the water, it would be water.
If you put it all in the container, the hottest part of any liquid goes to the top.
(With the exception of frozen water. When it gets below 4*C it begins to rise again.) This includes the steam. If you put the tin foil on top like RyanO it holds the heat in and the area above the liquid water is hotter. The reason I have had better luck with steam, is because you can heat a smaller amount of water to a high temperature faster. Then the steam fills a larger container than the water did, making it easier to immerse the bow in the heat. Justin