This really was my first year snowmobiling. I have gone out with my husband and friends about 5 times this winter. I'm still a beginner and a bit nervous - the others laugh at me. My question is how do you tell or test water to be sure it's completely frozen before crossing it with your snowmobile? My husband just says - you just know. Well I don't, and I don't want to take any chances either. How do you tell? Am I being too cautious?