I have a 47' houseboat. The dock power is sometimes flaky. How do you tell when the power has gone out and come back later while you were gone. The reason I am asking is that I will have a freezer stocked with food and don't want to lose it all or want to know if the freezer has thawed and refrozen while I was away. I was thinking of freezing a vial that was half full of clear water. Then after frozen fill it the rest of the way with water with red food dye and freeze again. If I come back to a completely red.. or red on the bottom after settling, I know the freezer has thawed. Easier ways?