Re: Reasons for knowing TVMDCAW
Just because you own a calculator doesn't mean you shouldn't be able to perform basic arithmetic by hand (or better yet in your head). Knowing the basics allows you to not just place blind trust in your chart plotter/handheld but to use it as a tool.
Hardware fails, software has errors, people make mistakes. Although I am far likelier than my GPS to make a mistake when plotting my position, I have seen my handheld tell me I travelled 500 miles in a few minutes by bicycle.
Trust no one and keep your phaser handy ;-)