While mariners and paddlers still use those and even simpler techniques for navigation, since then there are technologies developed to make life easier, providing your batteries are fresh.
Marine Traffic – This online site uses boat’s AIS data to mark their positions. You can use the site to track shipping if you’re planning a crossing. Track ship departure and arrival times and by clicking on the boat symbol, you can get info on the boat itself – what kind, speed, destination, a photo, etc. We use it to track freighters and tugs for surfing near Seattle. Like anything, it’s not always 100% accurate. So have a backup even it’s your own eyes.
Boat Beacon – An app that works with Marine Traffic, Ship Finder and other sites which allows you to track yourself or have others track you. A great tool for paddling in fog, at night or for loved ones to see how you’re doing.
Spot – These nifty devices allow for satellites to track you whether on-water or in the mountains anywhere (or most places) in the world. You can send regular and emergency messages to friends, mark waypoints etc so folks can track your every move. The devices are water resistent and float.