solar noon is the time @ the shortest shadow. You don't need an almanac for that. It's got problems, but if you're lost on land with a digital watch and a stick it'll work pretty well.
Just seeing the shortest shadow doesn't tell you anything. You need a way to correlate it to your position on Earth. Having a watch (set to a known time zone) only tells you what time it happened, which is also pretty useless. You need an almanac (or some computation) to correlate what time solar noon happened on a given day with your longitude.