> Modern sextants can read the angle to a 0.1 minute level of accuracy, i.e. one-600th of a degree or one-tenth of a mile. In practice, actual accuracy to one-half mile is acceptable and quite good. The usual standard is accuracy to within five miles. The sextant (or octant) is meant to get the ship across the ocean. Once near the coast (20-100 miles) the more accurate techniques of piloting are relied upon for a safe landfall. The sextant is still the standard instrument for taking the observations required for celestial navigation.
One thing that helps with a pitching deck is that the horizon and object remain the same angle. Like a camera following race car, the objects move together.
> The Scilly naval disaster of 1707 was the loss of four warships of a Royal Navy fleet off the Isles of Scilly in severe weather on 22 October 1707.[a] Between 1,400 and 2,000 sailors lost their lives aboard the wrecked vessels, making the incident one of the worst maritime disasters in British naval history.[2] The disaster has been attributed to a combination of factors, including the navigators' inability to accurately calculate their positions, errors in the available charts and pilot books, and inadequate compasses.[3]
Yeah I get that it's important, I just didn't realize that angles could be meaured so accurately by eye at that time (especially on a ship that's moving around on even a moderate sea).
> I just didn't realize that angles could be meaured so accurately by eye at that time
Sextants have a bit of magnification (usually 4x, but sometimes 7x or higher). Higher mag allows for better accuracy at the cost of more shaking of the view.
https://www.ion.org/Museum/item_view.cfm?cid=2&scid=14&iid=2...
One thing that helps with a pitching deck is that the horizon and object remain the same angle. Like a camera following race car, the objects move together.