NavList:

I've been trying to teach myself celestial navigation working from books and online sources. I have a fundamental question and I fear what will be regarded as a dumb question but here goes. I understand if I take a sight I can draw a circle of equal latitude and then the books go on to say a need to take a sight of another celestial body to get a second circle and so I can place myself at one of the two places the circles cross.

But my question is this: as I know the GP of the body of my first sight and can calculate the azimuth why can't I simply plot the azimuth line and where it crosses the circle say that is a fix? `I suspect it is something to do with not being accurate enough particularly if I am closing the shoreline and because to do the calculations I have already assumed a position AP based on dead reckoning. 

I think if I was in the middle of the ocean and was confident in my DR then one sight would give me a good idea (circle crossed by azimuth) of where I was - or am I completely wrong and misunderstanding something?