Hey whats up. A hydrometer is really a fundamental brewing tool. Even if your temps are off for a reading, you will know at least whether fermentation is done or not, or somehow stuck. If it is stuck or incomplete, your bottled beer may explode when they begin to ferment again. That being said, I am currently experimenting, as many are here, with whether a secondary is needed. Its seems to be popular opinion that the yeast cake won't really effect flavor even in extremely long cases. It actually needs to be there for at LEAST a week(10-12 days better) to remove certain undesirable flavors from the fermented beer. A beer solely in primary will clear out in a few weeks. Also, your beer is saved the exposure to oxygen when you rack to secondary. That's not to say my secondaried beers are great too, I see(taste) no real oxidation problems from the racking process. It seems that the aggitation caused by racking may help settle out particulate matter quicker and possibly more completely. Try it yourself and see what you like. I'm becoming a fan of primary only(3wk primary-3wk bottle condition), with the secondary reserved for strong beers that need conditioning. Happy brewing and welcome.