accurate?? hydrometer readings

I have been trying to get a hydrometer reading of my wort before the boil...err actually during the boil.

So I was wondering if it is even possible to get an accurate reading of boiling wort, or if the mere act of boiling makes it impossible.

Seems like I always get readings of 1.000 or close to it. So I thought, ok, add 42 pts to that and I've got it. Well, that hasn't been too accurate. What do you think?

So you're trying to read the hydrometer by dropping it in to a rolling boil? That's a pretty good way to break a hydrometer. You can probably just get away with pulling a sample out, taking the reading, then correcting the reading for temperature (which you would take before and after the hydrometer reading). I think "Designing Great Beers" has a procedure for this, you might check there.

Well if that's the case then regardless of the brew then it'll always be 42.

Simple answer is no you can't and why would you need to.

If you are looking to hit a gravity then you need to know the gravity going in and how much you've boiled off then you can calculate it.

Or take a sample, chill it and do a temp adjustment if you don't want to wait for it to chill to 60°F.

Unless you are doing full boils then you need to add water afterwards anyways so that would give you a completely different reading.

I am convinced that I don't trust the correction equations above like 110 °F or so. Just a gut instinct...I could be wrong, but since I have never seen how they derived the equations I am skeptical. There is something about it that bothers me....but it could just be me .

Best way imo (as has been mentioned), is just draw a sample out at the end of the boil and when it cools read it

Between the steam bubbles and the fluid motion, it would be impossible to get a valid reading.

Refractometers work well for that. Just drip one drop off your stirrer ontot he refracomter. The mass of the tool cools the drop instantly, wa-laaa, your sugar content.

Never have used a hydromthingy, why make it complicated. It's a wonder the boil water didn't crack it !

I would recommend you take a reading before the boil.

You need to cool the wort as the hydrometer is calibrated to read (usually) at 60F. As mentioned above the further your temp is from that the less accurate your correction will be. I use: http://hbd.org/cgi-bin/recipator/recipator/hydrometer.html

Then knowing your preboil gravity and knowing how much evaporation your boil produces you can determine if you need to add volume and how long you need to boil for to hit your target gravity.