New brewpot, higher boiloff than expected

I just finished brewing NB's Tongue Splitter Pale Ale (AG).

It was my first brew with my new Concord 15gal pot. I started the boil w/ 6.5 gallons, but I ended up short. I had way more evaporation than I anticipated. You can see in the attached picture, I ended up with about ~4.25-4.5 gallons? (That's a 6.5 gallon carboy). I also ended up with A LOT of trub once it all settled. I plan to mark the line on the carboy and measure the exact amount after I transfer to secondary.

A few questions -

- Should I top off the carboy with some extra water? I also ended up over my OG (actual: 1.058, should have been 1.045). Should I boil this water before adding it to the carboy?

- I boiled in a 15 gal Concord pot. What kind of boil-off rates do other folks see from 15 gal pots? (I know humidity and burner are factors here, just looking for some other data points).

Thanks!
-SC

Did you take an OG reading? How was it? If it was high, topping off until you get to the right OG before you pitch the yeast is fine. If you've already pitched, I wouldn't top it up.

I get about a 2 gallon boil off on my megapot. I would never have guessed it was that high but I boiled plain water first for an hour to see, yup 2 gallons. Anyway that was in the middle of winter. I suspect when the summer humidity comes, I'll get less

My OG was 1.058, it should have been 1.045. So I was pretty high over. But yes, unfortunately I already pitched my yeast.

If the yeast is already pitched, I should leave it alone? From the looks of it, I could probably add a gallon of water to get back to where I should be.

If active fermentation hasn't started, you could probably get away with adding some top-off water and gently stirring - or you could just settle for a slightly more robust beer this first go 'round....

I just finished brewing an hour or two ago - active fermentation hasn't started.

When adding water, should I boil it first, and then let it cool down? Or is that useless, and I should just add cold water right to the carboy?

I boil off 2 gallons per hour. I boil for 90 min so I loose 3 gal.

No need to boil if you have good tap water

Thanks guys. I added a gallon of water and gave it a stir. My new gravity is 1.046, which is right where I should be (recipe OG: 1.045).

For my next brew, I'm going to start out with 7.5 gallons in the kettle and see how that goes. Looks like I got almost 2 gallons of boil off here.

Thanks again, beer saved!