Hi I brewed it on saturday. I did it alone after a bicycle ride (my girlfriend was working and my brew-friend was sick) and everything was surprisingly smooth... I like brewing alone, I thought it was going to be sad, but actually I was more focused.
My grain absorption calculations are spot on but... I'm not doing my water calculations right. I had 4.2L of boiloff rate! (las time I had ~3.8L and the previous one ~4.5L)
This can't vary that much using the same kettle, same burner and same everything!
The problem is my kettle is too small, so I have to make calculations for water additions during the boiling and the volume of water changes with temperature (cubic expansion of water). If you add these small variations to the mix + the hops absorption (in the hop spider) it's science fiction that the numbers match reality. But anyhow, you can always adjust by adding tap water to the fermenter before pitching the yeast, can't you?
I calculated a final volume of 12L (10L batch + 2L trub) and OG 1050 and I got 11.5L and OG 1052, so... yep, everything but the boiloff rate or the measurement of the water I poured was exact.
My next improvement has to be a bigger kettle so I can avoid all those tedious calculations and I can put all the water at once, at the beginning, at ambient temperature where the volume match (now I add boiling water from a kettle and warm water from the tap 1L at a time until I reach the initial temp and volume).
I think a 25L one would be perfect for my 10L batches... where can I find an uber-cheap 25-30L pot in Sydney?
Other advantage of having a bigger kettle is I will be able to measure the pre-boil gravity, which right now is also science fiction (because I add water while boiling, even more tedious calculations needed).
I also made another mistake... I calculated the IBUs based on the descriptiong of the Alpha Acid my supplier had in his website, but the actual hops I used were from a newer hop-batch with 13.8 instead of 12.8 % Alpha Acid, so instead of the 34.84IBU I calculated, I will have: 41.45IBU which I think with two extra gravity points is still on the range. I will have a very very slighly stronger beer, no big deal.
I've made several improvements for this one:
1- I've kept my thermometer all the time (but during the boiling) in the kettle with an improvised-but-clever-system: a paper clip and a clothes peg!
2- I've improved my "thermal insulation" for the mash adding a folded blanket on top of the insulated bag I used before. I did an 80' mash, I stopped every 20' to check the temp and stir a little and I didn't need to turn on the burner until the last time. After stirring for 5' I lost 1.5ºC !! For the last 3 beers I've had a consistent shitty 68% efficiency, what could you expect with the equipement I have... the good thing is it is a known constant now. <- good.
3- I've improved my chilling time from 3 hours to 45' by using an inmersion chiller (form ebay, I don't have tools here to do it myslef) and a pond pump <- total investment 70$
4- I've improved my "fermentation temperature control" using the T-shirt method (https://byo.com/mead/item/1084-make-me-sweat-cool-tips-for-hot-weather-brewing
). I put the fermenter into a rubber basket/bucket (6$ from bunnings) with 10cm of water covered with an old t-shirt. Then I put the pond pump inside the bucket with a tube/hose to the top of the fermenter.
Since saturday evening I've been able to keep a constant temp of 20º switching the pump on now and then. This morning the airlock was bubbling a lot and it was already at 22º so I put one esky block inside the bucket and left the pump running. Today it's going to be warmer, I hope it works... let's see what I find when I go back home...
Last time I made some kind of IPA without caring for the fermentation temp and it turned ok but it has two problems: not hoppy enough and it has a fruity taste, probably because of the high fermentation temperature. I've already drunk 3 or 4 of it and I didn't have headache or anything, I expect it doesn't have fussel oils (it wasn't so hot when I brewed it 3 weeks ago), but from now on I will try to take care of the temp while fermenting.
Depending on how this one goes, I will move to brew belgian saisons (up to 29º !!!) or I'll look for a small fridge and a temp controller. <- I will be staying in Sydney 1 more year, maybe it's worth to buy one... I will have to fight with the enemy in that case (the enemy = my girlfriend)
This wednesday I will do the dry hop (I brewed on saturay): 30g Citra, 30g Chinook.