Ratio of grain to mash & sparge water?

[matt76]

I'm planning to be this black IPA at the weekend:
http://www.greatfermentations.com/fall-black-ipa-recipe

My plan is to halve it from 5.5UsGal (20.8L) to make 10.4L in the FV, and halve the grain from 14lbs (6.35kg) to 3.175kg.

But I've noticed there's no separate mention of water quantities for mashing and sparging.

To my eyes this looks like a lot of grain for the amount of water, even allowing for boil off and other losses.

Based on Palmer (and clibit's simple AG recipe!) I'd expect about 3L water per kg grain at mashing and another 4L per kg grain for sparging.

At this rate, for my 3kg grain I'd end up with about 20-21L pre boil - no way is half my water going to boil off in 60 mins!

So what gives?

Is this just a particularly stiff or dry mash? (I believe you need a certain amount of water in the mash to give the enzymes room to swim about converting starches to sugars)

Or is it a consequence of aiming for a higher OG and hence ABV? (i.e. you need more fermentables)

I'm limited to about 15L pre boil in my brew kettle so can reduce the grain more to suit if needed - but any advice on mash & sparge water volumes would be welcome!

Cheers,

Matt

 

[strange-steve]

Mash water is usually around 2.5 - 3L/kg, so in this case 7.9 - 9.5L, but sparge water isn't quantified in the same way. The idea is to mash at the above rate then sparge until you reach your pre-boil volume (assuming you are fly sparging). Do you know your expected boil-off rate and how much kettle trub? Add these to the FV volume to get the pre-boil volume.

For example if you boiled off 3L/h and you expected 1L of trub in the kettle then you would sparge until you had 14.4L in the kettle.

 

[matt76]

Well my last brew was 2kg grain, I used 6L for mashing and 8L for sparging, so 14L added in total.

I'm not sure about trub losses but after the 60min boil I ended up with about 11-11.5L in the FV.

At this early stage in my brewing career I'm just dunk sparging with a grain bag.

So scaling this up to 3kg grain, would I stick to about 2.5-3L per kg, and simply reduce the volume of sparge water?