Mashout/Sparge advice sought (limited space in tun)

[MTW]

I'm planning a Rochefort 8 clone for my 9th all grain brew. I've done three tripels (though not a darker Belgian) before, which have pushed the limits of my 26L coolbox tun in getting a 22l batch size. For those, I decocted some of the mash to bring the whole lot up to 76C after the main infusion, possibly with a slight top up of boiling water too IIRC. I've always batch sparged until now and know my rough efficiency that way. Fly sparging would mean a bit of an unknown in terms of efficiency, for now.

The Rochefort 8 clone I'm going for (pretty much the same as the winner of Herman Holtrop's widely reported competition to clone it) calls for a 3L/Kg mash, which means I'm certainly going to have to decoct portions again if I want a mashout.

I'd be grateful for any advice on my options as I see them:

1. Reduce the batch size to 15L at the most, which gives a mash volume of around 19L for this recipe. Achieve the mashout purely by top up of around 7L @ 100C, leaving only another 7L or so to sparge.
2. Squeeze as big a mash as I like into the tun. Achieve a mashout purely by decocting portions and fly sparge after.
3. Squeeze as big a mash as I like into the tun. No mashout, fly sparge.
4. Medium batch size and mash size; no mashout; batch sparge
5. Medium batch size and mash size; mashout via part-decoction-part top up; batch sparge with the remainder.
6. Don't bother with the recipe's demand for 3L/Kg (and go with one of the other options above).

Is this the moment to start fly sparging, or should I choose one of the options that is more know to me in batch sparging?

By the way...here's the recipe scaled to 15L, plugged into Brewmate, for any wider thoughts. I'm not planning to do a protein rest, which I'd have to do via two step infusion, Thanks in advance:

Rochefort 8 Clone
Belgian Specialty Ale

Recipe Specs
----------------
Batch Size (L): 15.0
Total Grain (kg): 5.213
Total Hops (g): 61.50
Original Gravity (OG): 1.080 (°P): 19.3
Final Gravity (FG): 1.012 (°P): 3.1
Alcohol by Volume (ABV): 8.90 %
Colour (SRM): 30.8 (EBC): 60.7
Bitterness (IBU): 28.8 (Average)
Brewhouse Efficiency (%): 73
Boil Time (Minutes): 90

Grain Bill
----------------
3.750 kg Pilsner (71.94%)
0.563 kg Caramunich II (10.79%)
0.300 kg Candi Sugar, Clear (5.76%)
0.188 kg Flaked Corn (3.6%)
0.188 kg Special-B (3.6%)
0.150 kg Candi Sugar, Dark (2.88%)
0.075 kg Carafa II malt (1.44%)

Hop Bill
----------------
39.0 g Styrian Golding Leaf (4.2% Alpha) @ 75 Minutes (Boil) (2.6 g/L)
15.0 g Hallertau Tradition Leaf (3.5% Alpha) @ 30 Minutes (Boil) (1 g/L)
7.5 g Hallertau Tradition Leaf (3.5% Alpha) @ 5 Minutes (Boil) (0.5 g/L)

Misc Bill
----------------
7.5 g Coriander Seed @ 5 Minutes (Boil)

Single step Infusion at 66°C for 90 Minutes.
Fermented at 16-24°C with WLP540 - Abbey IV Ale


Recipe Generated with BrewMate

[fego]

Sounds to me like you should be fly sparging. It's not as difficult as you might think and only requires the crudest of equipment to be effective plus you're likely to improve your efficiency too.

Using gravity, set your HLT above the tun. Get a roll of foil and stab a few dozen small holes in it and lay it over the grain bed. Allow the liquor to trickle on to the foil so it doesn't disturb the grain bed. Allow an inch of liquor to build up above the grain and then open the tuns tap and collect in a jug. Recycle it until clear then leave the tun tap flowing into the boiler. The key is then to keep the inlet travelling at the same speed as the outlet to the boiler. This suspends the grain bed and rinses the grain evenly.

Doesn't have to be foil, can be a tin lid,a chinese takeaway box etc, anything that stops the splash really and then allows the liquor to flow in slowly. Don't forget to stir the HLT frequently to ensure even distribution of temperature (it's colder at the tap).

[MTW]

Cheers. My 'HLT' is actually two separate stock pots, which are also used in tandem for the boil. (I have tandem chiller coils too.) One has a ball valve, the other not, so as long as I can keep the first one topped up, should be possible. Good tip about keeping an even temperature throughout, ta. I usually drain the tun into an FV or the second pot (to get it warming up ASAP) before the whole lot is through, keeping an eye on volumes.

It has made sense to batch sparge with this set up until now. A bit simpler. I will have a fellow brewer with me for the first time on my next brew, so it might be a good time to try a fly sparge, with an extra pair of hands. I did briefly do a baking-foil fly sparge when I was short on volume, last brew, just for a couple of litres.

Would a lack of mashout really matter? Do certain combinations of grains need it more than others?

[Deebee]

hmm. I think i would basically just empty the mash tun completely before then closing the tap and adding the first batch of sparge water. stir, let stand etc.
i have never just topped up my MT after the mash and hit efficieny of around the 80+ mark

If you did intend to batch in your normal way i think i would even consider recucing the mash volume to 2-2.5l/kg

[Dave S]

There's also nothing stopping you doing a 3 way batch - i.e., three top ups instead of two. I'm intending to do this when I get round to, either a stronger than 1060 brew or a longer than 23l length.

[MTW]

Thanks everyone.

I've been thinking about these responses and various options, and I'm thinking I could test something different out next week on a tripel. I'd like to keep the mashout. I'm thinking I will recirculate a litre after the mash, drain the minimum amount that will let me get enough top up of boiling water in to get it all to 76C, duly do the top-up, stir, stand to settle, recirculate, drain until the excess falls to an inch above, and fly sparge the rest.

That way, I keep the greater fluidity brought about from being firmly up to 76C or so in the grain bed and stop the enzymes in their tracks, but still fit it all in and avoid a messy/awkward decoction. I know these Belgians are sometimes OK to dry out a bit if the enzymes carry on in the runnings before the boil, but there are significant sugar additions in there anyway (especially my tripel) and the mash should be low enough.

I'm thinking that's a plan...