Decoction Mash questions

[Thundercougarfalconbird]

So, I've been watching Braukaisers Decoction videos().
I'm trying to calculate a triple decoction mash for a dogfish 120. (16.5lbs of grain) and these Steps:
15min acid rest 95F
15min protein rest 122F
15min Gluten rest 135F
60min Beta sacrification 149F
15min Mashout 165F

The first equation already throws me off a bit:

Vmash=Mgrain(R+.32qt/lb)
R=water grain ratio in qt/lb

I'm confused as to what R is exactly, and how to calculate it. But for now lets guess its 1.68 because thats what braukaisers is.(his calculation is for 10lbs of grain. So he needed 20qts) So If I'm using 16.5 lets say my I need 33qts.

So, I heat my mashtun then heat these 33qts to around 95F and dough in and let it sit for 15min.

Now bear with me here and check my method.
The formula listed for decoction volumes is: (Using Fahrenheit, I assume T is temperature)

V=Vmash ((Ttarget-Tstart)/(Tboil-Tstart))

So my first decoction would be as follows.(Correct me if I'm wrong)

7.62= 33 ((122-95)/(212-95))

After adding 20% to account for evaporation,ect, my first decoction volume should be 9.14qts.

I bring it to a boil, but stop at 158-163F, pull the pot off the burner wrap it in a blanket for 15min amylase conversion, then put it back on the burner and continue heating it.
Boil 30min.
After this boil I add this SLOWLY to my mash while measuring temp to be sure I don't over shoot. Then I let this sit for 15min.

Now I do my second decoction:

4.8= 33 ((135-122)/(212-122))

After adding 20% to account for evaporation, ect my second decoction volume should be 5.75qt.

Boil 30min.
After this boil I add this slowly to my main mash while measuring temp to be sure I don't over shoot. I let this sit for 15min.

Now I do my third decoction:

6= 33 ((149-135)/(212-135))

After adding 20% to account for evaporation, ect my third decoction volume should be 7.2qt.

Boil 30min
After this boil I add this slowly to my main mash with measuring temp to be sure I don't over shoot. I let this sit 60min, stirring every 20.

Now I do my final decoction (mashout?):

8.4= 33 ((165-149)/(212-149))

After adding the usual 20% my final decoction volume should be 10.1qt.

Boil 30min. After this boil I add the decoction back to the main mash and let it rest 15min.

After the 15min are up. I lauter,vourlaf,batch sparge, as usual...

Any insight would be greatly appreciate(or acknowledgement that I'm doing this correctly would be awesome as well)

 

[WhiskeySix]

Sound like you've done your homework. My last brew was a brown ale. I did a double decoction. But I used Beersmith and it did all the calculations for me.

 

[Thundercougarfalconbird]

Edit: Yea all the numbers beersmith projects seem to be about .1-.3qts lower than my calculations. Also I wonder why it doesn't calculate my mashout temp.
I see beersmith tells me to fly sparge, do I have to or can I do a batch sparge?

 

[WhiskeySix]

Hmmm? It gave me a mashout. 10 min @ 168*. Also batch sparge option. I checked the options for triple decoction and triple decoction lager and they had mashout.

 

[Thundercougarfalconbird]

I mean it didn't have a mashout volume calculated.
Guess I just need to get to know my beersmith better