help converting extract to partial mash recipe

[drunkinThailand]

I would like to brew a belgian chocolate stout recipe I saw online, but would like to change it to partial mash.

I have limited choices of base malts as I live in Thailand. I could just use a pale 2-row malt, orI was wondering if using "CHÂTEAU 45-EBC ABBEY® Malt - Castle Malting" or "Weyermann - Abbey Malt".
Here is the recipe as is

6.6 lbs CBW® Pilsen Light LME
.75 lb Dark Chocolate Malt
.75 lb Caramel Malt 90L
.25 lb Roasted Barley
.25 lb Carapils® Malt

I am still a new brewer so want to keep to partial mash as opposed to all grain to make sure that even with a not so stellar efficiency I will have enough fermentables.

So I was thinking cut it down to 3 pounds of Muntons Light Dried Malt Extract and then using 6 pounds of grains, one of the two mentioned above.

I do partial mash BIAB in case that matters.

thanks for any advice

 

[DromJohn]

See:
Brewing grain substitution chart

From the chart, 2-row pale makes the most sense if you are trying to match the above recipe.
The Castle Malting Weyermann Abbey malts seem close enough to substitute for each other. Both are darker than 2-row pale with stronger flavors. While rational for a Beligian stout, Castle is recommended to be no more than 25% of the mix, Weyermann up to 50% rate.
As a new brewer, I recommend the 2-row pale for this batch. Then experiment with the Abbeys in subsequent batches.

6.6 lbs LME = 8.8 lbs grain
3 pounds of DME = 5 pounds grain
8.8 - 5 = 3.8 base grain, + 2 lb specialty = 5.8 lb grains

So, either drop your base grain down to 3.8
or drop your DME to 2.88 lb.

If you have to buy in whole pounds, then drop the DME because it stores better.

 

[drunkinThailand]

Thanks for the help.

When I'm only substituting the base grain for the extract, why to count the specialty grains in the weight? Is that because now that I'm mashing them they count as well, but when doing straight extract they are only steeped and not mashed?

 

[chickypad]

He wasn't counting the specialty grains in the conversion he did for you. He was assuming that you get a decent efficiency of around 75%, in which case your original plan has too much grain/extract. The 3 lbs of DME you plan to use is the equivalent of 3.75 lb of LME, leaving 2.85 lb of LME that you need to replace with base grain (or about 102 gravity pts). Unless you're only planning about 47% efficiency then 6 lbs is too much grain. 3 lb of DME + 4 lb of grain is more what you need if you have an average efficiency in the 70-75% range. The specialty grains stay the same converting all extract to partial mash.

 

[drunkinThailand]

ah, now i understand. thanks for the clarification