Should I scale down recipe? Help a noob.

[jts15]

Hi guys, I'm a noob. I did my first AG kit 2 weeks ago and it went great. I decided to do a recipe I found online instead of a kit this time. I bought all of the ingredients before I realized that the batch size is 6 gallons. I don't have a pot big enough for that (32 qt.). I boiled 6.5 gallons down to 5.25 on my first kit in 60 minutes.

Would you suggest that I scale the recipe down (AHS usually has 5.25 gal)? If so, how much?
The thought crossed my mind to just forge on with what I've got and just have my gravity higher.
Also, why the 90 min boil? I've always done 60.

Thanks in advance for any help. I tried to put this in Beersmith but it's a little beyond me yet.

Here is the recipe:
Oatmeal Stout

A ProMash Recipe Report

BJCP Style and Style Guidelines
-------------------------------

13-C Stout, Oatmeal Stout

Min OG: 1.048 Max OG: 1.065
Min IBU: 25 Max IBU: 48
Min Clr: 22 Max Clr: 60 Color in SRM, Lovibond

Recipe Specifics
----------------

Batch Size (Gal): 6.00 Wort Size (Gal): 6.00
Total Grain (Lbs): 12.90
Anticipated OG: 1.055 Plato: 13.47
Anticipated SRM: 35.3
Anticipated IBU: 36.1
Brewhouse Efficiency: 70 %
Wort Boil Time: 90 Minutes

Pre-Boil Amounts
----------------

Evaporation Rate: 15.00 Percent Per Hour
Pre-Boil Wort Size: 7.74 Gal
Pre-Boil Gravity: 1.042 SG 10.55 Plato

Formulas Used
-------------

Brewhouse Efficiency and Predicted Gravity based on Method #1, Potential Used.
Final Gravity Calculation Based on Points.
Hard Value of Sucrose applied. Value for recipe: 46.2100 ppppg
% Yield Type used in Gravity Prediction: Fine Grind Dry Basis.

Color Formula Used: Morey
Hop IBU Formula Used: Rager

Additional Utilization Used For Plug Hops: 2 %
Additional Utilization Used For Pellet Hops: 10 %


Grain/Extract/Sugar

% Amount Name Origin Potential SRM
-----------------------------------------------------------------------------
72.9 9.40 lbs. Pale Malt(2-row) Great Britain 1.038 3
7.8 1.00 lbs. Flaked Oats America 1.033 2
5.8 0.75 lbs. Chocolate Malt America 1.029 350
5.8 0.75 lbs. Victory Malt America 1.034 28
3.9 0.50 lbs. Crystal 80L 1.033 80
3.9 0.50 lbs. Roasted Barley America 1.028 500

Potential represented as SG per pound per gallon.


Hops

Amount Name Form Alpha IBU Boil Time
-----------------------------------------------------------------------------
1.80 oz. Goldings - E.K. Pellet 5.00 36.1 60 min.


Yeast
-----

White Labs WLP002 English Ale


Mash Schedule
-------------

Mash Type: Single Step

Grain Lbs: 12.90
Water Qts: 16.77 - Before Additional Infusions
Water Gal: 4.19 - Before Additional Infusions

Qts Water Per Lbs Grain: 1.30 - Before Additional Infusions

Saccharification Rest Temp : 154 Time: 60
Mash-out Rest Temp : 168 Time: 10
Sparge Temp : 170 Time: 60


Total Mash Volume Gal: 5.22 - Dough-In Infusion Only

All temperature measurements are degrees Fahrenheit.

 

[TeleTwanger]

multiply by .166 and subtract the result? You're scaling down from 6 to 5 so that's 1/6th less of everything..

 

[jts15]

I didn't realize it was that simple...thanks.

 

[Revvy]

90 minute boils serve 2 purposes, the main one is to blow off DMS

Dimethyl sulfide (DMS) is an organic sulfur compound present above its flavor threshold in most beers. Because of its low flavor threshold, 10 - 150 ppb, it is a primary flavor and aroma compound that makes a significant contribution to beer character, especially in lager beers. It has a characteristic taste and aroma of cooked corn or creamed corn.

DMS is created whenever wort is heated, by the breakdown of precursors found in pale malts. Under ordinary circumstances, most of the DMS that is created by heat is then evaporated during the boil. Some DMS is also removed during vigorous ale fermentations, which is why higher levels are often found in lagers.

Covered boil
Covering the brew kettle during the boil prevents DMS from evaporating, and results in high levels of DMS in the finished beer.
Slow cooling
Because DMS is created at temperatures below boiling, cooling the wort too slowly means that excessive levels of DMS can be created which cannot be evaporated once the boil has stopped.

So boiling for 90 minutes helps drive off the precursors to this...

Additionally a 90 minute boil is often needed to get down from a large volume or wort to 5 gallons...