Insanely high ABV. on my Quad

[Remos112]

I recently brew the following recipe:
7000Gr. Pilsener Malt
900Gr. Munich Malt
260Gr. Special B Malt
906Gr. D240 Candi Syrup @ 5min
31Gr. Challenger @60 min
8Gr. Saaz@ 60 min
23Gr Styrian golding @ 3 min

I mashed for 60 minutes @68C and nailed the predicted mash efficiency perfectly @70% wich isn't bad considering the huge grain bill.
Boiled, cooled everything went perfectly! Aerated with an aquarium pump and ceramic stone for an hour and pitched a load of Wyeast 1762 set the fermentation chamber to 20C and she ripped! Very wild fermentation, after fermentation slowed a bit I ramped up the temperature 1 C per day till 23C
Beersmith calculated the predicted FG @1.021 leaving me with beer of around 12% ABV. Wich I thought was the limit for 1762 anyway.

To my surprise I took a sample today, and it was fruity (esters) warm and toffee like, but no hot alcohol at all.(I've had hot alcohol with 1762 in the past) The real surprise was when I dropped the hydrometer in it read 1.012 I never expected it to finish anywhere near this low!
According to the brewersfriend calculator this gives me a beer of +/- 14% ABV. How on earth is this possible? The yeast is a couple of generations old, maybe it mutated in a better alcohol tolerating strain? It also gives me 88% attenuation which is shocking with an 1.110 OG. In fact this is the highest attenuation I have 1762 ever seen do.
Does anybody have some insight about what might have happened here?
Also the plans was to bottle it with Lallemand/Danstar CBC-1 a yeast strain GRJBowers made me aware of.
This is rated to tolerate 12-14% ABV. Will it still do the job on this monster? Or should I look for an even more tolerating yeast?

Any and all input will be much appreciated.
Thanks in advance, Remi

 

[Remos112]

Nobody experienced something similiar?

 

[YeastHerder]

On BS accuracy: I make a belgian tripel to about 10% ABV that finishes up to 5 points lower than BS predicts, varying a bit from batch to batch. That is less than your difference, but just letting you know I see differences sometimes too. As for an explanation, both yours and mine must mean we're off somewhere in our calculations or our temps hit. For example, if your 68C target was actually cooler than 68C (thermometers can be off target), then you'd have a more fermentable wort and get a lower FG.

On ABV tolerance: I've had decent (not perfect) luck using a fresh starter of the same strain as in primary to get bottle carbonation. However, I switched to kegging partly because I got tired of playing the carbonation lottery on high ABV stuff in bottles. So, if thats an option for you, it would bypass all the worries about yeast tolerance. You can bottle off your keg for easy sharing too.

On yeast drift: I've been growing the WLP500 in-house for maybe 10 brews (plus starters) saving it from the trub at the end of each fermentation. That should be some huge number of generations if counted by doublings. The strain has (hopefully) drifted from what it started out as, because I want the strains to drift into something uniquely mine. This must be what happened over 100s of years in ye olden European brewhouses, so now its happening in mine too. I figure if you brew the same thing every time, the changes in the strain should eventually settle to some new equilibrium. How you harvest yeast should act as a selective pressure (top crop, lower flocc; bottom collect, high flocc; collect at end of high ABV brew, push ABV tolerance up; and so on).

 

[Remos112]

Bottled the beer last saturday and it smelled amazing, lot's of banana, and it was dark as tar. Here's hoping it will carb.

 

[JacktardBrewmeister]

I know this is late but I have done belgian quads with Mangrove Jack M31 and M41 with successful results to the point of wining an award or two and getting an ABV average of 11~13.6%. I use a pound of coconut sugar in place of yeast nutrients and I tend to shy away from liquid yeast personally, since I am a lazy bastard. I hope it turns out well for ya but if you try again check out some Mangrove Jack yeasts for quads. Two packs has done me wonders (I have done 1 pack of M31 and 1 pack of M41 combined before with success) with my belgian quads in the past and I have given up on Wyeast and Whitelabs for my belgian style beers and stouts ever since. I still use them for other beers though, don't want you to think I hate liquid yeast or anything.

 

[Remos112]

9 days in the bottle now and it looks like it is carbing perfectly!