Cocoa powder vs. gravity readings

I brewed a Chocolate Robust Porter last week with 8 oz of dark cocoa powder added at the end of the boil. Fermentation seemed as vigorous as it usually is and trickled down after a couple days as usual. Today I racked to secondary and took a gravity reading and it had only dropped to 1.030 (from 1.069 OG). The sample tasted bone dry--certainly not what you'd expect for a 1.030 gravity, but there was quite a bit of cocoa powder in it.

Is it common for suspended cocoa powder to skew the gravity readings? Or, conversely, is the ale just tasting dry because of the bitterness of the cocoa powder?

At any rate I'll let it settle out in secondary for a couple weeks and see if the gravities come down. Here's the recipe:

Amount Item Type % or IBU
9.00 lb Pale Malt (2 Row) US (2.0 SRM) Grain 75.00 %
2.00 lb Chocolate Malt (350.0 SRM) Grain 16.67 %
1.00 lb Caramel/Crystal Malt - 40L (40.0 SRM) Grain 8.33 %
1.00 oz Williamette [5.50 %] (60 min) Hops 18.6 IBU
0.25 oz Chinook [13.00 %] (60 min) Hops 11.0 IBU
0.35 oz Target [11.00 %] (30 min) Hops 10.0 IBU
8.00 oz Dark Cocoa Powder (Boil 0.0 min) Misc
1 Pkgs SafBrew Ale (DCL Yeast #S-33) Yeast-Ale

Difficult to tell.
In theory undissolved matter in a liquid will not alter the gravity reading UNLESS it is impairing the free flotation of the hydrometer. I would let it sit in the primary for another week or so. Maybe give it a shake just incase.

Well it came down to 1.022. This cocoa powder is a real mess. Even after racking to secondary and letting it sit a couple weeks, it's still staying in suspension. It coats the hydrometer pretty good and I really have to rap the hydro against the bottom of the sample tube pretty hard to get the CO2 off of it.

I gave up on getting the gravity numbers I wanted and kegged it today. We'll see what happens--I think it'll be fine because it tastes plenty dry right now. I'm thinking the cocoa powder will settle as the keg crash cools. That first pour is going to be like mud...

I just racked my chocolate stout in which I used cocoa powder also and did not have the same experience. I added mine with 15 minutes remaining in the boil so It must have fully dissolved. I also only used 4 oz. It had a noticeable chocolate bitterness but not overwhelming and the gravity was at 1.022, which I believe is as low as it will get considering all of the unfermentables I added along with the cocoa.

Seems like a LOT of powder. I just tasted a Double Chocolate Stout today that had 1oz of unsweetened Coca and it was GREAT after 2 weeks of bottle carbing.

I added mine 5 minutes to the end of the boil.

I can see how 8oz might be messy.

No problem for me but I had only 12% of what you had. Should be interesting in a month.

I used 6oz of cocoa powder in a brew, added at the last 15 minutes, along with 2/3oz of chocolate extract at bottling, and it turned out pretty good. Very chocolatey. The powder never seemed to fully dissolve in mine, and I never could get rid of the chocolate sludge that resulted, it made it all the way to the bottle, but it tasted great.

How did the porter turn out?

hehe. I have a choc stout sitting in 2ndary w/ 1lb of cocoa powder & 1lb of carob powder added to boil. I was tempted to pour the whole 2" yeast/chocolate/trub batter at the bottom of the primary into a brownie pan and bake it - it looked delicious Definitely lost about a gallon of liquid tho. sg was about 1.030 on xfer to 2ndary. gonna add cpl shots of choc liqour at bottling too i think.