The GameMaster's Blackjack School

This free course on blackjack and card counting was provided by the GameMaster, publisher of the GameMaster Online website. It is reproduced here in its entirety with permission of the author. The 24-lesson course is an excellent introduction to winning blackjack.

To start at the beginning, visit the Welcome page.

Lesson 21 - Beating the Double Deck Game - Part 1

by the GameMaster, reprinted with permission.
The Blackjack School is also available on DVD from the GameMaster's Store.

At first glance, it would seem only logical that a smart player will do better at a game that uses fewer decks, but that's not always the case when you compare double-deck games with six-deck games. A lot of variables come into play, not the least of which are the rules of the games, the minimum bet size required and the amount of scrutiny the games get from casino supervisory personnel. If you do not count cards, it's very likely that you'll be better off avoiding the double-deck games out there. I know some of you may be surprised by that comment, but I make it based upon the fact that many casinos have less liberal rules on their double-deck games, yet they require higher minimum bets. As a result, the casino's overall edge may be similar to that of their six-deck game, but you'll have to bet more on every hand for the privilege of playing. Because a non-counter cannot get a long-term edge over the casino, you'll just be betting more on a consistent basis and the casino will eventually get your $$$.

Now don't get me wrong here; if the rules are the same, a game using two decks will have a lower casino edge than one that uses six-decks, yet the strategies are almost identical. If the minimum bets are the same (or are at least within your comfort level), then go with the 2-decker. That's a key point, by the way. The proper Basic Strategy for a double-deck game closely resembles that of a four- or six-deck game, much more so than a single-deck game. The few differences between a two-deck and six-deck game with the same rules (dealer hits or stands on soft 17, double after split is allowed, etc.) lie mainly in splitting pairs and, since pairs are the rarest hands you'll get, the impact is negligible. I might be wrong about this, so check, but I do believe that the only change is to split a pair of 7s against a dealer's 8 in a double-deck game. In a six-decker, you don't do that. Not a hand you're going to see everyday, either way.
Note from the BlackjackInfo.com editor:
There are indeed only a handful of changes in strategy between the 6-deck and the 2-deck game. In a 2-deck S17 game: Split 77v8, Split 66v7, and Double 9v2. If the game is H17, also double A3v4.
My point is that you can move back and forth between DD and 6D games and not worry that you're playing improperly, but the big question is whether or not you should. We've already covered the non-counter situation, so let's turn our attention to those of you who do count. Even in this situation, the double-deck game isn't necessarily the hands-down choice and I'll show you why as we go along.
For whatever reason, many casinos treat their double-deck games as "premium" games, so they have higher minimum bets, may have less liberal rules, less favorable penetration and are usually watched more closely by the "pit critters", as we lovingly call them here. Some casinos seem to think that counters are showing up in droves at their DD games and carting off chips by the box load, but that's not necessarily the case. I know of some games that are very easy to beat, but they are few and far in-between. The reality is that beating the double-decker takes extra effort and some sharp play by the counter. But you came here for answers and I have them.
The primary advantage to playing a double-deck game is the volatility of the count. Unlike a 4- or 6-deck game, the running count, which is converted to the True Count (count per remaining deck) in a DD game can rise or fall quickly, but it's gone almost as fast, due to the shuffle. That's obviously good when the count is negative, but no fun at all when the count is "up". Things happen quickly in a DD game and the wise counter takes advantage, but it requires good skills at converting to the True Count and almost needs some ability to anticipate what's going to happen, while remembering that we never make guesses when counting.

The Key: Penetration

Because a DD game uses only 104 cards, versus the 312 of a 6D game, just a few extra cards of penetration can make a big difference in how well you can do at the game. In my Blackjack School lessons, I tell you that you're wasting your time if you play at a 6-deck game where less than 65% of the cards are dealt before the shuffle. In a DD situation, 65% penetration is very acceptable, 75% is fantastic and 80% or more is phenomenal. What you'll more likely find is penetration in the 50% range. Yep, they put together two decks and then use only one of them! I hate it when that happens.
But penetration is really important, so it's something you need to become familiar with. If you play a DD game where the dealer hits A-6, you may double on any first two cards, double after split, etc. and you use a 1-8 betting "spread" (I'll explain it later on) and the casino deals only 50% of the cards, your long-term edge as determined by simulations that I ran on Statistical Blackjack Analyzer will be about 0.64%. If the penetration deepens to 60%, the player advantage goes up to 0.95% and at 75% penetration it's 1.47%. That's not bad, you know.
Let's recap this so it stays with you:
Impact of Penetration
on a Double-Deck Game
Percent PenetrationTheoretical Player Edge
50%0.64%
60%0.95%
66%1.14%
75%1.47%
A "trick" I stress in my lessons is to leave the table when the True Count drops to -1 or lower, if at all possible. That can be fairly easy to do in 6-deck games and not so easy to do in DD games. Therefore, you have to pretty well accept the fact that you'll be playing in all counts, which makes the penetration factor even more important. We call this "play all" and the figures above were calculated under those conditions. By the way, you need to remember that simulation software plays Blackjack perfectly and we humans don't. That's why I use the term, "theoretical" player edge; that's about as good as it will ever be, but figure 10% less for purposes of reality.

Getting Started

If you have never played DD games as a counter, you need to do some basic planning first. While they aren't a world apart from 6D games, here are some differences to consider:
  • Many, though not all, DD games are dealt facedown and that requires you to count the cards in a different way.
  • Because it will be difficult to leave the table when the count drops, you'll need to learn more "negative" Basic Strategy variations.
  • Many DD games require the dealer to hit soft 17 (I'm going to assume that throughout this series), so there are some Basic Strategy changes needed. You can get them at www.blackjackinfo.com
  • With penetration being such a crucial factor, you should first check your local game to see if it's even worth the trouble. Verify the rules while you're there.
So, start doing your homework on this and I'll be back next time with a plan for how to bet in this game.

Questions? E-mail me at aceten1@mindspring.com and I'll reply personally.

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