double problems

I follow basic strategy at site blackjackinfo.com

6 Decks, S17, DA2, DAS, ENHC, Early surrender
Estimated House Edge for these rules: -0.08%

There are said not to double 11 vs 10 or 11 vs A

but bjmath.com says there to double both.

What to do

Addition to that at http://www.blackjackinfo.com/bjtourn-doublechart.php
double charts give win odds for example 2,8 vs 9 49,38% (less than 50%!!) But 11 vs 10 is everywhere over 50%

What to do.Im very confused.Could anyone help me?

With ENHC rules it is correct not to double 11 vs 10 or 11 vs A because the dealer could still have a blackjack. The chart from bjmath.com refers to hole card games.
The chart from blackjackinfo.com does also assume hole card and gives percentages of wins,losses AND pushes.So a play doesn't need to produce over 50% wins to be called for.What you really want to know is expected value,which is for doubles : (win%-loss%)*2.
For 10 vs 9 doubled it's about 15% which is better than the 12% edge you get for just hitting.
I hope things are clearer for you now.

Francis Salmon

Tell me how can hand winning probablilty can be higher in doubling than hitting?
In double u can only can afford 1 card instead of hitting when u can correct your game when double card would have been 2 for example.

Mayby hitting winning odds are 65%(example)
Doubling lowers it to 58% but when we double we win average 16%(2*8) instead of hitting 15%.
Is it more realistic?

I would assume doubling offers a better long term bet as when you win you win double your original stake. If you stick to just hitting you will only win your original bet.

Without the math getting too complicated if you only won half your doubles, you would have had to win all your hits to have the same amount of cash in your bankroll.

Nobody ever said that winning probability is higher for doubling than for hitting. Forget about winning probability and start to think in terms of expected value (EV).In order to figure out EV you need to know the loss probability as well and because of possible pushes the 50% barrier that you seem to refer to all the time is meaningless.
Again: EV is win%-loss% and in doubles you just multiply this by 2.
EV tells how much a particular play yields (on average) as a percentage of your original bet and that's the key number.

Francis Salmon

Can we double 10 vs 11 at high count? What abaut variations?

Before going any further,it's crucial that you understand the concept of basic strategy properly.Counting cards is useless when you don't know how to play the hands. You should also be aware of rules variations and the way they affect BS. Variations of strategy based on the count is the last thing you have to learn.
Counting cards is primarily aimed at detecting advantage situations and knowing when to raise your bets.This alone is enough to be a winning player. Strategy variations come only as a supplement.
Anyhow, in ENHC there is no index for doubling 10 v A.

Francis Salmon

I think some of the confusion is due to the information you are looking at. The link you gave previously was to the % of time a hand wins if you double. The link is part of the tournament strategy section. This information is useful for tournament play, but can be misleading for normaly play. It is not the same information basic strategy is based upon.

Play strategies with card counting provide an advantage over the long term. Tournaments don't have long terms, therefore they are played differently.

For advantage play you have to focus on EV (as Frances stated). EV and the % a hand wins are not the same thing.

I would encourage you to forget you even saw the chart you linked to. Instead focus on an EV chart. Stanford has great charts in ProBJ that are very helpful in understanding how strategies are created.

Hope this helps