Semi bluffing means to place a bet on a hand that is not the best at the moment but has real chances for improvement and may become even the strongest on the next streets. A good semi bluff is a very powerful weapon. The only think you need to consider is: if the chance your opponent to fold is really very small, the semi bluff is not the best choice.
For instance, if you play with short stack, you can bet or raise (going all in) on the turn in case you have a strong drawing hand. In other words, you can use the classic semi bluff. For example: If you have an Ace of clubs and a King of clubs, there are Jack of clubs, 5 of diamonds and 6 of spades revealed on the table, the turn is 10 of clubs, there are $ 200 in the pot and you have $ 200 stack as well.
In this case you can absolutely go all-in if you play against one opponent since your winning chances in most cases will be enough for a “positive” call in answer to your opponent’s bet and your attack can make fold many marginal hands which may be stronger than your hand during the showdown if you don’t improve your hand on the river.
In case your opponent has a Jack of diamonds and 9 of diamonds, after your check, he most probably will attack..Then you will be forced to call having 18 outs i.e. 41 % winning chances. In this case:
0, 41 × 400 – 0, 59 × 200 = $ 46
In other words, this call ($ 200) will bring you a profit of $ 46 per hand comparing to a fold.
In case you attack first and your opponent folds, in 15 % of the cases your profit will increase. In 15 cases out of 100 you will win a pot of $ 200 and in the rest 85 hands you will have 41 % winning chances. Your bet in this case should be equal to:
0, 15 × 200 + 0, 85 × (0, 41 × 400 – 0, 59 × 200) = $ 69,1
In other words, the semi bluff bet of $ 200 in this situation will bring you a profit of $ 69 per hand.
Generally, in order to play with drawing hands you need to have a two ended straight and overs i.e. a combination which is at the edge of a “positive” call when the bet is comparable to the size of the pot. To use the semi bluff with weaker hands is not recommended, especially if you are not an experienced player – in this case the semi bluff may become a very dangerous weapon.
Taking into consideration that there is only one card to be revealed, your drawing hand is not to be considered that strong anymore and if you decide to attack with such a hand that will be a pure bluff.