Bidding Over One Club - BOOC

Probably the single most used card in the bidding box is the 1 call.  (And for sure the least used is the 7NT card.)  Below is the treatment we use when the opponents open one club...

    Double    Transfer to diamonds (or 16-18 balanced)
    1    Both Majors
    1 or 1      May be a 4-card suit with 6 + HCP
    1NT    Top and Bottom Suits: Spades and Diamonds
    2    Two Lower Suits: Hearts and Diamonds

The Major Suits
Part of our BOOC bids are similar to the Michaels convention, which always promise at least 5-5 in the two suits.  Our agreement is to use Michaels with 5-5 also, but with a guarantee of perhaps 13+ points.  BOOC is used with lesser hands, often with 4-4 or 4-5 in the majors and only 7-12 points, certainly not enough strength to push the bidding to the second level.

Overcall with One Diamond to Show Both Majors
This is an artificial bid and must be alerted... The description is that it shows both majors, but not necessarily 5-5 in the two suits.

Either of these hands would qualify:

Hmmm... okay, but what if you actually have a diamond suit, or maybe a diamond suit with one of the majors?

Double with Diamonds
Although the double is a transfer to diamonds, showing at least a 5-card suit, the doubler may also have a 4-card or 5-card major.  Here is a typical hand:
Top and Bottom Suits
We do not use the traditional 1NT overcall.  Instead, we show two suits:  The top and bottom unbid suits.

Two Lower Unbid Suits
A jump to 2's shows the diamond suit, but it also promises a heart suit.  The two lower unbid suits.

BOOC allows us to show any single-suited hand, and all two-suited hands.  We give up the ability to show a balanced hand with 15-17 points.

Strong Notrump
Although most of the time the double will be a diamond suit, we also use it to show a strong notrump hand.
    Double, (Partner expecting a diamond suit) and then rebid 1NT - 17+ points
NOTE:   BOOC can also be against Precision players who open 2 with a club suit.