Posted 2013-August-25, 17:07
Hand #1
North should reevaluate the responding hand after the direct ♠ raise by South. If South's raise generally guarantees 4 trumps, then you're looking at least a 10 card fit. Adding value for either shortness (3 for the singleton ♥) or trump suit length (1 for the fifth, 2 for the 6th trump), the North hand is worth about 12 opposite partner's opening bid. Most folks will just blast to 4 ♠ on those kind of values.
If you decide to invite, the question is what are your tools over the raise to 2 ♠? If you play Help Suit game tries, then any new suit bid over 2 ♠ asks for help in cutting down losers in the suit bid. Here after a 3 ♦ Help Suit game try, South with ♦ Ax would carry on to 4 ♠ as that holding ensures no more than 1 ♦ loser. The other tool often used is a Short Suit game try. Instead of bidding a suit needing help, any new suit bid shows shortness (singleton or void). Normally, the ♠ raiser carries on to game if his/her values are primarily outside the short suit. Here, after a 3 ♥ Short Suit game try, South can see that there are no wasted values in his/her hand. So even though it's a very minimum hand, South should carry on to 4 ♠. Most partnerships will decide to use one of these tools
Using either of these methods, the partnership can decide to use either 2 NT or 3 ♠ as the traditional power game try (i.e. bid game with a maximum, subside in 3 ♠ with a minimum). North really doesn't have the type of hand to use a power game try in this hand. But if he did have such a hand, South would decline to bid game and place the hand in 3 ♠, if necessary.
Hand #2
I'm assuming you are playing 1 NT = 15-17.
The contract you want to be in is 3 NT.
If 3 ♣ is invitational, then South absolutely has to carry on to 3 NT. South's hand is a maximum -- 17 HCP -- and has some nice placed intermediate cards (i.e. 10s, 9s, 8s) in addition. All 3 side suits(♦,♥,♠) have sure stoppers in South's hand.