Posted 2011-March-28, 21:08
It must be a splinter because you could show actual diamonds by bidding 3♦ then 4♦ (the first diamond bid starts off being 4th suit forcing but after your second bid, it shows 6/5 in spades and diamonds). And it must be a splinter for clubs because if you have a splinter for hearts you would have bid 4♦ right away instead of 1♠.
3♥ is not really a good bid, because it doesn't help partner to know when to bid 3NT. You bid 3♣ to help partner know whether to bid 3NT, and gives them a chance to give some mild preference, so you know whether they have a void or a doubleton, since if they raise to 4♥ after 3♥ they could well have a void heart but any other place to play seems worse.
If opener's clubs and diamonds were reversed, responder would be very pleased to bid 3NT after a 3♦ bid.
If he had one less heart and one more spade, he would have to bid 4♥ after a 3♥ bid, and if opener's clubs and diamonds really were reversed, you'd be missing out on a good 3NT.
The added benefit of bidding the strong 3-card minor instead of repeating the hearts is that the auction can proceed:
1♥ - 1♠
3♣ - 3♥
3♠ - 4♠
If opener has three card spades and responder has five, you won't miss your spade fit. But if it starts 1♥-1♠, 3♥, responder will almost always have to bid 4♥.
Don't forget to always raise with three cards immediately with a weal (11-14 HCP) hand. (i.e. 1♥-1♠, 2♠)
I ♦ Transfers