[Wainfleet]

I open 1NT with 13 HCP (playing 12-14) The bidding goes (P) 2♣ (2♠)
I am assuming from the overcall that partner has hearts and I have 4 hearts. I'd like to bid 3H - game invitational but what little I can find on 4th seat says I should not bid a suit at the 3 level. My choices are to pass or double for penalties. I don't understand why this is so. Would a double not normally be for takeout? We play transfers so don't play Phoney Stayman and given the spade overcall it is unlikely that partner is playing weak Stayman 5-4, so I would assume partner has 11+ HCP and a likely 8 card heart fit, and it does not feel right to pass that.

Can anyone help?

[jillybean]

I would double to show 4♥'s, a penalty double here seems to make little sense.
If unable to double, pass - I have already described my hand with my opening bid.

[Wainfleet]

jillybean, on 2022-April-02, 09:01, said:

I would double to show 4♥'s, a penalty double here seems to make little sense.
If unable to double, pass - I have already described my hand with my opening bid.

Thank you

[Gilithin]

By default:
After 1NT - (P) - 2♣ - (2♠), X shows 4♥, Pass denies 4♥.
After 1NT - (P) - 2♣ - (2♥), X shows 4♥, 2♠ shows 4♠, Pass shows neither.
After 1NT - (P) - 2♣ - (2♦), 2♥ shows 4♥, 2♠ shows 4♠, X shows good diamonds, Pass shows none of these.

After 1NT - (P) - 2♣ - (X), there are various systems. For example (simple): 2♥ shows 4♥, 2♠ shows 4♠, 2♦ shows good diamonds, XX shows good clubs, Pass shows none of these; or (complex): 2♥ shows 4♥ without a ♣ stop, 2♠ shows 4♠ without a ♣ stop, 2♦ shows good diamonds, , Pass shows a ♣ stop with Responder's XX being a re-ask, Pass shows none of these. This one needs some discussion with a regular partner.

[DavidKok]

I think this is not at all standard. If partner bids Stayman that is not an invitation to bid at the 3-level. You may very well apply your standard takeout/penalty agreements over interference (although I've found that some people only play those by responder, not by opener) but I would not assume taking action over interference is expected.

[smerriman]

Wainfleet, on 2022-April-02, 08:42, said:

We play transfers so don't play Phoney Stayman and given the spade overcall it is unlikely that partner is playing weak Stayman 5-4, so I would assume partner has 11+ HCP and a likely 8 card heart fit, and it does not feel right to pass that.

Why not? If partner has that hand, they're not going to meekly pass out 2♠ - they'll keep the auction alive, then you can show your hearts.