[Kungsgeten]

Some people at the club play 2NT as a preempt with 5-5 minors or 5-5 majors. It seems to work okay but I need 2NT as strong in the systems I currently play. What do you think about a 3NT opening bid showing a two-suiter in the minors or the majors? Perhaps 6-5 either way? I know Gitelman plays (or at least played) 3NT as 6-5 majors.

[whereagles]

Fit odds with a 6-5 are like 95%, but you need some way to always get to the right fit. The problem is digging the 6-2 fit when you're 22 in opener's likely two-suiter.

With 3NT as MM you have 4m useable for clarifications, but with 3NT as mm/MM I'm not so sure you can always dig the 6-2 fit, so you might have a problem here.

Still, with 55 odds are like 90% so the 6-2 fit problem only comes up once every 20 openings, and even then you might guess it right.

I think it might work, if you don't mind the occasional bad score from missing out on those cases. Not clear how you can do slam bidding though

[Kungsgeten]

If using this method I guess 4♥ would be a forcing bid (so you have to bid 4m as pass/correct, even though you may know that opener has the majors). Perhaps something like this?

3NT--
4C = Preference, or knows that opener has majors
...Pass = Minors
...4D = Transfer (longer hearts)
...4H = Transfer (longer spades)
4D = Preference
4H = Slam interest in opener's lower suit
4S = Slam interest in opener's higher suit
4N = 6KCB
5m = Preference

But perhaps a way of asking for the suit combination is needed.

[mikeh]

For a while I played 3N as a very strong hand, 5-5 or better, either majors or minors. We had some science over it, and some rigid loser count/control requirements. It was sort of fun on the very few hands on which it came up, but we stopped playing it partly because it was so low frequency but mainly because it wasn't fixing a problem in the methods, and impacted our ability to play another toy: 4♣ as a namyats type bid in an unspecified but not solid major, and 4♦ as the same with a solid, no loser opposite a void, major. With that toy in use, we needed a 4-level minor pre-empt and 3N was the obvious solution.

The unknown major namyats does come up every now and then and it can be useful for responder to know immediately whether to worry about the trump suit. Again, science is available

Another problem, in ACBLand, is that 3N was, I think, illegal as we played it. So we played it in home games and at the local club with specific permission, and (iirc) we may have had it on the cc for a team trials once, but I don't think it came up.

[mgoetze]

When I played with gwnn, we agreed on 3NT as 6+ hearts with a 5+ minor (we had a 2-level opening with spades and a minor but not with hearts and a minor). The responses were: 4m pass/correct, 4♥ to play, 4♠ asking for a transfer to the minor, and 4NT RKCB for hearts.

Needless to say it did not come up.