Not comparable

Because there is extra information (the presence of a biddable heart suit) which is not shown in the 1NT bid
North will have to pass throughout

If you check Law 23A for the definition of the comparable call:

A. Definition

A call that replaces a withdrawn call is a comparable call, if it:

1. has the same or similar meaning as that attributable to the withdrawn call, or

2. defines a subset of the possible meanings attributable to the withdrawn call, or

3. has the same purpose (e.g. an asking bid or a relay) as that attributable to the withdrawn call. 

As Nick commented:

"hands that bid 1H" are 4+ hearts and 6+ points (broadly speaking).

"hands that bid 1N' are ~6-9 points and a spade stopper (broadly speaking).

Even though 6-9 is a subset of 6+, the difference in suit definition (spade stopper vs natural hearts) means that these are not analogous bids.

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A 2H bid (whether it's a negative free-bid, or a positive free-bid) would define a subset of possible meanings, and thus be fine under 23 A 2. 
Showing 5+H is more specific than showing 4+H, and either having a range of ~5-10, or a range of ~10+ pts is a tighter definition than just 6+.

A negative double of 1S typically shows values to respond (~6+ pts), and tends to strong imply at least 4Hs. So this would also be a comparable call, despite not really defining a subset of the possible hands.

HI, I am training some directors at our club and one of them asked me this question :  

On a bidding, where a pair has bid to 4H and partner asks "4C" ( meaning Ace ask) not accepted by opps. Would 4NT Blackwood  be acceptable as a comparable call ?

Thank you for your opinion.

Happy New Year

Helene Labreche

YES it is comparable

That is an example of a replacement call with  "the same purpose"

Unless (highly unlikely) there is doubt as to whether 4C was intended as ace asking

Hello,  I have a question about comparable call.  I was asked how I would rule this one and could not answer it.  So here goes:

Dealer is East who opens 1 S !

South bid:  4C  (ace asking CRO)

W passed

and North bid   1H !   director is called and ask if E accepts the underbid  and E accepts !.

I was asked what would have been a proper or comparable call for N had E not accepted the underbid?

I could not answer that..so I am asking the  forum so we can be more knowledgeable about this.

Thank you

Helene Labreche

East Coast Bays Bridge Club

Hello,  I have a question about comparable call.  I was asked how I would rule this one and could not answer it.  So here goes:

Dealer is East who opens 1 S !

South bid:  4C  (ace asking CRO)

W passed

and North bid   1H !   director is called and ask if E accepts the underbid  and E accepts !.

I was asked what would have been a proper or comparable call for N had E not accepted the underbid?

I could not answer that..so I am asking the  forum so we can be more knowledgeable about this.

Thank you

Helene Labreche

East Coast Bays Bridge Club

Hi Helene

That bidding looks odd
ASking for aces immediately when nobody has bid except an opponent??

If it makes any sense south would have a humungous freak with something like a solid 10-card suit, three singletons and a total of two aces

Anyway there are two scenarios, which can be ascertained by talking to North away from the table

1   North was responding to ace asking bur wrote the wrong number 1 instead of 4
In that case 4H is "the same purpose" and is comparable

2   North was bidding hearts naturally being oblivious to the bidding so far
In that case 4H is "the lowest sufficient bid specifying the same denomination" and  the bidding continues without restriction. Note that applies even if the replacement bid is not comparable but the result can still be adjusted if the offending side gained assistance through the infraction (Law 27D)

Another point is Should North indicate (at the table) which of the above applies?
I would say emphatically NO
South must have to guess what North was doing withn the 1H bid
And if North WERE to give any indication (which could be hard to avoid) then Law 27D would likely apply

Thats how I see it. Its a tricky situation and I would like to see any other views

Nick