The rules only require that the hail was made. It doesn't necessarily mean the hail must be proven to be heard.

There are many reasons why the hail may have been made but not heard. 

If I believe the hail was made and the protested boat is clearly aware of the incident then I normally don't get too hung up when they claim they didn't hear it! 

(Sometimes/often I'm suspicious that protestees claim they didn't hear the hail to get out of the hearing!)

(Equally, there are probably times -fewer- when the protestor says they hailed when they know they didn't. Not much we can do.) 

Maybe someone can link to the RYA case on the topic! 

Question: Did the right-of-way boat display a red flag at the first reasonable opportunity, as rule 61.1(a) required? If it did, then X on the port tack failed to keep clear of Y on the starboard tack and broke RRS 10. If a red flag is not required, the port tack boat must remain clear by rule 10.

Sail Canada Appeal 15:
A boat intending to protest must hail “protest” at the first reasonable opportunity, but failure of her hail to be heard does not invalidate her protest. The fact that a protestee did not know she was being protested is not, by itself, grounds for not hearing a protest.

There is a (maybe) interesting way to think about all of this .. which sort'a bounces around in my noggin from time to time. 

I first consider the OCS call by the RC.  There is no requirement for an RC to do more than make a sound signal and raise a flag.  1 boat might be over or 4 boats might be over .. still the RC just raises the flag and makes a sound signal. 

It is up to each competitor to know if they were OCS and act accordingly.  There is no right in the RRS that an OCS boat be individually notified that they are OCS. 

I think of OTW penalties in a similar way.  A boat "may" take a penalty when she "may" have broken certain rules under certain conditions.  

A hail of "protest" is not required for a boat, who thinks  she may have broken a rule,  for her to avail herself of an OTW penalty.  Yes, a hail and flag are required (in certain circumstances) if one boat wishes to be successful in a hearing before a PC ... but boats are expected to know if they broke a rule and act accordingly ... just as a boat must know if they are OCS when the RC isn't calling sail #'s. 

So, a boat must hail ... but there is no right to hear the hail ... just like there is no right for a boat that is OCS to be individually ID'd by the RC. 

As you can see this is not a fully flushed thesis .. but it is something that bounces around my noggin from time to time. 

"May" take a penalty means choose to take a penalty instead of retiring.

Peter,

Could you perhaps rephrase your question?