W is only protected from L by Rule 17 if L sails above L's own proper course, which it did not do. L is entitled to sail a proper course which makes W keep clear.

I don't see the contradiction. L is entitle to sail her proper course. 17 only limits L (if the overlap is from clear astern) from going above her proper course.  The appeal decision correctly found that L's proper course  was to sail toward the finish line and W didn't keep clear.
Proper course: "A course a boat would choose in order to sail the course and finish as soon as possible in the absence of the other boats referred to in the rule using the term...." 

Note, in a recent protest, We found that L could sail a course to gain position on other boats (not the W boat directly involved).

Rule 17 does offer W limited protection from L, just not to the extent you think. L is restricted to no higher than her proper course  which protects W from being luffed head to wind. I wish the rule were better understood by symmetrical kite boats to windward of asymmetric boats to leeward!

Stephen re: ”I wish the rule were better understood by symmetrical kite boats to windward of asymmetric boats to leeward!”

HA!  I wish the rule were better understood by Asymmetrical kite boats to windward of an Asymmetric boats to leeward! LOL

Antonio, rule 17 is a rule that uses “proper course”.  When I walk people through any rule that uses that term, I suggest they remember to do 3 things:

OK .. let’s apply those to rule 17 and the Case 46 scenario step by step. 

Rule 17 states, “..she shall not sail above her proper course ..”

OK .. so in rule 17 PC is a limit.  In other rules, PC is a test or trigger, but in rule 17 it limits the allowable course of the leeward boat.

Proper Course starts with “A” not “The”
It is,  “A course a boat would choose …”.  Def: proper course does not imply that there is a single solution (“the”), but rather that there may be a range of possible courses and that the course in question is among them (“A”).    

In English, it’s the difference between …

Remember to remove the other boat(s)
Def: Proper  Course includes the language, “ ..in the absence of the other boats referred to in the rule using the term.”.  Rule 17 limits the course a leeward boat can sail relative to a windward boat. Therefore, when analyzing PC in rule 17, you remove the windward boat.

In Case 46, that means removing Boat W.  So when you remove Boat W, you only have Boat L remaining sailing by herself.

Pulling all that together now …

Looking at Case 46’s scenario, removing Boat W from the picture, you now ask…, 

Boat L is sailing alone almost dead down-wind, but sailing along and not directly toward the finish line (and thus is sailing a longer distance than is necessary):

Q: Would turning to windward, sailing a shorter distance toward the finish-line on a faster point of sail, likely allow Boat L to finish the race faster and thus be a reasonable proper course for L?
A: Yes

Q: In doing so, is Boat L sailing above her proper course?
A: No

Q: Does Boat L break rule 17
A: No

Anthony Pelletier wrote: Note, in a recent protest, We found that L could sail a course to gain position on other boats (not the W boat directly involved).

Given the "finish as soon as possible" in the definition of proper course, would you mind describing the situation and elaborating on the PC decision, please?

Johan Bergkvist
Of course. First, let's get the full quote: "A course a boat would choose in order to sail the course and finish as soon as possible in the absence of the other boats referred to in the rule using the term."  That last part is important.
In the case we heard, we were not able to determine how the overlap was established. It seemed unlikely that L had gotten the overlap from clear astern. But neither witnesses nor the competitors could say for certain how L got the overlap. Therefore, it was necessary to consider whether rule 17 limited L's actions.
L and W were on Port jibe going downwind.
L was bow out and stated she wanted to come up to sail faster and establish a better position for rounding the leeward mark (get inside and approach on starboard jibe. This could give her an advantage on some boats that would be approaching from course left. We concluded that this was a course that a boat might choose to sail the course in order to finish as soon as possible even if W were not there. Thus, it was an acceptable proper course. We therefore didn't have to worry about how the overlap was established since L had rights to sail the course she chose even if it had been established from clear astern within two boat lengths. She had the right to determine the course she wanted to sail and could take W up--even if W thought HER proper course was to sail deeper.
The main point is that proper course doesn't mean the course you would sail in the absence of all the boats on the course, just the one being referred to in the rule--in this case, the W boat.
L can take into account all the usual things one would: where are the puffs?; how can I gain an advantage on my competitors? All the usual things are valid considerations in deciding proper course except gaining an advantage on the Windward boat. 

Johan Bergkvist

Said Created: Yesterday 22:15

Anthony Pelletier

Said Created: Today 02:28

I think Johan understood you to mean L could sail a course to gain a tactical advantage on rather than a faster position ahead of other boat.

He was pointing out that that was not necessarily sailing to finish as soon as possible. 

Yup, that clarifies it.

Yup.

No, not all

Yes

No, gaining a tactical advantage is not necessarily sailing to finish as soon as possible. 

No, only things that may lead to the boat finishing as soon as possible. 

John Allan spotted it too; that was exactly what I was thinking.

I disagree. 
The definition says “finish as soon as possible in the absence of the other boats referred to in the rule using the term." 
That implies to me that you can consider other boats not being referred to in the rule. 
I can think of cases where you might intentionally slow your progress around the course to harm the finish of a competitor close in points. But in general, finishing in front of boat X is faster than finishing behind boat X. The definition only excludes consideration of the boat referred to in the rule using the term. 

If they had meant “in the absence of other boats” they would have written it that way. There is no reason to add the last phrase unless the writers intended to allow tactical considerations with regard to other boats. 

John A and Anthony, I’m following along with your dialog and is it possible maybe you 2 have different ideas of what you mean when using the word “tactical”?

Ang,

Yes, I think its about words.

The point I'm driving at is that it is possible for a boat to 'win' or beat a boat other than the other boat in rule 17 by tactically engaging with her, so that you both go slower, which is not sailing to finish as soon as possible. 

I'm not saying that protest committees should be over alert about this, but if L comes in and describes a tactical advantage like this the protest committee has to ask themselves 'was that sailing to finish as soon as possible?'

I think we agree, John. As I said, I can think of rare cases where you would slow another boat down to gain a tactical advantage. That would not be sailing to finish as soon as possible and therefore not be proper course. 
However, if boat X is sailing to finish as fast as possible, I will finish faster if I am in front of X than if I am behind. 
Getting to the leeward mark in a position to round in front of a group of boats coming in on Port is a tactical decision that is designed to finish as fast as possible. 
Thus, that tactical consideration is fair game in deciding my proper course, in my opinion. 
I will amend my previous statement to "almost all of the usual things." 

Consider this scenario:

Position 1 - Blue clear astern of Yellow, Rule 12
Position 2 - Blue establishes an overlap from clear astern within two hull lengths, Rule 11, Rule 15 for a few moments, Rule 17. Blue ROW may not sail above her proper course.
Positions 3 and 4 - Blue sails above her proper course to force Yellow to luff Green who is tied with Blue in the series. Rule 16.1, Rule 11, Rule 17.  Blue breaks Rule 17 as her change in course is not the course she would sail to finish as soon as possible.

I agree that would be one of the exceptions to the rule that you can consider other boats on the course, for the reasons you mention. 
I do think it's a bit contrived: if the blue boat is so fast that it can sail through the lee of two boats from clear astern, I hardly think it's necessary for it to luff to slow down green. If blue is on the lay line, she will already get to round inside at the mark. 
But, consider the possibility that blue was right on or just below the layline. She might want to sail a little higher to make sure she rounded.  She might have done that even if yellow were not there, in order to finish as soon as possible. So, she's allowed to sail higher than yellow might like. 

One more scenario

Position 1 - Rule 12, Blue ROW, Yellow keep clear.
Position 2 - Rule 11, Rule 15 for a few moments and Rule 17. Yellow ROW may not sail above her proper course.
Position 3 - Rule 11 and Rule 17.
Position 4 - Yellow is quickly approaching slower boats and changes course to pass the slower boats yo windward of them. Rule 11, Rule 16.1, Rule 17.  Blue protests Yellow for sailing above her proper course. Yellow does not break Rule 17 as she is not sailing above her proper course.
Positions 5 and 6 - As soon as Yellow is able to pass the slower boats she turns back down.

Agree. At position 4-5, yellow’s proper course is to sail above slower boats, who, incidentally, could luff her even higher. 

Jerry, in your 2nd scenario, wouldn’t we be looking at rule 19 in the first instance since black is an obstruction to both boats who are overlapped and Yellow can choose to pass Black to windward or leeward?

Angelo,

Yes, rule 19 applies, but it doesn't change the rule 17 analysis.

BTW, What rule is B protesting for @4?

Ang and John,

Great observations.  I used a reach mark scenario because a boat's proper course may be open for wider interpretation on a run.  But, it would be better to have the slower boats on port tack for the Rule 17 scenario.  

John good catch, B was protesting RRS 17, but RRS 19 requires B to give room to the inside overlapped boat at the obstruction.

Jerry,

The point I was making was that @4, when B hails, Y is sailing no different course than she has been sailing at positions 1, 2, and 3, straight to the mark.

Maybe the hail at position 5 would make more sense.

Please consider

Position 1 - Rule 12, Blue ROW, Yellow keep clear.
Position 2 - Rule 11, Rule 15, Rule 17 - Yellow becomes ROW, the beneficiary of a puff, but must initially give Blue room to keep clear.  Yellow may not sail above her proper course.
Position 3 - Rule 10, Rule 11, Rule 16.1, Rule 17 - Yellow turns up to avoid the slower Black who does not keep clear, Black breaks Rule 10. As Yellow changes course she gives Blue room to keep clear. Blue protests Yellow for breaking Rule 17.  Yellow does not break Rule 17 as she was sailing her proper course.