Nope. Rating systems based on polars - which are VPP based - are a "simplification" of the real world that ignore important factors like waves (and a number of other tertiary effects on boat performance) . PHRF uses real world results - no simplification. Why you can build/modify/optimize a boat to any VPP rating system - giving you a VPP (rating) edge that is not based on real boat speed changes (ie you can make your boat rate slower then it really is). Whereas you cannot run this scam on PHRF. Sure PHRF has its problems too - for custom and low production boats where there is insufficient real world performance data - and infrequent (and too often sited) PHRF committee favoritism. If you think about how close these rating systems need to be to be deemed "fair"... predicting performance within 1% (6 seconds per mile or so)... its hard to get right.
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The Polars Expedition
- Thread starter Gamayun
- Start date
Note polars are not the "end point" to judge if your boat is "fully performing"... its a VPP based "starting point". You then need to go out into the real world and see what your boat can really do... keep notes... determine what your target speed/wind angle/sea conditions should be. There are more then a few examples of the initial VPP polars being "way off" for some boats on some points of sail - something you can find out on the water - or talking to someone with your same boat that has taken the time to document the boats "real world polars" (not the VPP polars that are just a starting point). If you really want to pull on this thread to watch it unravel... one really needs to have driver specific polars... and then there is wally. http://www.ockam.com/2013/05/02/the-wally/
PacCup PHRF moved to Tim eon Time (from Time on Distance). There is a pretty good case ToT is "fairer" ("fair" being a dangerous word to use... very dependent on what you think "fair" means). Though I am not so happy with ToT - as its hard for mere mortals to know how you are doing... as the time correction calculation requires knowing when boats finish... not like ToD where you can calculate time allowances in your head in a few seconds. A lot of racing is emotion based... and something you cannot grock intuitively, even if its technically "fairer", may not be best for maximizing participation.
WBChristie
New member
Bob groks that the boats with a higher rating seem to have an advantage....
How does the PHRF committee reconcile the SHTP results into the NCPHRF ratings.... or do they?
solosailor
New member
They do not reconcile as PHRF is based on crewed racing inshore..... not singlehanded racing offshore with a modified PHRF rating.
These are the what the PHRF rating are based on:
The Committee will assign ratings based on the following essential assumptions:
1. The racing will take place primarily on and around the central San Francisco Bay
2. The wind velocities will be an approximate median of the lesser winter wind speeds and the higher summer wind speeds
3. The ratings reflect the prevalent use of traditional windward/leeward courses with a minimum of reaching legs or random leg courses.
4. The yacht is in optimum racing trim and all normal equipment is on board
5. The hull bottom is fair and clean
6. The sails are in good condition
7. The propeller folds/feathers or the yacht has an outboard that can be raised clear of the water
8. The yacht is expected to be competently sailed
WBChristie
New member
Thanks for that... which leads to, who determines the modified PHRF ratings for SHTP?
WBChristie
New member
Haha! I’ve heard people say the SHTP should be called “The Olson challenge” but this puts a whole new spin on things!
Seriously though, how are the modified SHTP ratings determined, and are they ever “adjusted”?
solosailor
New member
The SSS used the PacCup rating system which modifies the PHRF rating based on displacement/length ratio, etc. (I could be misquoting) even after the PacCup moved on. It was similar to the mods used for the Certified Downwind PHRF rating. Not sure if there are any mods done the last few races.
solosailor
New member
Well certainly the O30 has had more entries than most other boat designs. They certainly have not won every time they race. 2x were in the 2000 edition and they didn't fare to well.
BobJ
Alerion 38 "Surprise!"
This forum apparently doesn't accept Excel files as an attachment. Gary, if you send me an e-mail, I'll reply with the spreadsheet that's always been used.
Long ago, SHTP skippers made the argument that changing the rating formula would affect their placement in the historical results. If the formula is changed, it's possible for future SHTP results to be recast using the existing formula before adding them to the historical results. But I don't know if current and future SHTP race organizers want to deal with that.
WBChristie
New member
Thanks...my email is gary@[gcbmarineservice.com]... remove the brackets.
As far a changing historical results, the O30 that won last year had a 3 second advantage over Bill Stange's O30 ..... so its already been done. Seems quite bizarre that a boat that has won the race multiple times gets a ratings break, but heavier displacement boats like Jim Kellams boat, a Spencer 35 has his rating dropped 37 seconds because he won the race?
Of course the weather (rhumb line or pacific high in play) has an effect, but for instance the well sailed Crealock 37 last year hadn't a hope of winning under the current rating system, which favors lighter planing boats.
Since I don't plan on entering again, my motives are to try and bring discussion to even the playing field for future races ... many enter this race because of its "run what you brung" Corinthian spirit type appeal and it would be sad to see more and more of the same boat being entered.
Oh, and by the way...the current race committee sail Olsons ...coincidence? hahaha
BobJ
Alerion 38 "Surprise!"
The three second difference was probably because that Olson 30 didn't carry a #1 genoa. It's not a modification by SSS - it's in NorCal PHRF's rules.
Many times over the years, the SSS board has stated "We don't want to get into the ratings business." Your last snide comment is a big reason why. You wonder if the SHTP ratings are ever adjusted, then in advance you suggest bias by those who would do it.
Many times over the years, the SSS board has stated "We don't want to get into the ratings business." Your last snide comment is a big reason why. You wonder if the SHTP ratings are ever adjusted, then in advance you suggest bias by those who would do it.
WBChristie
New member
6 seconds with the genoa. Come on, lighten up.... and how were those adjustments made? By the PHRF committee?
BobJ
Alerion 38 "Surprise!"
For all, NorCal PHRF recently refreshed their Rules and Regulations:
http://www.yra.org/PHRF/docs/ncphrf_rules_and_guidelines.pdf
(Gary's question is answered at section VII. 2. That adjustment has been the same for several years.)
http://www.yra.org/PHRF/docs/ncphrf_rules_and_guidelines.pdf
(Gary's question is answered at section VII. 2. That adjustment has been the same for several years.)
WBChristie
New member
You are not following, its 6 seconds between the two 030's 96 vs 102. 3 seconds for the headsail, 3 for the motor. So the point stands, the rating is 3 seconds different between the boats, both without motor
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