PHRF Help please

Please post any questions or comments regarding the class association rules, here.

Moderators: sderby, Tim Bosma, Tom Elsen

dave
Posts: 727
Joined: Fri Jan 02, 2004 10:39 pm
Location: Little Rock

Post by dave »

That last sentence is unfortunately correct. All PHRF [ and other politics] IS local.

Allan. The question about spinnaker max hoist is covered in the GYA link that I included before: Appendix C, 3a. It is at least a starting point, if something of the same nature doesn't exist in your local rules.

I know that you aren't one of the "potentate" PHRF board members that I was referring to because you care enough to come to this site and ask the proper questions, and you are to be respected for that! Too bad ALL the others aren't as fair and balanced. PHRF would be a far better program.

Dave
@last
Posts: 15
Joined: Tue Aug 03, 2004 7:05 am

Post by @last »

Dave,

To answer your question LMPHRF number for j-24's last year was 168 so we spot them three. There are 8 registered but in all truth I don't know how many of these two groups ever meet-LMPHRF is such a big geographic area and many of the S-2's I listed race in fleet one, Holland, MI where in the wed night beer can racing they have their own OD start. I do one very informal race a year which happens to include a J-24, but any defiences in my results thusfar with the boat rest on my shoulders and not the boats or the rating gap. Also as mentioned ealier kudos to Allan for taking what seems to be a very enlighted approach to this whole deal and doing it in the first place, as Tom mentioned this stuff runs on volunteers such as yourself so Kudos.
Allan Fisher
Posts: 4
Joined: Wed Mar 12, 2008 4:09 pm

Post by Allan Fisher »

This is what we are thinking of doing, between the 3 - 7.9's. (At this time, no one else is really complaining about the 168 rating.)

We have 3 Velocitek GPS units which we can swap over to the 7.9's. The units will record their tracks and speed, and afterwards we can download all 3 into one program on my laptop, which will overlay them on top of each other where we can see what has happened and get speed comparisons between them.

Since it is the downwind speed that is of concern, we can have them start up wind and time the differances between each racing dead-downwind on a 2 NM course. (no jibing or reaching so that we try to eliminate as much crew error as possible. The position of the mainsail would make a differance, but we should be able to eliminate that at the dock by limiting the amount of sheet they can let out.)
The 2 frac. rigged boats will be able to check out their speed against the MH one. After a couple of runs, we will have one of the frac rigs raise thier keel, with the other one leaving it down and see what differance that makes. Does this sound like a good idea??

I'm pretty sure we can make this happen, and if we do I will let you know the results. Wish me luck on this, but I do have one owner ready to go.
AND, don't be in a rush for the results! The lake will frozen for another 6 weeks. :(
dave
Posts: 727
Joined: Fri Jan 02, 2004 10:39 pm
Location: Little Rock

Post by dave »

What, no arbitrarily, politically derived ratings? Heresy! Say it ain't so!

IMHO, what you are suggesting sounds like a good idea BUT.............. If all of the boats involved don't have very similar [and that means almost identical] bottoms, rudders and boards, [let alone sails and crew] your info won't mean much. It seems to me that you could run two or three downwind trials with the masthead rigged boat and then do the same thing ON THE SAME BOAT with the standard chute and get much more reliable data to do your calculations with. Then you also free yourself from two other boat's scheduling difficulties.
Tom Elsen
Site Admin
Posts: 419
Joined: Fri Dec 20, 2002 5:42 pm
Location: Minneapolis, MN & Chicago, IL

Some thoughts

Post by Tom Elsen »

Hi Allan
RE the frac vs the masthead rig test: I'd suggest that you run more tests on a shorter 1 nm course. Test the MH against the most similarly outfitted (sails / bottom etc) frac. Tell the drivers to keep lateral distance between boats as constant as possible. Also swap the crews. The crew swap will provide insurance against any 'sandbagging' on anybody's part.

RE the keel up vs keel down, that's a lot tougher and the results of the test are only marginally meaningful. (First, the 168 number is a 'standard configuration number', as you now know). Unless you're changing the specs, who cares? Second, in order for the test to be meaningful, both boats would need to be on their max VMG courses. That angle will differ for the board down boat vs the board up one. It could vary by as much as 30 degrees in very light air. So you've got a problem with the two boats sailing in different puffs / lulls.

You could sure make the argument that, in the absence of any significant hard data something is better than nothing. That's true. But I'd sure hate for other PHRF guys to misinterpret the results.

Thanks
Best wishes,
Tom
dave
Posts: 727
Joined: Fri Jan 02, 2004 10:39 pm
Location: Little Rock

Post by dave »

Everyone, that last sentence says it all. Doing these type of tests in only one wind/sea condition may do more harm than good. I believe that when properly administered by using race data taken over many months and under many conditions, most PHRF areas do a fairly good job at rating the different boats. That's why I included the GYA-PHRF link, which include how they handle this. They aren't perfect and have a few anomolies but they cover this ground pretty well.
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