How do I rate my N6.0 orig. W/spi on PHRF? I have scoured the internet and can't find anything. It seems that different areas of the country have formulated their own ratings for larger multi's acording to local racing, but i cant find anything on beachcats.

This the latest posted:

http://www.ussailing.org/portsmouth/pyindex.asp

Doug

Are you looking for DPN or PHRF?

The DPN for a N6.0na is 62.6.
The DPN modifier for a spinnaker is 0.96, so your DPN is now 62.6*0.96 = 60.1

To converto DPN to approximate PHRF, PHRF = 6 * DPN - 330

6*60.1-330 = 30.6 which gets you very close to what the US Sailing table says, here

http://www.ussailing.org/portsmouth/table_v.asp

Please be advised that conversion table you mentioned does not correct catamarans/multihulls. If I used that table my C 24 would move from PHRF 84 to PHRF 117 - the same rating as our J 29.

The conversion table was designed for mixing smaller monohulls with keelboats.

There are teams around the country working out some numbers so that cats and larger multihulls can participate in their local yacht club events.

The US Multihull Association Founding Committee is a few days away from becoming web - borne and active.

Please further note that the D-PN for the N 6.O original is 64.2, as found on the "Multihulls, Inactive" table.

It's been a long since I did this but I had the same problem. The US Sailing conversion is not applicable to multi's. If you try to sail with that rating and win, you will be protested and thrown out. There may be something about this in the Old Forum

I ended up using a method developed by the Corsair's. In simple terms it's hard to convert directly from PHRF to Portmouth because they work diffrently, PHRF is handicap based on distance sailed and Portmouth is handicap based on time sailed. However PHRF has PHRF(TOT) which works just like portmouth so there should be a simple relationship between them. (see http://www.nemasail.org/lussier.html). For data we used a boat with an accepted Portsmouth and PHRF, the F27 with a PHRF of 60 and a porstmouth of .72. I stiil have the spreadsheet which gives


INPUT-> 60 PHRF(TOD)
calculated 1.07 PHRF (TOT)
calculated 0.94 1/PHRF (TOT)


OUTPUT-> 0.719999646 Test Calculate Portsmouth# should be .72



INPUT-> 0.626 Portmouth #
OUTPUT-> -19.64 PHRF


I will look around and see if I can find the details.

Will there be a white paper comparing the PHRF like rating system comparing to the regional measurement based rating systems?

Please forgive the formatting error. This data represents over two years of racing point to point races and buoy races on Pensacola Bay out of PYC and PBYC.

Very primitive research/analysis - but it's a starting flag for mixing small yacht club fleets in order to encourage participation. Hell, experimenting with the ratings will only lead to evolution and provide drama.

Sample PHRF Wind Speed Adjustments for mixed fleet - drop mark/buoy racing* (PHRF Time on Time only)

Boat Design BN 2-3 BN 4 BN 5-6 BN 7+ (take the wife, dogs, and kids home)

J 29 123 120 117

Tripp 26 114 117 120

Elliot 770 111 114 120

Benetau 36.7 72 69 66

Melges 32 15 18 21

Melges 24 96 93 96

Corsair 24 87 84 78

F – 25 C -18 -21 -24

Corsair 28 R 21 18 15

Corsair S 750 27 33 36

Farrier 31 -21 -27 -30

NACRA 20 -48 -54 -45

Formula 18 -39 -45 -51

Formula 16 -30 -39 -36

Yep, Im not really looking for Portsmouth, I’m looking for PHRF.
It seems that the consensus is that there is no good conversion, and thus no PHRF for beachcats.
US Multihulls was trying to get their site running before the AC and hopefully will be able to put out PHRF tables. But it hasn’t happened yet.

Your table assumes that performance is linear in the range of B2-3 and I think that is a problem.

Your deltas seem reasonable for B3 (7- 10 knots or 7.5 to 12 mph) but way off for B2 (beach cat's to mono's.)

The modern high performance cats should be able to fly a hull at 8 or 9 knots (B3) upwind and down wind and sail to those ratings. However, at B2 the beach cats are stuck in the water and I doubt they can sail to the ratings you list and so one rating number for this range is off (one way or the other).

I suspect the B2-3 band was useful when the majority of boats were Hobie 16’s, 18’s etc and indeed their performance was much more linear in this range.

Did you consider wind ratings bands of 0-2... 3-4 and 5 to go home?

Resurrecting an old thread!
Has there been any more headway with respect to small multihull PHRF?

A bunch of us are sailing in the Governors Cup Regatta this weekend with the local YC and I made the mistake of reading the NOR. There will be a staggered start based on PHRF. The good thing is that the wind will build later in the day, giving the multis a great advantage, if we can provide some numbers.

USSAiling.org has DPN to PHRF conversion chart. It's not toally accurate, but it's what we've used in the past.

I'll check it out, Thanks for the info

AZCat and Mike,

That conversion chart was designed for mono to multi and has lost its relevance in this high performance market. I learned of this at a Multihull Council meeting in '08. It was designed by a NACRA 5.8 sailor who was Commodore of the Southern California YRA. We used it one year ('08) for the GYA Multihull Championship to fit a Weta into the trimaran division.

As a competitor I appealed, but Bob Curry was the crowd favorite, and Chris was given a PHRF number. I applied the same formula to prove my point and was ignored. If I were to use that formula/conversion, my C 24 would have the same rating as my J 29 :-) That dog will not hunt and needs to be scraped.

A few of us are tinkering with a performance system for handicapping the newer sport boats and trimarans which utilizes a wind bracketing system like the Portsmouth system for scoring tris against VX Ones etc; Bob Hodges is on call, and I need to get with Steve Green in San Fran to make headway. The Lake Multihull PHRF Comm has published an advisory for clubs NOT to combine multis and monos. Blatant segregation and hard on new HP boat owners to get involved.

If there is more widespread interest in this approach, get in touch with me via PM, and I will fill you in on our progress.

am I to understand PHRF correctly in that it varies by "region" and there appear to be different "scratch boats" in different PHRF areas?

I looked up my C24 rating (from 74 to 90) and it varies depending on which PHRF zone I'm using.


To be anywhere close to bridging the mono/multi conversion gap, would you have to practically sail all boats a nautical mile up and down in various wind/sea states (to get baseline information for future formula development)?

And how the heck would you develop formula(s) for semi- and full- foiling boats?

Have you submitted yourself to the Gulf Coast PHRF committee?

I think I hit the web page for a form, but not sure...?

Here?

http://wfphrf.org/?page_id=64

Not that one. Thanks for the linkey.

Since I don't know, and am too lazy to measure myself, can I submit just as a "stock" boat (no modifications) and would they know enough about multihulls to be able to crank that out for me?

What WE did to "correct" as much as possible the variance between PHRF and Portsmouth and still be able to use the PHRF handicap of distance on time, was to rate all boats first in Portsmouth (that means all the monohulls and cruisers). Then we converted all of the Portsmouth numbers to PHRF. This was the only way to have a somewhat fair reverse handicap race using a time on distance handicap, as Portsmouth is time on time.
Regarding accuracy, to put too much faith in any of the systems is a big mistake. PHRF has always been a dart board system with a heavy political mix of opinions of what a boat "should" rate. Hence the differences in various areas.
Portsmouth is only a little better as it did at one time actually crunch some numbers based on races. That said, you were still not taking into account the sailor's ability.

As an example, lets say a new boat comes out and races and Randy Smyth is sailing the boat. Another similar boat comes out and I sail that one. Then we come up with a handicap for the 2 boats. Guess which boat gets a golden rating and which one has a rating that "no one" can sail to? Picture that across the country. Not to mention the folks who push and whine for a better rating, if they are the "right" people, bingo they get an adjustment. etc.

Bottom line is all of us are desperate for a system that could rate all boats and offer a time on time or time on distance option for Club's and organizations to include "everyone" in their races. Let us know how your system develops.

All this said, remember that handicap racing is intended to be just for fun. None of it was ever consider to be really accurate. It is for Club racing and "ball park" comparisons.

Cheers,