PHRF conflicts with LWL -

RussC

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Sep 11, 2015
1,578
Merit 22- Oregon lakes
Help me out here. What else contributes to a low PHRF other that LWL? there are quite a few boats out there that claim sub 200 PHRF that are under 25'. Pointing ability obviously would be a factor here, but can that really be the whole story?? seems like a worthy discussion to have.
 
May 25, 2012
4,333
john alden caravelle 42 sturgeon bay, wis
sq. ft of sail area on a given boat ..................................
 
May 17, 2004
5,025
Beneteau Oceanis 37 Havre de Grace
PHRF is, as its name suggests, is performance based. There's no formula to determine a rating based on measurements. In general a longer LWL will be a big factor, but planing hulls, for example, will perform very well even with small lengths. Things like prevailing conditions in a region also play into the rating as a lighter boat might be favored in a light wind area.
 
Mar 29, 2011
169
Beneteau 361 Charlotte,Vt
PHrF ratings are reached based on a based rating and then adjusted for individual boats based on the set up of that boat. US Sail publishes the base ratings. The individual rates are arrived locally. There is normally RHRF rating board for your area. So things that will effect a rating are, spinnakers, modification to the boat, and so on. The slower the boat the higher the rating. Most racers like to have a higher rating.
 
Aug 3, 2012
2,542
Performance Cruising Telstar 28 302 Watkins Glen
Weight is going to effect the rating too. Sail area, hull shape, sail plan, ballast plan, among others, will effect speed with similar sized hulls. Also, number of hulls... I have a 28' trimaran that will do 15-18 kts! Not many 28' boats will sail that fast! On the other hand, a 27' Corsair will whip my A$$... :kick:
ok. That's not A$$... but it still hurts!
I guess the point of PHRF is sailing YOUR boat to its potential. However, overall speed is nice too!
 
Jan 11, 2014
11,319
Sabre 362 113 Fair Haven, NY
PHRF is a good idea gone bad.

Ostensibly, the goal of a PHRF rating is to make all boats a one design. But, even in one design not all boats are equal.

I've been critical of PHRF and ratings and think that PHRF is hurting our sport because it focuses on boat performance not crew performance. Imagine if golf handicaps were based on the brand of club used. That's what PHRF does.

If you are interested in my thoughts and some ideas about an alternative read the posts here: Racing
 
Aug 3, 2012
2,542
Performance Cruising Telstar 28 302 Watkins Glen
I think PHRF tries to equalize boats specifically so that crew performance becomes the deciding factor.
 
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Joe

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Jun 1, 2004
7,999
Catalina 27 Mission Bay, San Diego
The PHRF rating is a "handicap". Although you can speculate on a given boat's rating by using lwl and other design features. The final rating is assigned as a result analyzing actual race performance data......adjustments are made for additional modifications and conditions. (Think of a golfer's scorecard being compared to the course's rating before a final handicap is determined. Or one golfer's handicap is compared to his opponent to determine which holes give the higher handicap an advantage)

Here is an example of how adjustments to the base rating are considered in the Chesapeake bay region. http://www.phrfchesbay.org/docs/Modifications.pdf
 
Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
Or, @Jackdaw , the colour of the cloth. Black must be faster because, as they say, chrome won't get you home.
 
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Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Long LWL only helps once you hit hull speed. Until then it's just extra paint to drag around in the water ( wetted surface).

No single factor rules.

I've been on 35 Footers that have rated 75 and 190

I've also been on 28 footers that have rated 75 and 190

Go figure.
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Or, @Jackdaw , the colour of the cloth. Black must be faster because, as they say, chrome won't get you home.
Oh yea. Looking fast will adversely effect your rating. The trick is it have it ACTUALLY effect your rating more than the looks do. ;-)
 

walt

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Jun 1, 2007
3,511
Macgregor 26S Hobie TI Ridgway Colorado
Sort of interesting (and hopefully I did not make any mistakes here)..

This chart can compare two boats PRHF ratings and give you the seconds per minute handicap.
http://www.gtyc.org/Resources/Documents/Racing/2013 GTYC TOT calculator.pdf

The example at the bottom of the page compares a boat PRHF 90 to 120 and one boat gets a handicap of 2.8 seconds per minute.

A minute is 60 seconds so 2.8 seconds means the two boats speed differ by around 4.6%.

Using the same table for 204 vs 189, the handicap is 1.2 seconds which only around 2%.

2% difference is huge if you are racing.. But if you are just trying to get somewhere.. 2% doesn't matter much.

Regarding LWL, keep in mind that you need some power to get to hull speed and generally this requires at least a little bit of wind. But racing is in all winds and Im sure someone will want to argue this but when boats speeds are way below THS, the importance of length is reduced.
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Actually, light weight is the biggest factor for any given length.
 
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Aug 1, 2011
3,972
Catalina 270 255 Wabamun. Welcome to the marina
And the ability to stay at an optimal trim, and recover to one from a change in direction.
Our 26c used to run circles around the keel boats till they figured out we were intentionally drawing them into tacking duels. We could accelerate far faster.
 

RussC

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Sep 11, 2015
1,578
Merit 22- Oregon lakes
Long LWL only helps once you hit hull speed. Until then it's just extra paint to drag around in the water ( wetted surface).
Awwww. this was the obvious point I was missing :redface:. sailboats seldom race in winds that provide hull speed at all times, so light wind performance becomes king. great food for thought. thanks.
 
Jan 4, 2010
1,037
Farr 30 San Francisco
This is a formula that purports to kick out PHRF ratings. It isn't official but gives you an idea of what the weight of various speed factors could be. I think in the end PHRF is pure observation and as they say it is a terrible system except for all the others. Jim Antrim had a funny take on PHRF rummage around on his web site it might still be there. Basic idea was to share your boat with a terrible sailor. He collects all the last places you collect the silver.

https://www.well.com/~pk/YRAphrf-sf.html
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
This is a formula that purports to kick out PHRF ratings. It isn't official but gives you an idea of what the weight of various speed factors could be. I think in the end PHRF is pure observation and as they say it is a terrible system except for all the others. Jim Antrim had a funny take on PHRF rummage around on his web site it might still be there. Basic idea was to share your boat with a terrible sailor. He collects all the last places you collect the silver.

https://www.well.com/~pk/YRAphrf-sf.html

That's 100% not what that is. It's a regression that attempts to fit all existing rating into a formula. It makes absolutely no claim to give me an actual ratings. Some mathematician did it as a joke. It's just simply distributes ratings across the mean.
 
Jan 1, 2006
7,039
Slickcraft 26 Sailfish
PHRF takes a lot of criticism but it is one of only a few ways to rate dis-similar boats. Formula based rating are great for boats of similar length and sailing characteristics but to rate J-35C against C&C 27 MK V, PHRF works pretty well. At least well enough to keep those boats coming out for races they think they can win. Or consider our spinnaker class in which a Ranger 26, or a Catalina 27 can best one or several of the J-80's. I probably should spend more time on this post but I gotta go. PHRF is PHRF. Get used to it.
 
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