Sail to your PHRF #

[HERSH]

Just a little exercise I did with some recent results of a club race.

"Sail to your PHRF #"

According to PHRF;

J-92 PHRF = 111 Pearson 26 PHRF 222

J-92 in light air 3600/(111+600) = 5.06kts PHRF's predicted average speed for light air
P-26 in light air 3600/(222+600) = 4.37kts PHRF's predicted average speed for light air
kt = knots; ktm = nautical miles

J-92 covered 4.5ktm in 2 hrs & 7 minutes or 2.17 hrs
4.5/2.17 = averaging 2.125 kts

P-26 covered 4.5 ktm in 2 hrs & 21 minutes
4.5/2.35hrs averaging 1.914 kts

J-92 5.06 - 2.12 = 3.04 ( predicted speed - actual speed)
P-26 4.37 - 1.91 = 2.46 ( predicted speed - actual speed)

The Pearson 26 sailed closer to what PHRF predicted he should sail in light air then the J-92.

Therefor the P-26 wins !!!!!

Roy

Note:
For medium air replace 600 with 550
For heavy air replace 600 with 480

neither boat sailed even close to what PHRF predicts.

Bottom line -- you are racing against the clock, not the other boats .....


Hershey

Posts: 424
Joined: Mon Jul 08, 2013 9:48 pm
Location: http://chelseayacht.org
Boat Name: Hershey II
Sail Number: 427
Boat Type: Wing Keel Standard Rig

 

[BillL Capri 22]

4.5 ktm ... was that over water/actual distance or nominal around the buoys? (how did they actually sail the same distance to nearest 0.1 mile?)

Maybe get GPS tracks for the actual distance.

Of course this doesn't really affect you final conclusion: race the clock, not the other boat.

 

[shnool]

I'll add that in portsmouth rating system, that if your course is laid out as a triangle, and it's really just 3 tacks... that the highest handicap wins!

Because tactics are important, and point is part of your rating... And generally a faster boat will point higher than a slower one (think apparent wind). So if the RC screws up and lays out a course that does not have at least one leg dead upwind, and one leg dead downwind... then portsmouth (or most handicap ratings) fail.

In fact, I'll add that when the wind dies (and I mean dead, as in zero)... the way portsmouth ratings calculate the faster boats lose, and quickly... because the slow boats are expected to go slow (not zero but slow)... and the fast boats are expected to go faster (not zero ever)... so zero wind negates the ratings, so that slowest boat wins (again).

Is one reason why handicap racing stinks. I will tell you though that OD racing is a humbling experience... so maybe handicap racing ain't so bad.