View PHRF-NS Handicapping brochure
What is PHRF?
PHRF is a standard keelboat handicapping system used throughout North America. The initials stand for Performance Handicap Racing Fleet which sums up the system nicely. In Nova Scotia our former Performance Handicap system was known as ASPN (Atlantic Speed Potential Number) and works in the same manner as PHRF. Under both systems vessels race in open regattas and the handicaps are assigned and maintained based on observed performance on the race course. This process takes into account local variations in conditions from fleet to fleet across North America and accounts for regional discrepancies from one area to the next.
Under the ASPN system the assigned handicap was actually a Time Correction Factor (TCF) expressed as a percentage. For Time on Time racing the actual or elapsed time of a vessel is multiplied by the TCF to calculate the corrected time. This is the same process using PHRF when racing in a Time on Time format.
Where PHRF differs from ASPN is in what the handicap numbers represent. Under ASPN the handicap is the Time Correction Factor. However in the PHRF system the handicap is the number of seconds a vessel will sail one nautical mile compared to a mythical scratch boat. Accordingly if the scratch boat would sail a circular 1 mile course in X seconds then a boat that would sail the same course 182 seconds slower would have a PHRF handicap of 182.
How do we race Time on Time PHRF?
PHRF was designed as a handicap to be used over triangular courses of pre measured distances. This is known as Time on Distance racing. In Nova Scotia and in other areas a Time on Time variation has been adopted. A formula is used to calculate a Time Correction factor (TCF) from the PHRF handicap. The formula utilizes A and B factors which can be adjusted for wind directions and course layout. NSYA uses A=695 and B=525. The formula is as follows:
TCF = A / (B + PHRF)
The TCF for each vessel in the Sail Nova Scotia fleet is calculated and displayed at the bottom of the vessel details page in our handicap database.
To calculate corrected times with PHRF Time on Time racing we multiply the boat’s Actual time by the TCF in exactly the same manner as was done using ASPN.
What Software do I use to run a race?
As PHRF is a standard handicapping system there are several software products available that will work. The most widely available product is called SAILWAVE and can be downloaded free of charge from www.sailwave.com This software is already in use at a number of clubs in Nova Scotia and PEI and around the world. All that is required in setup is to enter Actual Time, Handicap and the A and B factors in order for Sailwave to calculate race results. Winregatta may also be used by entering the TCF as a percentage in place of the ASPN handicap.
Another alternative is to use software such as Excl to calculate results. Using the formula above and A=695 and B=525 it is relatively simple to create a spreadsheet to calculate corrected times and scoring based on the PHRF rating and actual elapsed time. NSYA has available a spreadsheet that has been formatted to do this if anyone wishes to use Excel.
How were PHRF-NS ratings obtained and why are they different than other PHRF areas?
This is a commonly asked question that deserves a thoughtful response.
Prior to August 2008 a PHRF number was displayed on the Sail Nova Scotia website for each boat. It must be noted that this was an approximate number that used a simple conversion formula to calculate a PHRF like number. What must also be noted is that while this was close for boats in an ASPN 100 – 115 range it became further distorted as boats became faster. The end result was that Sail Nova Scotia appeared to rate boats in the 110ASPN range faster than other PHRF areas and boats in the very fast end of our fleet slower than other areas. This was largely due to the built in A & B factors that were included in our ASPN handicapping system. At this point we should also remember that at the time the ASPN system was created a very fast boat was ASPN 120 and a typical boat was ASPN 100 – 110. For this and other reasons the old conversion formula and published PHRF like numbers were removed from NSYA web site in August 2008.
In the Fall of 2008 NSYA (now Sail Nova Scotia) set new PHRF base handicaps for our fleet. The prime requirement when setting these handicaps was to maintain the characteristic of the NSYA fleet rather than using PHRF numbers set in other areas. In very simple terms this maintains the speed relationships between boats in NSYA as existed at the time in our ASPN system. The process adopted by NSYA has been named the Reference Method and has preserved to the greatest extent possible the many years of racing history established in Nova Scotia.
The reference method utilized is a simple concept. A number of very standard boats (ex. J35) at approx 5 ASPN point intervals were selected and the ASPN base rating pegged at an average of 5 very strong PHRF areas with the same standard boats. The regional variations in Nova Scotia were preserved by maintaining the ASPN speed relationship of every boat in the Sail Nova Scotia fleet to these standard boats to determine the PHRF number. Utilizing this method boat A is still faster or slower than boat B if it was in ASPN. Our PHRF base handicaps are in line with other PHRF areas while maintaining the speed relationships that have already been established in Nova Scotia under the ASPN system.
How can I compare PHRF handicaps to ASPN handicaps?
Formerly we could compare roughly an ASPN number to PHRF by using the following formula: ASPN=63000/(PHRF + 400). This was not an exact conversion especially as boats become faster. When ASPN came into being a Tanzer 22 at ASPN 100 was a typical boat and a fast boat was 120 ASPN. At this time the Tanzer 22 is no longer our median boat as it is 112ASPN which would me a C&C30 or a Kirby 25.
In the ASPN system a rating of 100 would have an increment of 1 ASPN point = 6 PHRF (sec/mile). As boats get faster the relation between ASPN and PHRF changes roughly as follows. ASPN 103 – 122 have 1 ASPN = 5 sec/mile. ASPN 123 – 149 have 1 ASPN = 4 sec/mile. ASPN 150+ has 1 ASPN = 3 sec/mile
This skewing as resulted in problems with boats being translated to ASPN from PHRF and vice versa. This resulted in the formula shown above not representing accurately how boats in Nova Scotia compared in speed to other areas – with very fast boats (150ASPN + ) being slower in NS than other areas and average and slower boats being faster than many other areas. While it does not matter when racing within Nova Scotia (we rate boats relative to others in our area) it does make a difference when our boats travel to other areas or new boats are brought into our system. This makes comparisons between ASPN and other PHRF areas less simple than it should be and can lead to misinterpretation.
How are Adjustments applied with PHRF-NS and why do they differ from ASPN?
The typical adjustment in PHRF systems is by increments of 6 sec/mile with fine adjustments at 3 sec/mile. Under ASPN we used 1 ASPN point which roughly equates to 6 sec/mile at the low end up to 3 sec/mile at the fast end of the fleet. There has been a problem where a 1 point ASPN adjustment to a very fast boat is a different penalty to the same 1 point adjustment to a boat at approximately 100 ASPN.
With NSYA adoption of PHRF handicapping the base ratings of one boat to another have retained the relationships established using ASPN. However standard 6 sec/mile adjustment increments this will often result in minor changes in boats that have large adjustments when compared to other boats. As an example a Tanzer 26 rating 105ASPN base rating is 207PHRF while a Thunderbird at 106ASPN has a base rating of 202PHRF. If the Thunderbird had an undersized headsail under ASPN it would be adjusted -1 to 105 ASPN – the same as the Tanzer 26. Using our PHRF 6 sec/mile adjustment the Thunderbird will now be 208 PHRF or 1 sec/mile slower than the Tanzer. This difference is equivalent to approx 0.2 ASPN points and is neligible.