Our fleet races use Portsmouth for handicapping the various boats. I've always thought that the Portsmouth time-on-time system made a lot more sense than the PHRF time-on-distance because the time-on-distance system gives slow boats the advantage in high wind days and fast boats the advantage if there are low winds (see http://www.rapidnet.com/~dt2000/portsmo ... ystem.html).
I've never seen a good explaination as to the merits of PHRF over Portsmouth. I wonder why everyone doesn't just use Portsmouth for handicapping in cases where there is a rating for all the boats in a race. Can anyone guide me to the answer?
Portsmouth vs PHRF
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baldbaby2000
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Schock Therapy
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In my area Portsmouth is used for dinghys and beach cats, and PHRF is used for racer/cruiser fleets. I have no idea whether there is even any rating data for the vast numbers of different keelboats that race. PHRF, on the other hand, has extensive data for rating just about any boat you can imagine, with the exception of the above mentioned dinghys and cats.
PHRF handicaps allow the race committee to score time-on-time or time-on-distance. 99% of the PHRF racing I have done over the last 15 years has been scored time-on-time. One good reason for this is that it makes the R/C job much more dificult if they have to worry about calculating the distance for each mark they set. Typically time/distance is only used on long-distance races where are the marks are permanent or geographical.
Time/Time has it's drawbacks also. It tends to favor the slower boats in variable conditions. For example, when a faster boat has worked hard to build up a lead that will allow them to "hold their time" on the slower boats, only to approach a mark that is in lighter wind, or even a hole. They can watch their lead disappear as the entire fleet compresses onto that light area.
No handicap system is perfect, but for the most part I think PHRF works quite well. There will always be exceptions such as custom or modified boats, as well as the possibility of political tampering on the local level. It is easy to get a rating, and there is room for ratings to evolve as more is learned about the performance of new designs.
Some of the fleets in my area are experimenting with IRC and ORC, and it will be interresting to see how they pan out. I'm not sure how well they will work for the casual or beginner racer since they require having the boat officially measured etc.
PHRF handicaps allow the race committee to score time-on-time or time-on-distance. 99% of the PHRF racing I have done over the last 15 years has been scored time-on-time. One good reason for this is that it makes the R/C job much more dificult if they have to worry about calculating the distance for each mark they set. Typically time/distance is only used on long-distance races where are the marks are permanent or geographical.
Time/Time has it's drawbacks also. It tends to favor the slower boats in variable conditions. For example, when a faster boat has worked hard to build up a lead that will allow them to "hold their time" on the slower boats, only to approach a mark that is in lighter wind, or even a hole. They can watch their lead disappear as the entire fleet compresses onto that light area.
No handicap system is perfect, but for the most part I think PHRF works quite well. There will always be exceptions such as custom or modified boats, as well as the possibility of political tampering on the local level. It is easy to get a rating, and there is room for ratings to evolve as more is learned about the performance of new designs.
Some of the fleets in my area are experimenting with IRC and ORC, and it will be interresting to see how they pan out. I'm not sure how well they will work for the casual or beginner racer since they require having the boat officially measured etc.
This is a tough one because I do not endorse TOT for where I live and the races I do. But TOT does have it's place with short races with small handicap spreads where current is non-existent and the wind is consistent across the race/course.
I have a mathematician/statistician crew member that has a weird fascination with handicapping systems and I let him have a crack at the 3 most common TOT methods. Any system (Port/PHRF/IRC) that uses TOT has a serious weakness in it's math. The TOT equations are only valid when there is enough wind to keep boats moving at (or close to) their hull speed. Any lighter and the system fails numerically, and if there is a change in current in the race it compounds it further. The systems are not designed to accommodate those variables. The TOT programs also fail when there are huge differences in handicapping among the fleet. Anything with more than 30 points of difference will start exacerbating the inherent problems in the equation, which ultimately penalize faster boats. The amount of error increases the bigger the handicap spread. Oh and don't get me started on the "variable" that R/C's can use to calculate the TOT, as the "variable" that they can use causes the errors to be further compounded due to the large handicap spreads in the boats racing.
Time on Distance is designed to disregard changing wind conditions and current. TOD is solely based on performance of a theoretical performance. That means if it goes light you still have the ability to hold handicaps. If the current sucks and you pick the correct side, you can hold your handicap against the boat. It's basic calculation inherently allows for changes in the environment without causing a failure in the validity of the system. It's weakest point then is the validity of the handicapping number.
I have a mathematician/statistician crew member that has a weird fascination with handicapping systems and I let him have a crack at the 3 most common TOT methods. Any system (Port/PHRF/IRC) that uses TOT has a serious weakness in it's math. The TOT equations are only valid when there is enough wind to keep boats moving at (or close to) their hull speed. Any lighter and the system fails numerically, and if there is a change in current in the race it compounds it further. The systems are not designed to accommodate those variables. The TOT programs also fail when there are huge differences in handicapping among the fleet. Anything with more than 30 points of difference will start exacerbating the inherent problems in the equation, which ultimately penalize faster boats. The amount of error increases the bigger the handicap spread. Oh and don't get me started on the "variable" that R/C's can use to calculate the TOT, as the "variable" that they can use causes the errors to be further compounded due to the large handicap spreads in the boats racing.
Time on Distance is designed to disregard changing wind conditions and current. TOD is solely based on performance of a theoretical performance. That means if it goes light you still have the ability to hold handicaps. If the current sucks and you pick the correct side, you can hold your handicap against the boat. It's basic calculation inherently allows for changes in the environment without causing a failure in the validity of the system. It's weakest point then is the validity of the handicapping number.