portsmouth rating for my boat???
- Thread starter sand sailor
- Start date
- Status
Portsmouth rating?? Huh????
You must mean PHRF rating. Portsmouth ratings are usually reserved for racing dinghys (One Design) SANTANA 27 PHRF 201 That's from the PHRF New England site. Have you googled for information?
You must mean PHRF rating. Portsmouth ratings are usually reserved for racing dinghys (One Design) SANTANA 27 PHRF 201 That's from the PHRF New England site. Have you googled for information?
That's too weird
Less than two hours ago I was asking one of our local sailing gurus about the difference between PHRF and Portsmouth. I learned that Portsmouth is a time-on-time correction (expressed as a percentage) while PHRF rating (as most people know it) is a time-on-distance correction (expressed as seconds per mile). I was shown the exact same US Sailing web page for which R.W. posted a link. To complicate matters further, apparently there is also a way to convert PHRF to time-on-time, but it doesn't match the Portsmouth correction. Now all I need to figure out is how the H23 got listed under "Offshore".... Peter H23 "Raven"
Less than two hours ago I was asking one of our local sailing gurus about the difference between PHRF and Portsmouth. I learned that Portsmouth is a time-on-time correction (expressed as a percentage) while PHRF rating (as most people know it) is a time-on-distance correction (expressed as seconds per mile). I was shown the exact same US Sailing web page for which R.W. posted a link. To complicate matters further, apparently there is also a way to convert PHRF to time-on-time, but it doesn't match the Portsmouth correction. Now all I need to figure out is how the H23 got listed under "Offshore".... Peter H23 "Raven"
Yes
..it is a different handicap system than PHRF. As Peter has already said PHRF is a 'time on distance' rating whereas Portsmouth is a 'time on time' rating. I have the formula to convert but my Portsmouth book is at my office and I'll be there tomorrow and post it.
..it is a different handicap system than PHRF. As Peter has already said PHRF is a 'time on distance' rating whereas Portsmouth is a 'time on time' rating. I have the formula to convert but my Portsmouth book is at my office and I'll be there tomorrow and post it.
Handicap for SandSailor
PHRF and Portsmouth allow boats of different design and size to race against each other in the same event. The alternative is "one-design" racing, where everybody has the same design boat, e.g. Laser, Star, Catalina 22, etc. To be considered a one-design fleet, I think you need at least five boats of the same design. In mixed fleets, faster boats get a handicap for being faster. For example, the Hunter 23 has a PHRF rating of 234 while a Catalina 22 has a PHRF rating of 272. To beat the C22 in a race over one mile, the H23 has to finish at least 38 seconds (272-234) ahead. The margin changes proportionally with the distance, i.e., for PHRF to work, you need to know the length of the race. Under Portsmouth, each boat is assigning a number expressed as a percentage. Its elapsed time (ET) for the race is divided by this percentage (converted to a decimal fraction) to yield the corrected time (CT). The fastest corrected time wins. For example, Portsmouth number is 96.3 for the H23 and 97.1 for the C22. If the H23 finished in 60 minutes, its corrected time would be (60/0.963) which is 62.3053 minutes, or about 62 min. 19 sec. If the C22 finished 15 sec. after the H23 (ET=60.25 min) its CT would be (60.25/0.971) which is 62.0494 min, or about 62 min. 03 sec., which is good enough to beat the H23. The math is pretty simple and the race committee is freed from measuring the course. If you're going to be doing much racing you should know the numbers for your boat under both systems, as some race organizers like PHRF and some like Portsmouth. I hope that was helpful, considering I learned it earlier today. Peter H23 "Raven"
PHRF and Portsmouth allow boats of different design and size to race against each other in the same event. The alternative is "one-design" racing, where everybody has the same design boat, e.g. Laser, Star, Catalina 22, etc. To be considered a one-design fleet, I think you need at least five boats of the same design. In mixed fleets, faster boats get a handicap for being faster. For example, the Hunter 23 has a PHRF rating of 234 while a Catalina 22 has a PHRF rating of 272. To beat the C22 in a race over one mile, the H23 has to finish at least 38 seconds (272-234) ahead. The margin changes proportionally with the distance, i.e., for PHRF to work, you need to know the length of the race. Under Portsmouth, each boat is assigning a number expressed as a percentage. Its elapsed time (ET) for the race is divided by this percentage (converted to a decimal fraction) to yield the corrected time (CT). The fastest corrected time wins. For example, Portsmouth number is 96.3 for the H23 and 97.1 for the C22. If the H23 finished in 60 minutes, its corrected time would be (60/0.963) which is 62.3053 minutes, or about 62 min. 19 sec. If the C22 finished 15 sec. after the H23 (ET=60.25 min) its CT would be (60.25/0.971) which is 62.0494 min, or about 62 min. 03 sec., which is good enough to beat the H23. The math is pretty simple and the race committee is freed from measuring the course. If you're going to be doing much racing you should know the numbers for your boat under both systems, as some race organizers like PHRF and some like Portsmouth. I hope that was helpful, considering I learned it earlier today. Peter H23 "Raven"
Re: Portsmouth Yardsick
The Portsmouth Yardstick time on time rating also factors in the wind velocity based on Beaufort Number. Typically as the Beaufort Number(speed) goes up the rating number goes down. The Portsmouth Rating(D-PN)=(PHRF/6)+55 For example a boat rating 150 PHRF would have a D-PN=(150/6)+55 or 80. Each whole integer of D-PN is roughly equal to 6 seconds of PHRF. To use the Portsmouth Rating system for scoring any race: CT(corrected time)=ET/D-NP x 100 where ET is the elapsed time on course. The D-NP rating for a Hunter 23(wing keel) is 95.3 and a Santana 27 has a rating of 90.2
The Portsmouth Yardstick time on time rating also factors in the wind velocity based on Beaufort Number. Typically as the Beaufort Number(speed) goes up the rating number goes down. The Portsmouth Rating(D-PN)=(PHRF/6)+55 For example a boat rating 150 PHRF would have a D-PN=(150/6)+55 or 80. Each whole integer of D-PN is roughly equal to 6 seconds of PHRF. To use the Portsmouth Rating system for scoring any race: CT(corrected time)=ET/D-NP x 100 where ET is the elapsed time on course. The D-NP rating for a Hunter 23(wing keel) is 95.3 and a Santana 27 has a rating of 90.2
- Status