Join Date: Dec 2004
Location: Alameda, San Francisco Bay
Thanked 52 Times in 51 Posts
Rep Power: 11
The old saying goes: “Its not how low your rating number is. It’s how fast you sail against it”. I’m by no means an expert, but I have been to the PRHF committee a couple of times (C34 National Measurer). PHRF numbers are based on a formula calculated using basic dimensional data of the boat in question (I have it around here somewhere on excel, but I’m too lazy to look for it now). PHRF does not make adjustments for quality of equipment (carbon v. 20 year old Dacron) or condition of the boat (burnished bottom v. a “beard”). The formula breaks down when comparing multi’s to mono hulls and here in San Francisco, the multi’s race in their own divisions (heck, they even have their own racing association!). Generally, for the “cruiser-racer” production boat, the longer the water line (and subsequent increase in the sail plan) the lower the number. For example, out here the C34 rates144 and the slightly larger C36 is a 140. For comparison, a Areodyne 38 I used to crew on rated a 39 (but she was also a couple thousand pounds lighter than my Catalina), the Santa Cruz 50’s are -6, the Farr 40’s +2 and Westsail 32s are 225.
Hey, I found the formula!
R' = 610-8.36*(SA/Disp^.333)+0.0000511*(SA^2)-55*(P/(J+E)) -30.8*(LWL^.5)-602*(DR^2/SA)