Tim, You are certainly correct about VPPs and theoretical polars, as far as they go, but the high end of the sport went beyond that when they removed theoretical from the equation.
When Pyewacket shattered Merlin's the twenty year old TransPac record by a full day they did so using a computer program which stored polar performance data associated with sail configuration, rig loads, and sea state and informed the crew whenever they were dogging it. It was a 24/7 nag program, written by navigator Stan Honey which fed back what had been was faster before and by how much. My brother, a definite cruiser, would always be happy if the boat came somewhat near traditional hull speed. So for him using (and learning to achieve) the advanced hull speed would be a big stretch. I've been known to eek as much as an extra knot out of his boat just by trimming the sails. Certainly using the advanced formula makes sense for anyone needing a basic speed benchmark. If your serious about going racing it will help you understand how extra gear impacts your ultimate speed. Since VPPs are sail specific it doesn't make sense to invest in them until you're running mid pack with top race sails and need to know how to really let them fly. Phil Agur s/v Wing Tip (record 8.4 knots set by wife, Gina - no current) Commodore, Call Sign WCW3485 IC27/270A MMSI 366901790 www.catalina27.org Vessel Doc# 1039809 -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Monday, October 02, 2006 5:19 PM To: [email protected] Subject: RE: catalina27-talk: Hull Speed i think the whole idea of theoretical hull speeds has sorta gone the way of the...uh...square rigged top'sl. i mean, what difference does it make? Velocity Prediction Programs (VPP)s have made an attempt at rating boats for handicap racing and work reasonably well, but as far as I know the newest rating system that is trying to gain international acceptance, e.g., IRC, is based on a series of VPPs, averaged over a range of conditions and sea state probabilites (the IRC algorithims are a VERY closely guarded secret) [sorry about the spelling of "algorithims"]. People, on this list, can attest to the fact that a C27 will do 9-something knots off a wave front with a chute up in 25-30 knots of breeze. But a better representation of normal speeds assuming a clean, fair bottom and decent sails would be the polars for the boat. (I had them once and then they disappeared into the polarsphere) The bottom line is if you're racing One Design and the guy who started next to you is higher and faster, you're screwed. tf
