Art,
The whole point was to supply the weight sensitive hull speed formula not to supply another arbitrary number. Of course no one should be using an assumed factory weight but get a real weight. BTW 6850 yields 6.52 knots. Phil Agur <http://www.catalina27.org/public_pages/profile270.htm> s/v Wing Tip Secretary, Call Sign WCW3485 IC27/270A MMSI 366901790 <http://www.catalina27.org> www.catalina27.org Vessel Doc# 1039809 -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of HERRICK Sent: Tuesday, August 12, 2008 6:36 AM To: [email protected] Subject: Re: catalina27-talk: Hull speed What kind of boat do you have that weighs only 5700 lb? My '84 displaces 6850 lb, w/ M-18 Diesel. I heard that the disp. grew over the years, but 1150 lb. is a big jump! Art Herrick #5468 Sea Change ----- Original Message ----- From: Phil A <mailto:[EMAIL PROTECTED]> To: [email protected] Sent: Monday, August 11, 2008 3:53 PM Subject: RE: catalina27-talk: Hull speed That's consistent with my wife's record of 8.4 knots on Wing Tip. Broad reach in 25 -30 knots with no sea. Of course that's nothing compared to my 85 when the CHP just shook his head. Instead of using 1.34 a C27 uses a factor more like 1.5 resulting in a 6.92 knot hull speed. Disp. = 5700 Lbs. LWL= 21.75 Ft. Dave Gerr - The Nature of Boats D/L = 247 Eq #1: D/L=(weight/2240)/(0.01 * LWL)^3 S/L = 1.49 Eq#2: S/L = 8.26/(D/L)^0.311 Adv. Hull Speed= 6.94 Knots Eq#3: Hullspeed = S/L * LWL^0.5 Traditional HS= 6.25 Knots Assumes S/L= 1.34 And of course TF may have been dogging it since square root of 34.5 (LWL) x 1.5 = 8.81 kn. If the J Boat hull was higher tech than a typical Catalina then reduced weight could force it higher. I know I may be stretching my credibility here but I didn't write the book. Remember Pyewacket didn't shatter Merlin's 12 year Tran Pac record until they had a computerized Polar performance program nagging the crew when they were slow. And then they shaved off a full day. A full day! Just knowing you're slow is a major part of the battle to win. Never settle for traditional hull speed again unless you're sailing a traditional construction boat. Phil Agur <http://www.catalina27.org/public_pages/profile270.htm> s/v Wing Tip Secretary, Call Sign WCW3485 IC27/270A MMSI 366901790 <http://www.catalina27.org> www.catalina27.org Vessel Doc# 1039809 -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Sunday, August 10, 2008 6:10 PM To: [email protected] Subject: RE: catalina27-talk: Hull speed or slightly above hull speed... was on a J122 today and (just very slightly cracked off) saw 8.4 knots, upwind in a 15 kn breeze. hull speed plus tf pix and it happened square root of 34.5 (LWL) x 1.34 = 7.88 kn > > Weight maters but I'll have to hunt for the advanced hull speed formula. > > Phil Agur s/v Wing Tip > Secretary, Call Sign WCW3485 > IC27/270A MMSI 366901790 > www.catalina27.org Vessel Doc# 1039809
