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 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 s/v Wing Tip Secretary, 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: 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
