Kevin,
That's the traditional hull speed formula. Actually that's the hull speed formula for a "traditional" wooded hull. The 1.34 is derived from a particular type of hull construction. Everyone knows boat speed is impacted by boat displacement yet it's very common to accept a hull speed formula tat doesn't use displacement. Even my brothers Island Packet 38 wasn't heavy enough to warrant using the traditional hull speed formula. He was sure he had her flying until I came on board. I got another knot out of her because I had more accurate expectations. The advanced hull speed formula can be derived three of the chapters in The Nature of Boats: Insights and Esoterica for the Nautically Obsessed. Once you have the right formula a lot of things you know already start to fall into place. 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 Kevin Morton Sent: Sunday, August 10, 2008 11:44 AM To: [email protected] Subject: Re: catalina27-talk: Hull speed Technically speaking, hull speed is a function of the hull ONLY, it's nothing to do with engine or prop. The formula is to take the square root of the hull's length at waterline (in feet) and multiply this by 1.34. Thus a Catalina 27 with a LWL of 21.75 ft has a hull speed o 6.2 kts. Go to catalinaowners.com and there is some good information there. Also, may I suggest Yahoo's sailing online forum? It's more general in nature, but a WEALTH of qualiy information. Good luck! Kevin M. Morton S/V Serenity #1920 _/)_ --- On Sun, 8/10/08, Patrick R Ford <[EMAIL PROTECTED]> wrote: From: Patrick R Ford <[EMAIL PROTECTED]> Subject: catalina27-talk: Hull speed To: "IC27A" <[email protected]> Date: Sunday, August 10, 2008, 11:29 AM Hi Listers, I was told there is a way to calculate hull speed for a given boat. My C27 has a Petter 6 hp diesel--length at waterline is 21ft 9in--std keel-- displacement 6850lbs--LO 26ft 10in--beam 8ft 10in. Supposedly there is a formula to calculate --2800 rpm or 3000rpm with a 12 X 7 prop. ???? Anyone know how or where I can find it ??? Pat Ford Seabiscuit Port Washington, WI
