This may be a stupid question.

**irwinsailor** · 01-05-2003, 09:42

Last friday night we went for a sail in 21 knot winds on lake Michigan. It was the fastest sail I have ever had. My question is : is 8.9 knots per hour in 21 knot winds in a 64000lb boat fast?

29cascadefixer · 01-05-2003, 19:21

My understanding ( such as it is ) is that the theroetical( sp ?)top speed of a displacement type hull is the square root of the waterline length. In your case I'm estimating around 7.5 - 8 miles per hour. Your speed was close to 9 knots which translates into about 11 miles per hour. Good on you ,Sir. I would say you had that Lady planing. Whooe.....

**GordMay** · 01-05-2003, 20:36

Hull Speed (Kts) = 1.34 x Square Root of Waterline Length (Ft).
If LWL = 55' Then Hull Speed = 9.9 Kts.
See:
http://sailingusa.info/cal__hull_speed.htm
And a great boat design informational at:
http://www.tedbrewer.com/yachtdesign.html
Ted Brewer Yacht Design

Regards,
Gord

**irwinsailor** · 02-05-2003, 22:42

So that old girl can move! I knew that hull speed was 9.9 knots for our boat, I just did not think I could come that close to it so soon.

01-05-2003, 09:42	#1
irwinsailor Moderator Site Helper Join Date: Feb 2003 Location: Macatawa Michigan Boat: Amanda Faye 61' Custom Irwin aftcockpit ketch Posts: 1,347 Images: 106	This may be a stupid question. Last friday night we went for a sail in 21 knot winds on lake Michigan. It was the fastest sail I have ever had. My question is : is 8.9 knots per hour in 21 knot winds in a 64000lb boat fast?

01-05-2003, 19:21	#2
29cascadefixer Registered User Join Date: Apr 2003 Location: Gladwin Mi. Posts: 145	Fast, I'd say so ! My understanding ( such as it is ) is that the theroetical( sp ?)top speed of a displacement type hull is the square root of the waterline length. In your case I'm estimating around 7.5 - 8 miles per hour. Your speed was close to 9 knots which translates into about 11 miles per hour. Good on you ,Sir. I would say you had that Lady planing. Whooe.....

01-05-2003, 20:36	#3
GordMay Administrator Site Administrator Join Date: Mar 2003 Location: Thunder Bay, Ontario - 48-29N x 89-20W Boat: C.L.O.D. (Cruiser Living On Dirt) Posts: 9,443 Images: 232	Hull Speed Hull Speed (Kts) = 1.34 x Square Root of Waterline Length (Ft). If LWL = 55' Then Hull Speed = 9.9 Kts. See: http://sailingusa.info/cal__hull_speed.htm And a great boat design informational at: http://www.tedbrewer.com/yachtdesign.html Ted Brewer Yacht Design Regards, Gord __________________ Gord May ~~_/)_~~ (Gord & Maggie - "Southbound") "If you didn't have time/$ to do it right in the first place, when will you get the time/$ to fix it?" Last edited by GordMay; 01-05-2003 at 22:09.

Thread Tools
Show Printable Version Email this Page
Display Modes	Rate This Thread
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode	Rate This Thread:

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Question about sailing routes from Japan to US	Tim	General Sailing Forum	3	05-03-2007 11:58
Question about Fuji 32?	Tim	Monohull Sailboats	10	29-11-2005 14:44
Question	Irish Ayes	General Sailing Forum	3	05-08-2004 11:56
Question about sailing routes from Japan to US	Tim	Other	0	28-04-2004 06:08
Wind vanes on catamarans??	svstrider	Multihull Sailboats	5	13-07-2003 17:02

02-05-2003, 22:42	#4
irwinsailor Moderator Site Helper Join Date: Feb 2003 Location: Macatawa Michigan Boat: Amanda Faye 61' Custom Irwin aftcockpit ketch Posts: 1,347 Images: 106	So that old girl can move! I knew that hull speed was 9.9 knots for our boat, I just did not think I could come that close to it so soon.