GZ curve - SailNet Community
Reply
 
LinkBack Thread Tools
post #1 of 19 Old 06-18-2007 Thread Starter
traveller
 
Join Date: Jan 2006
Location: CHILE
Posts: 27
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
GZ curve

Hi every body.
Does any one knows were can I get a comparison chart on GZ curve for different types and models of sailing boats ( if any).
Thanks in advance
genesis-uno is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 19 Old 06-18-2007
Jersey Member
 
STARWINDY's Avatar
 
Join Date: Apr 2007
Location: Bayville, New Jersey
Posts: 81
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
 
try boatdesign.net, there might be some help in there.

Good luck.
STARWINDY is offline  
Quote Quick Reply Share with Facebook
post #3 of 19 Old 06-18-2007 Thread Starter
traveller
 
Join Date: Jan 2006
Location: CHILE
Posts: 27
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Thanks Starwindy for your info, it was the right place. By
genesis-uno is offline  
Quote Quick Reply Share with Facebook
post #4 of 19 Old 06-18-2007
.
 
Join Date: Nov 2006
Posts: 10,851
Thanks: 0
Thanked 5 Times in 2 Posts
Rep Power: 13
         
Go here, this is all you need
Giulietta is offline  
Quote Quick Reply Share with Facebook
post #5 of 19 Old 06-19-2007 Thread Starter
traveller
 
Join Date: Jan 2006
Location: CHILE
Posts: 27
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Giuleta,
Thanks for your tip. Now, I did a comparison between two boats regarding Capsize ratio: one is 1.92 and the other is 1.99, Can you tell me how do I have to interpret this ratio?, the same in the Motion comfort: one is 25.77 and the other is 23.65 an the last, Hull speed one is 8.1 and the other is 7.77. I presume that this one is the average speed that the boat can give, is that right?.
Thanks in advance for you info.
genesis-uno is offline  
Quote Quick Reply Share with Facebook
post #6 of 19 Old 06-19-2007
.
 
Join Date: Nov 2006
Posts: 10,851
Thanks: 0
Thanked 5 Times in 2 Posts
Rep Power: 13
         
Genesis, if you click in the white block with your right mouse button, where it says the things you want to know, you can read in the explanation of that.

Hull speed is the max speed a hull (displacement hull only), (not applicable to statre of the art planing hulls), can achieve, and its calculated based on lenght at the water line. The longer the LWL the faster that boat can go.

The formula is HS = (LWL) Power 1/2 X 1.34

It only works for boats that do not plane in the water.

Basically when a boat moves in the water it creates a wave that restriscts the increase of its speed. It will be trapeed in it own water displaced water.

When moving, a boat will create a wave in the bow and another wave in the rear, in the stern. When the boat gets near its hull speed the two waves will combine to make only one wave.

What happens is that the boat will be unable to go "over" its own wave, no matter how hard it is pushed, the wave just gets bigger and he can't go any faster.

That is when fine very good looking excellent nice sailboats like yours trully come to play...these very high effecient modern good looking hulls, called planing hulls, due to their flat appearance and low drag, are able to start "surfing" over the surface of the water, and once they do that, they start planing over the wave, then, no longer under the influence of the wave, they can accelerate further.....and fly as fast as the wind!!

Was that clear?

The photo bellow shows a boat that is going so fast the waves are really big. At this point, the Spi was hoisted and the boat starts to accelerate. The boat at this stage is not surfing yet. here is bellow 9 knots.



Once it starts surfing, the wave effect no longer apply all you have is a smooth wake, here it is going at around 17 knots.



I'll see if I have more

Last edited by Giulietta; 06-19-2007 at 02:39 PM.
Giulietta is offline  
Quote Quick Reply Share with Facebook
post #7 of 19 Old 06-19-2007
can't re member
 
Join Date: Aug 2006
Posts: 318
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
 
Quote:
Originally Posted by Giulietta
Genesis, if you click in the white block with your right mouse button, where it says the things you want to know, you can read in the explanation of that.

Hull speed is the max speed a hull (displacement hull only), (not applicable to statre of the art planing hulls), can achieve, and its calculated based on lenght at the water line. The longer the LWL the faster that boat can go.

The formula is HS = (LWL) Power 1/2 X 1.34

It only works for boats that do not plane in the water.

Basically when a boat moves in the water it creates a wave that restriscts the increase of its speed. It will be trapeed in it own water displaced water.

When moving, a boat will create a wave in the bow and another wave in the rear, in the stern. When the boat gets near its hull speed the two waves will combine to make only one wave.

What happens is that the boat will be unable to go "over" its own wave, no matter how hard it is pushed, the wave just gets bigger and he can't go any faster.

That is when fine very good looking excellent nice sailboats like yours trully come to play...these very high effecient modern good looking hulls, called planing hulls, due to their flat appearance and low drag, are able to start "surfing" over the surface of the water, and once they do that, they start planing over the wave, then, no longer under the influence of the wave, they can accelerate further.....and fly as fast as the wind!!

Was that clear?
Mostly clear...at what point does the boom break?
yotphix is offline  
Quote Quick Reply Share with Facebook
post #8 of 19 Old 06-19-2007 Thread Starter
traveller
 
Join Date: Jan 2006
Location: CHILE
Posts: 27
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Giulieta:Thanks very much for your VERY PROFESSIONAL AND CLEAR EXPLANATION.You answered all my doubts. Any other grafic information is very welcome.
Regards
genesis-uno is offline  
Quote Quick Reply Share with Facebook
post #9 of 19 Old 06-19-2007
.
 
Join Date: Nov 2006
Posts: 10,851
Thanks: 0
Thanked 5 Times in 2 Posts
Rep Power: 13
         
what do you want to see?? A very very very good sailor??? or an ugly Exmoderator??

Here's a side view of a very pretty boat I saw once.

The first one, before she rides the wave...the second one riding the wave...look at the difference..the bow lifts off the water when surfing, and the difference in bow wake and water thrown out.





OK here are a few photos of a planing hull, these are from a very very very pretty ellegant good looking boat I found on the net. (The guy that owns is for sure a very very very good looking handsome extremely good sailor, also.)








CAN SOMEONE POST A PHOTO OF A DISPLACEMENT HULL?? PLEASE? i ONLY HAVE PLANING HULL PHOTOS.

Last edited by Giulietta; 06-19-2007 at 04:11 PM.
Giulietta is offline  
Quote Quick Reply Share with Facebook
post #10 of 19 Old 06-19-2007
Senior Member
 
tomaz_423's Avatar
 
Join Date: Feb 2006
Location: Slovenia
Posts: 415
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 10
 
Hmm. Looks like a nice boat, but she have kind of fat ass.

P.S.
The only planning sailboat I ever had was a laser (and even that was my brother's). I can only try to imagine the thrill, excitement and joy of planing with a 40 footer...


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Beneteau Oceanis 473

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

finished cruising after two years.
tomaz_423 is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
J-40 for Long Distance Cruising ? ddimaui Boat Review and Purchase Forum 66 12-30-2008 06:54 PM
How heavy is too heavy II ? PCP General Discussion (sailing related) 14 09-21-2007 09:48 PM
C36 Dual Anchor Set Up MarkWood Catalina 24 06-14-2007 09:33 PM
Help us shorten our learning curve... What was the dumbest/worst mistake you've made? Fearless General Discussion (sailing related) 153 03-20-2007 04:54 PM
Learning curve PBzeer General Discussion (sailing related) 23 11-30-2006 11:32 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome