How do you measure the waterline - SailNet Community
Reply
 
LinkBack Thread Tools
post #1 of 13 Old 07-26-2012 Thread Starter
Junior Member
 
Join Date: Apr 2011
Location: Chesapeake Bay
Posts: 19
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
How do you measure the waterline

How do you measure the waterline on a sailboat? I want to calculate the approximate best speed of my sailboat.
Do I measure the curve of the boat or just a straight line from the bow to the stern on the waterline?
boatingcruising is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 13 Old 07-26-2012
Senior Member
 
Tim R.'s Avatar
 
Join Date: Mar 2003
Location: Portland, Maine
Posts: 1,545
Thanks: 1
Thanked 27 Times in 26 Posts
Rep Power: 13
 
Re: How do you measure the waterline

Unless this is a custom one-off build you should be able to find the LWL easily online. What kind of boat specifically?

Tim R.
Out cruising
1997 Caliber 40LRC

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

-----------------------------------------------------
Tim R. is offline  
Quote Quick Reply Share with Facebook
post #3 of 13 Old 07-26-2012 Thread Starter
Junior Member
 
Join Date: Apr 2011
Location: Chesapeake Bay
Posts: 19
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Re: How do you measure the waterline

Hello Tim,
it is a Hunter 29' I am not sure of the model name
Domenic
boatingcruising is offline  
Quote Quick Reply Share with Facebook
post #4 of 13 Old 07-26-2012
Senior Member
 
Join Date: Oct 2009
Location: Virginia
Posts: 1,240
Thanks: 3
Thanked 25 Times in 25 Posts
Rep Power: 6
 
Re: How do you measure the waterline

Go to sailboatdata.com.
Theres a Hunter 290 listed with a 26.92 waterline.
One foot one way or the other is maybe one tenth of a knot so unless you are into serious racing, it really doesn't matter much.

Catalina 34
chuck53 is offline  
Quote Quick Reply Share with Facebook
post #5 of 13 Old 07-26-2012
Senior Cruiser
 
sea_hunter's Avatar
 
Join Date: Jul 2000
Posts: 512
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 16
 
Quote:
Originally Posted by boatingcruising:901643
How do you measure the waterline on a sailboat? I want to calculate the approximate best speed of my sailboat.
Do I measure the curve of the boat or just a straight line from the bow to the stern on the waterline?
Straight line through center at water line, overall inside toe rail bow to inside toe rail stern through center.
sea_hunter is offline  
Quote Quick Reply Share with Facebook
post #6 of 13 Old 07-26-2012 Thread Starter
Junior Member
 
Join Date: Apr 2011
Location: Chesapeake Bay
Posts: 19
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Re: How do you measure the waterline

Tks everyone
My goal is to simply have some idea of what the optimum performance of the sailboat would be so I can have a goal to shoot for. I am not into racing, at least not yet!

so if the waterline is 26.92 than the sq root is about 5.18 ( i used the calculator) so the optimum speed should be about 6.95 say 7kn. I hope I can learn to get at least 5.5 - 6 out of the boat.
boatingcruising is offline  
Quote Quick Reply Share with Facebook
post #7 of 13 Old 07-26-2012
Banned
 
Join Date: Apr 2011
Location: Southern California
Posts: 649
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Re: How do you measure the waterline

If you ever get to hull speed , please tell us the conditions
WDS123 is offline  
Quote Quick Reply Share with Facebook
post #8 of 13 Old 07-26-2012 Thread Starter
Junior Member
 
Join Date: Apr 2011
Location: Chesapeake Bay
Posts: 19
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Re: How do you measure the waterline

I am new to sailing but based on conversations with other sailors I get the feeling that reaching optimum hull speed is like getting the advertised gas millage in your car or obtaining the published speed of small aircraft at a set RPMs.

FORMUL: Optimum Hull Speed = Incredible Accomplishment
boatingcruising is offline  
Quote Quick Reply Share with Facebook
post #9 of 13 Old 07-27-2012
Senior Member
 
rbrasi's Avatar
 
Join Date: Mar 2011
Location: Henderson, NV
Posts: 573
Thanks: 5
Thanked 4 Times in 4 Posts
Rep Power: 5
 
Re: How do you measure the waterline

So, if at 25' LWL, my hull speed calculates to 6.7 Kt. What is the best measure? I currently use a Garmin GPS to get my speed readings, but that is speed over land. How does that translate? I routinely exceed 6.7 with current and a decent wind, according to my Garmin.

1968 Cal 2-30
Sandpiper 2
MDR
rbrasi is offline  
Quote Quick Reply Share with Facebook
post #10 of 13 Old 07-27-2012
Doesn't sail enough
 
zedboy's Avatar
 
Join Date: Jul 2010
Location: Eastern Med
Posts: 363
Thanks: 0
Thanked 18 Times in 18 Posts
Rep Power: 6
 
Quote:
Originally Posted by boatingcruising:901784
I get the feeling that reaching optimum hull speed is like getting the advertised gas millage in your car or obtaining the published speed of small aircraft at a set RPMs.
Apples to oranges - hull speed is an approximation of how a displacement hull will move. In flat water it shouldn't be hard to reach (I can even get close in my boat, which has horrific hydrodynamics - motor in well below w/l, ballast bolted to side of keel...

What builders/designers advertise is not hull speed, but polars - which ought to be based on their real world measurements (tho designers may post calculated polars on a design before it's built)

Ability to maintain hull soeed in varying conditions and over a sustained period of time is much trickier than hitting it for a few minutes 135 off the wind on a nice day
zedboy is offline  
Quote Quick Reply Share with Facebook
Reply

Tags
speed , waterline

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
Looking for C&C24 in Georgia to measure Madhatter23ct C & C 0 07-06-2012 09:45 PM
measure amp usage QuickMick Electrical Systems 17 03-31-2010 08:24 AM
how to measure sails pyrateparrothead General Discussion (sailing related) 7 02-22-2009 09:50 AM
How do I measure for shaft length? dhornsey Gear & Maintenance 3 06-20-2008 07:24 AM
Where to measure a winch at? wildcard Gear & Maintenance 9 07-16-2007 09:04 AM

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