Appropriate mast bend? - SailNet Community
 4Likes
  • 2 Post By pdqaltair
  • 1 Post By Faster
  • 1 Post By tommays
 
LinkBack Thread Tools
post #1 of 8 Old 05-05-2014 Thread Starter
Senior Member
 
Join Date: Dec 2012
Location: Columbus, Ohio
Posts: 120
Thanks: 46
Thanked 3 Times in 3 Posts
Rep Power: 4
 
Appropriate mast bend?



Hi All,

I read through Seldon's mast tuning guide, as well as some other less formal guides when tuning my mast recently, and I got all the shrouds/stays tensioned correctly. this being my first time tuning a mast, however, I'm second guessing myself. The mast is in column. Is this amount of mast bend appropriate?

The boat is a Beneteau 361.

Any input is greatly appreciated.
bshock is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 8 Old 05-05-2014
ASA and PSIA Instructor
 
Join Date: Apr 2000
Posts: 3,680
Thanks: 10
Thanked 30 Times in 30 Posts
Rep Power: 17
 
Re: Appropriate mast bend?

Looks reasonable to me, what does the manual say about pre-bend, 8" or something like that? I assume the backstay was not tensioned for the picture?

Certified...in several regards...
sailingfool is offline  
Quote Quick Reply Share with Facebook
post #3 of 8 Old 05-05-2014
Senior Member
 
krisscross's Avatar
 
Join Date: Feb 2013
Location: NC
Posts: 2,847
Thanks: 29
Thanked 153 Times in 152 Posts
Rep Power: 4
 
Re: Appropriate mast bend?

Forgive my ignorance, but is mast rake (mast raked back just a bit) accomplishing basically the same thing?

Be kind, for everyone you meet is fighting a hard battle.
Plato
krisscross is offline  
Quote Quick Reply Share with Facebook
post #4 of 8 Old 05-05-2014
Senior Member
 
pdqaltair's Avatar
 
Join Date: Nov 2008
Location: Deale, MD
Posts: 2,816
Thanks: 1
Thanked 72 Times in 71 Posts
Rep Power: 8
 
Re: Appropriate mast bend?

Quote:
Originally Posted by krisscross View Post
Forgive my ignorance, but is mast rake (mast raked back just a bit) accomplishing basically the same thing?
No. When the mast bends the center of the luff moves forward, pulling sail cloth from the sail and making it flatter. An obvious corollary is that any sail to be used with a pre-bent or bendy mast is cut with this in mind.

Simplified, but the point is mast bend affects fullness, while rake primarily affects COE (also lift if extreme).
krisscross and christian.hess like this.

(when asked how he reached the starting holds on a difficult rock climbing problem that clearly favored taller climbers - he was perhaps 5'5")

"Well, I just climb up to them."

by Joe Brown, English rock climber




To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
pdqaltair is offline  
Quote Quick Reply Share with Facebook
The Following User Says Thank You to pdqaltair For This Useful Post:
Multihullgirl (05-05-2014)
post #5 of 8 Old 05-05-2014
Just another Moderator
 
Faster's Avatar
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 18,303
Thanks: 126
Thanked 458 Times in 435 Posts
Rep Power: 10
     
Re: Appropriate mast bend?

Quote:
Originally Posted by krisscross View Post
Forgive my ignorance, but is mast rake (mast raked back just a bit) accomplishing basically the same thing?
Mast rake will primarily affect your rig balance and the amount of weather helm you may or may not have since it moves your CE fore and aft. Mast bend generally is set to match the luff curve of your mainsail so that the draft position is optimal for the cut of the sail. More bend pulls material forward and 'flattens' the sail somewhat. A sail meant for significant prebend will have a very full shape set up a dead straight mast.
krisscross likes this.

Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
Faster is offline  
Quote Quick Reply Share with Facebook
post #6 of 8 Old 05-05-2014
Senior Member
 
tommays's Avatar
 
Join Date: Sep 2008
Posts: 4,304
Thanks: 1
Thanked 32 Times in 32 Posts
Rep Power: 8
 
Re: Appropriate mast bend?

The exact Pre-bend really depends on how the sail was cut as there are some pretty big difference's from one sailmaker to another

It is why there are 27 tuning guides for the J24 which vary from perfectly straight to really bent
christian.hess likes this.

1970 Cal 29 Sea Fever

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

1981 J24 Tangent 2930
Tommays
Northport NY


If a dirty bottom slows you down what do you think it does to your boat
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
tommays is offline  
Quote Quick Reply Share with Facebook
post #7 of 8 Old 05-06-2014 Thread Starter
Senior Member
 
Join Date: Dec 2012
Location: Columbus, Ohio
Posts: 120
Thanks: 46
Thanked 3 Times in 3 Posts
Rep Power: 4
 
Re: Appropriate mast bend?

Thanks guys for the insight.
bshock is offline  
Quote Quick Reply Share with Facebook
post #8 of 8 Old 05-06-2014
Senior Member
 
Join Date: Feb 2014
Posts: 632
Thanks: 1
Thanked 17 Times in 16 Posts
Rep Power: 3
 
Re: Appropriate mast bend?

Try the mast bend where you have it and see if you like how the sail sets. It looks like you have about 3~4" of bend or half a section. You're limited with a swept rig as to how much bend you can achieve.
Shockwave 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
Mast bend? AirborneSF C & C 8 04-09-2013 02:32 PM
mast bend Piratesoul Irwin 0 07-20-2008 06:20 AM
N30 mast bend RussLeighton Newport 2 06-06-2008 08:21 AM
Islander 28 mast bend remlap Islander 2 04-24-2008 11:39 PM
Mast Bend offline2004 Gear & Maintenance 7 02-17-2006 10:50 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