Fiberglass question - SailNet Community
 1Likes
  • 1 Post By Gary M
 
LinkBack Thread Tools
post #1 of 7 Old 04-02-2012 Thread Starter
Battered and Bruised
 
Silvio's Avatar
 
Join Date: Nov 2010
Posts: 490
Thanks: 0
Thanked 7 Times in 4 Posts
Rep Power: 5
 
Fiberglass question

Quick question to everyone with some knowledge of fiberglassing in an old through hull. I was reading the latest issue of one of my favorite sailing magazines which happened to have a very good write up of glassing in an unused, or three, through hulls. I have read else where and it was the case in this article, that the hull should be ground out in a feathered fashion creating a concave depression that has roughly a 12:1 slope to the edges.Then consecutively increasing (or decreasing depending on point of view) discs of glass matting should be cut totaling 10-12 layers in total.

Here is the part that confused me. The article has the circles of matting being laid in with the largest diameter disc first working out to the smallest. This seems backward to me. Isn't the point of the different sized discs to get them to overlap their edges as they build up? The article seems counter intuitive, I would think the smallest diameter disc would go against the through hull opening and then the next larger, next larger, and so on.

I know this was a long winded question that I could probably find a convincing answer to if I look long enough, but I know that there are several experienced glass repair folks on Sailnet that can probably set me straight without too much effort.

Thanks,
Silvio

SV S.S.R.I
It's my happy pill
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Silvio is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 7 Old 04-02-2012
Senior Member
 
Gary M's Avatar
 
Join Date: May 2006
Location: Sarnia ON
Posts: 693
Thanks: 3
Thanked 5 Times in 5 Posts
Rep Power: 10
 
Re: Fiberglass question

The article is correct but what you say is intuitive, in fact the first through hull that I glassed in was done as you say. Some one here I believe explained the correct way.

The first layer of glass should cover the maximum area as it is the most important one and really needs to bond well.

Start with the full sized disc and gradually get smaller until the tapered depression if fairly flush then fair it.
wdwright1967 likes this.
Gary M is offline  
Quote Quick Reply Share with Facebook
post #3 of 7 Old 04-02-2012
Senior Member
 
CaptainForce's Avatar
 
Join Date: Jan 2006
Location: living aboard since 1972
Posts: 1,715
Thanks: 0
Thanked 12 Times in 12 Posts
Rep Power: 10
 
Re: Fiberglass question

Silvio, Though I agree with Gary M and his understanding of the proper procedure, Thanks for the question. I, too, always think that the reasonable method would be to have the greatest number of layers bonded to the original surface, but then I remember that my reasoning does not match the instructions. Take care and joy, Aythya crew
CaptainForce is offline  
Quote Quick Reply Share with Facebook
post #4 of 7 Old 04-02-2012
Senior Member
 
mitiempo's Avatar
 
Join Date: Sep 2008
Location: Victoria B.C. Canada
Posts: 7,487
Thanks: 0
Thanked 94 Times in 85 Posts
Rep Power: 8
   
Re: Fiberglass question

When you place the largest piece first each subsequent layer bonds very well to it. I do it that way and the other reason is that any sanding will not abrade the largest piece.
I wouldn't use only mat - it has little strength. I like biaxial 1708 which is stitched roving with mat on one side and epoxy compatible. Usually only 2 or 3 layers are needed. I glass the inside as well.
After grinding the taper outside tape something over the inside of the hole and fill the hole from outside with thickened epoxy flush with the ground edge. When the inside is glassed with one layer only a bit of sanding is required and there is no reason to fair if it will be hidden.

Brian
Living aboard in Victoria Harbour

Last edited by mitiempo; 04-02-2012 at 09:21 PM.
mitiempo is offline  
Quote Quick Reply Share with Facebook
post #5 of 7 Old 04-02-2012
Senior Member
 
davidpm's Avatar
 
Join Date: Oct 2007
Location: Madison
Posts: 3,953
Thanks: 235
Thanked 61 Times in 52 Posts
Rep Power: 8
 
Re: Fiberglass question

The confusion came about because in a book Casey described doing it small to big. West system directions describe it big to small.
I actually wrote to Casey and he told me his book is wrong, at least the edition I had, and big to small is the current standard.
Yes it seems backwards but for the reasons others have said it is the standard.
In truth with epoxy it probably doesn't make a lot of difference.
davidpm is offline  
Quote Quick Reply Share with Facebook
post #6 of 7 Old 04-02-2012
Senior Member
 
mitiempo's Avatar
 
Join Date: Sep 2008
Location: Victoria B.C. Canada
Posts: 7,487
Thanks: 0
Thanked 94 Times in 85 Posts
Rep Power: 8
   
Re: Fiberglass question

One of the best places to get tips for fiberglass repairs and re-coring as well as many other ideas is here Northern Yacht Restoration | Tim Lackey:* One Man, One Boat at a Time
Click on "Project Logs" - he details everything he does with pictures.

Tim hasn't written a book but he is doing it every day. I don't know if he has read Casey's books - I haven't.

Brian
Living aboard in Victoria Harbour
mitiempo is offline  
Quote Quick Reply Share with Facebook
post #7 of 7 Old 04-03-2012 Thread Starter
Battered and Bruised
 
Silvio's Avatar
 
Join Date: Nov 2010
Posts: 490
Thanks: 0
Thanked 7 Times in 4 Posts
Rep Power: 5
 
Re: Fiberglass question

Thanks everyone. Makes sense once you talk it through, really not what my first inclination would have been though.

Davidpm, it probably was either the book you said or an excerpt from that book that I was recalling as describing the order as smallest to largest.

Cheers everyone!

SV S.S.R.I
It's my happy pill
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Silvio is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

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
Fiberglass repair question huguley3 Gear & Maintenance 13 11-30-2009 05:22 PM
another fiberglass repair question scosch Gear & Maintenance 3 08-05-2008 11:24 PM
Fiberglass repair question merttan Gear & Maintenance 7 06-17-2008 12:47 AM
Question about fiberglass patrickbwells Gear & Maintenance 33 03-28-2007 09:54 AM
Fiberglass Repair Question Fstbttms Gear & Maintenance 11 03-14-2007 12:58 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