Fibreglass Deck Build - SailNet Community
Reply
 
LinkBack Thread Tools
post #1 of 17 Old 11-17-2010 Thread Starter
Junior Member
 
Join Date: Oct 2009
Location: London, United Kingdom
Posts: 28
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Fibreglass Deck Build

Hi guys,

We're looking to replace our teak decks with fibreglass and I'm after your thoughts on what the thickness should be.

The current construction is steel cross braces, plywood panels, then the teak deck.

We'd be looking to replace the plywood panels like-for-like, then coat in West Systems products.

Any thoughts on how thick / many layers of mat we should lay down?

cheers,
nathan
ausnp84 is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 17 Old 11-17-2010
Moderator
 
Jeff_H's Avatar
 
Join Date: Feb 2000
Location: Annapolis, Md
Posts: 6,969
Thanks: 5
Thanked 166 Times in 135 Posts
Rep Power: 10
     
You really have not provided enough information for someone to give you a meaningful answer since the scantlings for a deck are somewhat dependent on the size of the boat, curvature of the deck (larger amounts of curvature in the decks require multiple laminations rather than a single thickness of plywood) and the spacing of the framing.

But also with an unusual construction like your former construction ( steel cross braces, plywood panels, then the teak deck.) you should probably see a yacht designer because the connections to the framing will be more difficult and may impact the correct answer.

Jeff


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay
Jeff_H is offline  
Quote Quick Reply Share with Facebook
post #3 of 17 Old 11-17-2010
Senior Member
 
LakeSuperiorGeezer's Avatar
 
Join Date: Oct 2010
Posts: 551
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 5
 
Would fiberglass on top of this plywood work?
LakeSuperiorGeezer is offline  
Quote Quick Reply Share with Facebook
post #4 of 17 Old 11-17-2010
Moderator
 
Jeff_H's Avatar
 
Join Date: Feb 2000
Location: Annapolis, Md
Posts: 6,969
Thanks: 5
Thanked 166 Times in 135 Posts
Rep Power: 10
     
The problem with simply fiberglassing the plywood, without knowing the design intent would be that you don't know whether the boat was designed with the teak considered as part of the structural spanning system such that the teak and plywood acted as a composite with the decking spanning between the frames and the plywood simply acting as a sheer membrane.

Jeff


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay

Last edited by Jeff_H; 11-17-2010 at 10:03 AM.
Jeff_H is offline  
Quote Quick Reply Share with Facebook
post #5 of 17 Old 11-17-2010
Blue Horizons
 
Harborless's Avatar
 
Join Date: Nov 2010
Location: Jacksonville, Fl
Posts: 1,052
Thanks: 4
Thanked 19 Times in 16 Posts
Rep Power: 5
 
How big is this boat? This will be a pretty expensive process
Harborless is offline  
Quote Quick Reply Share with Facebook
post #6 of 17 Old 11-17-2010 Thread Starter
Junior Member
 
Join Date: Oct 2009
Location: London, United Kingdom
Posts: 28
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Quote:
Originally Posted by Jeff_H View Post
You really have not provided enough information for someone to give you a meaningful answer since the scantlings for a deck are somewhat dependent on the size of the boat, curvature of the deck (larger amounts of curvature in the decks require multiple laminations rather than a single thickness of plywood) and the spacing of the framing.

But also with an unusual construction like your former construction ( steel cross braces, plywood panels, then the teak deck.) you should probably see a yacht designer because the connections to the framing will be more difficult and may impact the correct answer.

Jeff
Hi Jeff,

Appreciate the points. I've emailed the surveyor we used to see if he had any thoughts also, but I figured it never hurts to do the scatter gun approach.

The horizontal stringers are 1ft apart (and about 2" wide), there is minimal curvature to the deck and the plywood is bolted to the steel stringers, then the teak screw to the plywood.

cheers,
nathan
ausnp84 is offline  
Quote Quick Reply Share with Facebook
post #7 of 17 Old 11-17-2010 Thread Starter
Junior Member
 
Join Date: Oct 2009
Location: London, United Kingdom
Posts: 28
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Quote:
Originally Posted by Harborless View Post
How big is this boat? This will be a pretty expensive process
The boat is 40ft with a 10ft x 10ft deckhouse. I've priced it up and the cost won't be ridiculous - we've taken this steel boat on as a project and having stripped the entire interior once, I don't plan on having water ingress thru a teak deck and having to do it again

cheers,
nathan
ausnp84 is offline  
Quote Quick Reply Share with Facebook
post #8 of 17 Old 11-17-2010
Sailors do like Heineken!
 
chrisncate's Avatar
 
Join Date: Jan 2010
Location: Maryland
Posts: 4,574
Thanks: 18
Thanked 34 Times in 34 Posts
Rep Power: 6
 
I like the balsa coring, it comes in small (roughly 2"x2") squares that have a layer of backing. It lays really nice and is easy to cut on site while working with it.
chrisncate is offline  
Quote Quick Reply Share with Facebook
post #9 of 17 Old 11-17-2010
Senior Member
 
RichH's Avatar
 
Join Date: Jul 2000
Location: Pennsylvania
Posts: 3,567
Thanks: 25
Thanked 167 Times in 156 Posts
Rep Power: 16
 
Quote:
Originally Posted by ausnp84 View Post

Any thoughts on how thick / many layers of mat we should lay down?

cheers,
nathan
For structural 'surety' you need to exactly define the dimension of the deck, the dimension from the 'bulwark' to the coachroof being the most important.

A laminated decking needs to be very carefully engineered, as it is essentially a flattened or 'flat-plate' box-beam laminate structure with fixed 'ends' .... quite complicated to design 'well'. A good structural engineer can easily 'back calculate' the original 'intent' of the structural load bearing ability of the deck. So for an amplification to Jeffs recommendation Id further have the OEM deck analysed first, before taking it to a 'boat designer'. That will establish the strength characteristics/function ... and 'validate' the original designers/engineer's (important) FACTOR OF SAFETY. The factor of safety is a 'contingency factor' that is included in structural design so to withstand 'unforseen but probable' maximum loads. Most 'blue water boats seem to 'back calculate' to a Factor or Safety @ 3 or more, 'coastal' boats at 2 - 2.5 FS. etc.

BTW - you DO NOT want to use "mat" for this reconstruction, as 'mat' is only for 'cosmetic purposes', and is essentially non-load bearing form of 'fiberglass'. For this rebuild you want either heavy weight cloth or woven roving .... then maybe covered or overlayed with 'mat' as a cosmetic 'leveling or smoothing' layer. For an ocean capable boat the deck must withstand the impact forces of a large 'boarding/breaking wave' .... . ;-)
RichH is offline  
Quote Quick Reply Share with Facebook
post #10 of 17 Old 11-17-2010
Senior Member
 
poopdeckpappy's Avatar
 
Join Date: Jul 2006
Location: San Diego
Posts: 6,199
Thanks: 35
Thanked 42 Times in 36 Posts
Rep Power: 12
     
Quote:
Originally Posted by RichH View Post
BTW - you DO NOT want to use "mat" for this reconstruction, as 'mat' is only for 'cosmetic purposes', and is essentially non-load bearing form of 'fiberglass'. For this rebuild you want either heavy weight cloth or woven roving .... then maybe covered or overlayed with 'mat' as a cosmetic 'leveling or smoothing' layer. For an ocean capable boat the deck must withstand the impact forces of a large 'boarding/breaking wave' .... . ;-)
This is not entirely correct, it doesn't have any load bearing value but it's not for cosmetic purposes; CSM will give you thickness and stiffness but it's the cloth ( E,S or biaxial ) that will give it strength and is the last layer ( excluding the gelcoat ) in the finish product, that is why they use 4 or 6oz cloth on surfboards, strength and appearence

1955 Blanchard 51 Custom ( I got a woody )

1974 Ranger 33


Lord, give me coffee to change the things I can change and Rum to accept the things I can't
poopdeckpappy 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
Fibreglass and keel replacement questions Cb103 Gear & Maintenance 5 06-15-2010 10:34 PM
choosing the right fibreglass squishface Gear & Maintenance 2 03-17-2009 10:10 AM
Question on Fibreglass repair?? jeffdammeier Gear & Maintenance 2 06-02-2008 06:02 PM
making old fibreglass look new Gex Gear & Maintenance 10 04-19-2006 10:45 PM
Time to build the deck NewsReader Sabre 0 04-14-2006 03:15 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