Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 13-07-2014, 09:16   #16
Registered User

Join Date: Jul 2011
Location: Alameda, CA
Boat: C&C Newport 41
Posts: 586
Re: Plywood deck core work

while balsa is certainly, historically, the core material of choice, one should ask why they want an organic material in proximity to water...

decks are always subject to rotting because they 'lots' of holes into the core (deck hardware).

using a foam core will provide a higher threshold to the presence of water (via the aforementioned screw holes), be easier to work with / cut (form) to the size and shape of the replacement and provide better adhesion for the resin.

remember that poly wont adhere to epoxy so if 105 was there, bite the bullet, pay for the 105 and stick with it. when doing deck work, i would recommend extra slow (209) hardener which will help with self leveling and better saturation.

if you used foam core you would not need the marine plywood layer.

i am sure u already know that re-coring a deck is NOT fun. do more research and make smart decisions and you wont be redoing the core in 5 years.

gl.


-steve
__________________

__________________
ssanzone is offline   Reply With Quote
Old 13-07-2014, 09:59   #17
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,363
Re: Plywood deck core work

Quote:
Originally Posted by Ujin View Post
Zach, I did realize the difference in height. However, it was a thought. If 1/2 should take the bend then that would be the most efficient route. That's definitely good to know about 1/2 inch.
Is your ply ok now? if so.. don't put all that stuff over it, just dry it and reglass it properly. at least you can tell it's condition from underneath also, and it's been able to breath rather than sit in a core and rot with heat and humidity.
__________________

__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 13-07-2014, 10:30   #18
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: Plywood Deck Core Work

I think Zack has given you a lot of great info.

Just remember that any hole through a deck that is not solid fiberglass needs to be sealed with epoxy. If your deck is mainly solid except for a few wet spots I would just repair the wet spots, scarf the new plywood into the old and then follow Zack's advise on covering. Remove every piece of hardware and ensure that every hole is sealed with an epoxy annulus. Make the annulus thick enough that when you tighten the hardware bolts the pressure wont compress the plywood.
__________________
The Blue Dot Campaign. This Changes Everything.
DeepFrz is offline   Reply With Quote
Old 13-07-2014, 11:09   #19
Senior Cruiser
 
sneuman's Avatar

Cruisers Forum Supporter

Join Date: May 2003
Location: Jamaica
Boat: Tayana 37 Cutter
Posts: 3,167
Images: 37
Re: Plywood deck core work

Quote:
Originally Posted by ssanzone View Post
while balsa is certainly, historically, the core material of choice, one should ask why they want an organic material in proximity to water...

decks are always subject to rotting because they 'lots' of holes into the core (deck hardware).

using a foam core will provide a higher threshold to the presence of water (via the aforementioned screw holes), be easier to work with / cut (form) to the size and shape of the replacement and provide better adhesion for the resin.

remember that poly wont adhere to epoxy so if 105 was there, bite the bullet, pay for the 105 and stick with it. when doing deck work, i would recommend extra slow (209) hardener which will help with self leveling and better saturation.

if you used foam core you would not need the marine plywood layer.

i am sure u already know that re-coring a deck is NOT fun. do more research and make smart decisions and you wont be redoing the core in 5 years.

gl.


-steve
Yes, yes, of course. But it's always a cost/benefit analysis. Divinicell (or whatever) costs waaay more. With a crappy plywood core, my deck lasted 30 years, even with 1,000+ tiny screw holes to pipe the water right in. So, recoring it with balsa, sans the screw holes (and with properly bedded deck hardware), I figure it will last for at least 30 years -- probably a lot longer. Either I or the boat (or both) will be long gone by then.

Just sayin'
__________________
sneuman is offline   Reply With Quote
Old 13-07-2014, 12:30   #20
Registered User
 
Ujin's Avatar

Join Date: Jun 2009
Posts: 19
Re: Plywood Deck Core Work

A quick note on holes in the deck, there are twice as many as necessary. All the deck hardware was pulled and repositioned at some previous point in time. And incidentally all the deck hardware that was remounted failed and was pull up by pv and holes left open.
Many of the original bolts were left in and the heads sheered off. Some of the holes had duck tape then glass over while others just glassed over. The areas of the deck that look the best have lots of grey wood.

So to scarf in a few places would get me by, but the framing is what I am most worried about by letting it go and getting a little at a time.

And to make the world more challenging the bulwalk where the glass turns up and should bond to is a rough mess. Under that edge of the decking, most of which has just fallen apart, is the clamp bonded to the hull to support the deck and the rub rail. The deck is through bolted to that clamp every few feet.

I don't want to think about replacement of that!

I posted on the balsa manufacturers forum for input on using balsa or foam over ply, but have not had a response as of yet.

Thanks for the idea of using slow resin for the levelling.
__________________
Ujin is offline   Reply With Quote
Old 14-07-2014, 10:31   #21
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,363
Re: Plywood Deck Core Work

Someone correct me if I'm wrong, but I think poly will mechanically adhere to epoxy. like paint etc. But yes, it wont chemically bond like epoxy on epoxy. I don't think poly on poly necessarily chemically bonds together when done well after the original part has cured either. (like if you are replacing a bulkhead or tabbing in something in an older boat.) The resin required for a chemical bond cannot be finishing resin and must still be tacky for the chemical bond. It does stick well if done correctly though.
__________________

__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Reply

Tags
core, deck, plywood

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not 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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Plywood for core RainDog Construction, Maintenance & Refit 57 03-02-2014 12:57
3/4 Balsa Core = X/X Plywood OLDSON Construction, Maintenance & Refit 31 20-05-2013 06:19
To balsa core or not to balsa core? fbchristo Multihull Sailboats 135 04-02-2009 15:13



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 23:57.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.