Reply
 
Thread Tools Search this Thread Display Modes
 
Old 10-27-2017, 05:19 PM   #1
Senior Member
 
SeaMoose's Avatar
 
City: Anchor Pointe, Ohio
Vessel Name: Sea Moose
Vessel Model: 1976 34' D/C Taiwanese Trawler
Join Date: Oct 2007
Posts: 196
Recoring Cabin Roof Seeking advice

Hello All
A quick background - I've recored my decks, and most of the house already over the 17+ years I've owned this boat. So at the least I am a qualified amateur.

76 Marine Trader/CHB/Taiwanese Tub. Started peeing that ugly brown water off the back of the cabin top this season.

Once in the barn for the winter, cut the top layer of glass off right behind the seats and found the usual little blocks of luan the Asians loved back then, held together by polyester resin:



Of interest the top layer glass was 2 layers of 18 oz. cloth, with typical poor saturation, something plastic like - spray on truck liner maybe, and yet another 18oz layer cloth, maybe 2, clearly done with epoxy. Very heavy and zero adhesion between the original top and the truck liner I pulled the layers apart by hand! SMH what people do to "fix" things...

But I digress. This area was dry. Leaving a strip about 2' wide in place I opened up the back and sure enough it was rotted black biomass mush.



Bear in mind these are initial cuts to get the rotted goo out before winter I'll clean these to the edges before I start recoring.

To my surprise the bottom layer of the fiberglass sandwich is a paper thin layer of perhaps 6oz cloth, so thin and so fragile I've already poked a hole in it scraping the last of the rotted goo off.

Such poor construction doesn't surprise me at this point but it's still pretty pathetic. Under that is about a 2" air gap and the composite board that's the interior roof.

I'm inclined to take the whole thing out, put foam insulation boards in the air gap to insulate things, then recreate the bottom layer with two layers of 6 oz cloth, then a proper core of divinicell, or end grain balsa, followed by a solid layer on top (probably a 6 oz initial layer, followed by any needed leveling and 2 18oz layers.

Curious to hear from others who have done this job, how it was built, and how they recored it.

Specifically:

What construction method did you find?

Did you leave the paper thin bottom layer?

Did you cut the whole top off, or do it in sections. From what I can see if I cut the whole top off the house will collapse...

What did you recore with? I've used 3/4 Marine ply everywhere else but seems a little heavy to put on top. If three or four really heavy people want up there I'll tell them no :-)

I expected to find a proper fiberglass sandwich not some cheesy paper thin bottom layer and an way overbuilt top layer. How they managed to make such a paper thin bottom layer on the ceiling - to support the weight of the luan blocks - that was a real trick. It's not chop gun glass which is what they used on the house exterior walls.

Thanks for reading. The boat's in the barn for the winter, and I'll resume in the Spring so lots of time to decide how to proceed.

And yes, yes, I know it's a waste of money to restore one of these things but it's too late now and I no longer care...
__________________
Advertisement

SeaMoose is offline   Reply With Quote
Old 10-27-2017, 05:33 PM   #2
Guru
 
MurrayM's Avatar
 
City: Kitimat, North Coast BC
Country: Canada
Vessel Name: Badger
Vessel Model: 30' Sundowner Tug
Join Date: Jul 2012
Posts: 3,889
Hero badge in the mail. Going to get snacks and a comfy blanket to watch the show
__________________

__________________
"The most interesting path between two points is not a straight line" Murray Minchin
MurrayM is online now   Reply With Quote
Old 10-27-2017, 08:02 PM   #3
Senior Member
 
boomerang's Avatar
 
City: Kilmarnock VA
Country: united states
Vessel Name: YellowBird MMSI 367769170
Vessel Model: 1978 Mainship m1 #149
Join Date: Apr 2016
Posts: 377
Hey Sea Moose here's what we did. It isn't a Taiwanese-built boat but it shared the same crappy coring trait. The first pic is of the old coring exposed with the top layer of glass removed. The next is of the thin bottom layer of the floor which required the supports we put on the underside in the salon shown in the last pic.
Attached Thumbnails
Click image for larger version

Name:	badcorelongview.jpg
Views:	304
Size:	197.1 KB
ID:	69754  
Attached Images
  
__________________
-Shawn-

https://shawnandlizboats.blogspot.com/
boomerang is offline   Reply With Quote
Old 10-27-2017, 08:34 PM   #4
Senior Member
 
boomerang's Avatar
 
City: Kilmarnock VA
Country: united states
Vessel Name: YellowBird MMSI 367769170
Vessel Model: 1978 Mainship m1 #149
Join Date: Apr 2016
Posts: 377
Here's a couple more of the coring we used. The wood is marine plywood used anywhere there was going to be something fastened & the white is Nidacore where nothing would be fastened. It was all bedded in epoxy. In hindsight, we probably should've gone with all marine ply (the lines you see are where I cut scarfs in the ply 1/2" deep so that the wood would conform the the crown of the deck). The small savings in weight wasn't worth all of the mudding to try to make the pieces fit together at the seams. The whole project was a major son-of-a-bitch but having my wife help made it doable...
Attached Thumbnails
Click image for larger version

Name:	100_0916.jpg
Views:	291
Size:	118.7 KB
ID:	69757   Click image for larger version

Name:	100_0922.jpg
Views:	310
Size:	110.8 KB
ID:	69758   Click image for larger version

Name:	100_0926.jpg
Views:	302
Size:	116.8 KB
ID:	69759   Click image for larger version

Name:	100_0917.jpg
Views:	373
Size:	199.3 KB
ID:	69760  
__________________
-Shawn-

https://shawnandlizboats.blogspot.com/
boomerang is offline   Reply With Quote
Old 10-27-2017, 09:01 PM   #5
Veteran Member
 
JimW's Avatar
 
City: Birmingham
Country: Shelby
Vessel Name: CLASSEA
Vessel Model: 1988 Defever 41T
Join Date: Apr 2017
Posts: 72
Recoring Cabin Roof Seeking advice

Donít get the luan squares, must have been plentiful, had the same on the deck and fly bridge of our DeFever 41, tracking down soft spots.Click image for larger version

Name:	IMG_0028.jpg
Views:	276
Size:	72.7 KB
ID:	69761Click image for larger version

Name:	IMG_0029.jpg
Views:	263
Size:	63.8 KB
ID:	69762

Went back on the fly bridge with coosa board with 2 layers of glass on top and 1 layer on the bottom air vacuumed, then glued and glassed down the seams and then will spray a slick coat then skid coat.

The coosa board and glass will hopefully be a 1 and done repair. Also used it on a couple of soft spots on the deck. Good stuff, solid fix.
Attached Thumbnails
Click image for larger version

Name:	IMG_0014.jpg
Views:	264
Size:	119.3 KB
ID:	69763   Click image for larger version

Name:	IMG_0030.jpg
Views:	272
Size:	64.1 KB
ID:	69764  
JimW is offline   Reply With Quote
Old 10-28-2017, 12:11 AM   #6
TF Site Team
 
Insequent's Avatar
 
City: Brisbane
Country: Australia
Vessel Name: Insequent
Vessel Model: Ocean Alexander 50 Mk I
Join Date: Mar 2012
Posts: 1,756
On my foredeck we used two 1/4" layers of marine ply, with the joints staggered. The thinner ply allows it to easily conform to the curvature. We put 1.5oz CSM on the lower skin first, which was the proper thickness. On top of the ply we put 1.5oz CSM, 2 layers of 24oz woven roving and lastly 2 layers of 1.5oz matte. This ended up with the same thickness of deck as the balsa cored original, about 7/8". I did not replace the teak on top. Overall it is thick enough, but not as stiff as it would have been with teak on top.

For the boat deck, firstly we drilled 3/8" holes to map out where the balsa was wet, and where it was still dry. This resulted in about half the deck not needing to be disturbed. We replaced the balsa core with closed cell foam. All good, but now an un-repaired area has the dreaded brown water emerging into a below deck light fitting, fortunately on the side walkway and not internally. I need to locate the water entry point, seal and re-bed the offending fittings. I believe it is just a small area and will defer deck repair for the time being.

For the OP, I think core preference is closed cell foam then marine ply. I would avoid balsa. You really want to limit the spread of any water that gets in, and have a core that is resistant to rot as well.
__________________
Brian
Insequent is offline   Reply With Quote
Old 10-28-2017, 10:10 AM   #7
Senior Member
 
SeaMoose's Avatar
 
City: Anchor Pointe, Ohio
Vessel Name: Sea Moose
Vessel Model: 1976 34' D/C Taiwanese Trawler
Join Date: Oct 2007
Posts: 196
Thanks everyone for the responses so far. When I started repairing the rot some twelve years ago I planned on recoring everything with starboard but after doing a small section of the foredeck with it I switched to Marine Ply and never looked back.

Boomerang thanks for the pictures and explanation. I am now confident in my plan to do this in sections so I don't have to build a support structure.
SeaMoose is offline   Reply With Quote
Old 10-28-2017, 01:40 PM   #8
Guru
 
Rogerh's Avatar
 
City: Niceville, FL
Country: USA
Vessel Name: At Last
Vessel Model: 1990 Jefferson 52 Marquessa
Join Date: Aug 2013
Posts: 700
SeaMoose, do you have a sag in the affected areas and are you trying to take the sag out with the support structure?
Rogerh is offline   Reply With Quote
Old 10-28-2017, 07:08 PM   #9
Senior Member
 
SeaMoose's Avatar
 
City: Anchor Pointe, Ohio
Vessel Name: Sea Moose
Vessel Model: 1976 34' D/C Taiwanese Trawler
Join Date: Oct 2007
Posts: 196
No sag. Iím planning on doing it in sections so I donít need a supporting structure.

I am surprised how weak the initial construction is though, I was expecting something like the decks where there are teak struts forming torsion boxes .vs. the cabin roof which so far appears to be held up by one support beam in the center.
SeaMoose is offline   Reply With Quote
Old 10-28-2017, 08:21 PM   #10
Senior Member
 
boomerang's Avatar
 
City: Kilmarnock VA
Country: united states
Vessel Name: YellowBird MMSI 367769170
Vessel Model: 1978 Mainship m1 #149
Join Date: Apr 2016
Posts: 377
You're lucky. Your support beam keeps the shape of the deck consistent for you. Our deck was sagging so we had to not just brace the ceiling/flybridge floor but we also had to establish the correct amount of crown so that the bridge & seating would fit correctly when we reinstalled it.
It's a good thing that we were able to do the work ourselves because boatyard repair labor would've exceeded the worth of the boat!
__________________
-Shawn-

https://shawnandlizboats.blogspot.com/
boomerang is offline   Reply With Quote
Old 10-29-2017, 08:22 AM   #11
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 17,388
You are not kidding.

At marina labor prices, all the projects togetther probably exceed the boats initial cost easily, if not 150%.

I couldnt afford to cruise if I had to pay for repairs.
psneeld is online now   Reply With Quote
Old 11-01-2017, 01:30 PM   #12
Senior Member
 
boomerang's Avatar
 
City: Kilmarnock VA
Country: united states
Vessel Name: YellowBird MMSI 367769170
Vessel Model: 1978 Mainship m1 #149
Join Date: Apr 2016
Posts: 377
Quote:
Originally Posted by psneeld View Post
You are not kidding.

At marina labor prices, all the projects togetther probably exceed the boats initial cost easily, if not 150%.

I couldnt afford to cruise if I had to pay for repairs.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Yep. That describe our situation quite succinctly!
__________________
-Shawn-

https://shawnandlizboats.blogspot.com/
boomerang is offline   Reply With Quote
Old 11-05-2017, 10:14 AM   #13
Guru
 
Mule's Avatar
 
City: Fort Pierce
Country: USA
Vessel Name: Florita Ann
Vessel Model: 1982 Present
Join Date: May 2014
Posts: 1,912
Quote:
Originally Posted by boomerang View Post
You're lucky. Your support beam keeps the shape of the deck consistent for you. Our deck was sagging so we had to not just brace the ceiling/flybridge floor but we also had to establish the correct amount of crown so that the bridge & seating would fit correctly when we reinstalled it.
It's a good thing that we were able to do the work ourselves because boatyard repair labor would've exceeded the worth of the boat!
Did the same Repair. Used plywood. You are/have doing/done a better job than I. I should have done more on the first layer. I had 30 cinder blocks to put a crown on the bridge deck and numerous 4x4’s to avoid collapse. I still ended up with a void per the hammer.

Great sea boat. Weakness is rudder too small and too far forward, for me the v berth sucks. I lived aboard 4 years and NEVER had a friendly thing to say about the v berth. Galley, Head, cabin, deck space All good/great.

All Mainships I have encountered have these issues. It was my understanding that the riggers at the dealer level largely caused these messes by not preparing the attachment points properly before putting #12 and #14 screws in. Often without even 5200. I truly HATE end grain balsa to this day.

You had it good, your 1st Mate looks better and more competent than the collection of homeless substance abusers I had for help... my community outreach program
Mule is offline   Reply With Quote
Old 11-10-2017, 06:35 AM   #14
Senior Member
 
boomerang's Avatar
 
City: Kilmarnock VA
Country: united states
Vessel Name: YellowBird MMSI 367769170
Vessel Model: 1978 Mainship m1 #149
Join Date: Apr 2016
Posts: 377
Mule, I just read your last. Too funny! I'm glad that phase of the rehab is over with...while we were there in the summer heat on the hard in a boatyard I considered becoming a substance abuser myself. You're correct about my help looking better than most boatyard workers, though.
__________________
-Shawn-

https://shawnandlizboats.blogspot.com/
boomerang is offline   Reply With Quote
Old 12-30-2017, 07:29 AM   #15
Veteran Member
 
JimW's Avatar
 
City: Birmingham
Country: Shelby
Vessel Name: CLASSEA
Vessel Model: 1988 Defever 41T
Join Date: Apr 2017
Posts: 72
Click image for larger version

Name:	IMG_0217.jpg
Views:	156
Size:	49.0 KB
ID:	71610Click image for larger version

Name:	IMG_0218.jpg
Views:	161
Size:	46.9 KB
ID:	71611Click image for larger version

Name:	IMG_0219.jpg
Views:	156
Size:	29.8 KB
ID:	71612

Finished product!
JimW is offline   Reply With Quote
Old 12-30-2017, 08:41 AM   #16
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 17,563
As most have found out bending good ply is not easy.

The simplest method is to use 1/4 inch in staggered layers.

Between layers roofing tar is the perfect glue/gap filler.

3 - 4 layers of 1/4 is enough for up to a 10 ft width span, ringed SS nails for assembly and screws into the rib structure for strength.

A layer or 2 of 1 1/2 mat with polly resin makes the roof waterproof easy to paint.

If there is no foot traffic the white house trailer roof paint does a fantastic job of reflecting heat. It is far too soft for use as a sole.

Beware , only 50-70 sq ft of coverage per gallon.
FF is offline   Reply With Quote
Old 12-30-2017, 04:44 PM   #17
Senior Member
 
SeaMoose's Avatar
 
City: Anchor Pointe, Ohio
Vessel Name: Sea Moose
Vessel Model: 1976 34' D/C Taiwanese Trawler
Join Date: Oct 2007
Posts: 196
Roofing tar, very interesting idea. Thanks.
SeaMoose is offline   Reply With Quote
Old 12-31-2017, 06:25 AM   #18
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 17,563
"Roofing tar, very interesting idea. Thanks."

STOLE the concept from home boat building sites that have similar problems with new construction as we do repairing our boats.

Sadly I forget which NA presented the idea.
FF is offline   Reply With Quote
Old 12-31-2017, 07:10 AM   #19
Senior Member
 
boomerang's Avatar
 
City: Kilmarnock VA
Country: united states
Vessel Name: YellowBird MMSI 367769170
Vessel Model: 1978 Mainship m1 #149
Join Date: Apr 2016
Posts: 377
I'm having a hard time warming up to the roofing tar laminate repair job. As much labor as was involved in the recoring of our bridge floor, I felt better using marine-grade plywood, marine resins & conventional marine techniques. I wanted everything to be as stout as possible & I know that was accomplished going the route I did. I realize there's more than one way to skin a cat (is that phrase no longer PC?...sorry cat lovers) but I wasn't going to use roofing tar on a boat to save $500.
The extent of materials we purchased at the home store for our repair was limited to sandpaper & rollers.
__________________
-Shawn-

https://shawnandlizboats.blogspot.com/
boomerang is offline   Reply With Quote
Old 01-01-2018, 05:47 AM   #20
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 17,563
The 1/4 layers of ply are held together structurally by the SS ring nails.

The purpose of the tar is to obtain some bonding , but mostly to have a surface that stops rot in any air space , as no built up laminate is perfect.

Its not the bucks saved , its the longevity of the roof / deck that counts.
__________________

FF is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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





All times are GMT -5. The time now is 04:20 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012