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Author Foredeck re-core
Jordan Owens
Austin, TX

Boat Name: Grooner

Model/Year: 1970 C22

Hull No. 170

Hailing Port: Austin, TX
01/31/2006 10:32 AM Pacific Time

The plywood on my foredeck is rotten and needs to be re-cored. Should I cut off the top skin of fiberglass and dig out the core from the topside or cut out the liner and replace the core from underneath? I will be sanding the deck and repainting it anyway so I'll be able to fix any cosmetic issues related to cutting the deck from the topside.
What about core materials? Should I use regular plywood, marine plywood, Nida-core, or something else?
Any advice would be appreciated.
Peter
South Daytona, Florida

Boat Name: (Working On A Name)

Model/Year: C-22, 1974

Hull No. 2679

Hailing Port: South Daytona, Florida
01/31/2006 12:16 PM Pacific Time

It is much easier to work from the top, but cosmetically and structurally, it seems better to do all your work from the inside. I have a picture of the cross section of the hull, topsides gunnel (gunwale) and liner if your interested.

Peter
Jordan Owens
Austin, TX

Boat Name: Grooner

Model/Year: 1970 C22

Hull No. 170

Hailing Port: Austin, TX
01/31/2006 1:34 PM Pacific Time

Peter,

Thanks for the advice. I would like to see your cross-sections. You can email me at [email protected]

Jordan
Larry
Greenville, SC

Boat Name: Kemo Sabe

Model/Year: C-22 , 1973

Hull No. 2229

Hailing Port: www.keoweesailingclub.com
01/31/2006 7:35 PM Pacific Time

I re-did the port side of my foredeck from the underside of the deck 4 years ago.. It was done from the inside of the boat's vee birth so
that the deck material wouldn't be disturbed and for
aesthetic reasons. I had lots of good advice from my
friend Dennis Slaton on how to do this as he's done
MANY of these repairs for other folks.

The job itself is not that hard, but what "scared" me
was the importance of doing a good job and that I
lacked the confidence to 'jump' on it without
someone's solid, verbal advice on what should be done.
I really wish that the experience had been documented
in pictures, but I just wanted the 'experience' over
with!!

These are the basic steps that I used for my
successful foredeck, port-side core repair job.

1. Strip the deck of hardware. Strip the boat inside
as all of the work I did was from the interior. If
you're smaller than 6'3" and 240, it'll be easier for
you than me on the vee berth.

2. Identify the specific part of the deck core you
desire to replace from the interior. Make a line
drawing on the interior deck liner where you will cut
it. (A mark to follow with a side grinder. Yes, a
side grinder.) I could
have done the whole foredeck as it would have been
just as easy, but only did the port side
foredeck, following the interior molded pattern at
the mid-deck forward from the upper chainplate.

3. Side grinder. (Not as bad as it sounds!!)I used a
small 4.5" side grinder turned with the blade
vertical, with me lying on my back under the work. I
had goggles and good mask. I also had a GOOD box fan
exhausting on high speed lying over the hatch along
with some good interior light, all for obvious
reasons.

4. Making sure that I had light pressure on the side
grinder, (Never went through the deck, nor even close,
but I was SWEATING THAT!) I followed the lines at the
mid foredeck level, making final cuts toward the
outboard side of the boat. The liner fell on me. I
thought it'd be a pain to pull off. It was a perfect
template for the plywood I'd later cut to replace the
rotted with. Don't cut along the outboard edge of
liner or wood as it's not a problem and will come
loose easily.

5. Remove the liner and rotted plywood. Not a bad
job at all as the wood was rotted and most fell on me.
Remainder could be pulled down manually.

6. Clean underside of deck. Clean hull liner/wood
side.

7. Cut plywood using the liner template.

8. Make measured wooden jamb braces to jam between
vee berth and interior deck. Make PLENTY. Use
anything that you can jamb or jack against the
interior of the deck. Pressure makes
the 5200 set firmly. I 'shaped' the deck by using
these braces. Cement blocks were put on top of the
deck to give me downward force to jamb against. This
gave me the pressure that I sought and allowed me to
'shape'the deck to the correct contour, although
that's not a problem. The deck still retained its
shape even though there was no liner or wood sandwich.

9. Spread 5200 on the back of the plywood and
brace/jamb them into position with all the wooden
jambs/jacks. I think that you could do the liner and
the plywood simultaneously, but I had time, wanted the
5200 to do its job, so did them separately. I gave
the 5200 a LONG time to kick, too long, but it was
January and I had time.

10. Spread the 5200 on the inside of the liner.
Repeat the same process as with the plywood. The side
grinder will leave a gap in the liner the width of the
blade. Make SURE that you smooth out the 5200 that
squeezes into the gap. Smooth it like caulking or use
caulking to make a smooth seam. I plan to put some
nice wooden strips over mine, if I get around to
it!!:))It really doesn't look bad the way it is
and is unobservable for the most part. I guess you
could use something other than 5200 to attach the new
wood and liner, but it works, is not as messy as
epoxy. My deck is like new, doesn't flex and as I
said, I'm afairly 'big boy'!! (addenda 2006: In hot weather now, the 5200 (port side) has become a bit more springy than the starboard side. It is absolutely no problem, but there are others who have used epoxy to repair theirs. You may want to inquire of them how the procedure went. I still like the 5200, however.)


This is what worked for me Someone else may
have done it differently. I'm happy with the outcome.
Hope this might give you a bit of confidence to jump
on the job. Sorry you're having the problem.

Good luck,
Larry


Kemo Sabe
C22, 2229
http://www.keoweesailingclub.com

Aaron M Benham
33a Loomis Hights

Boat Name: Tidely-Idley: The never ending project

Model/Year: 1978 C22

Hull No. 8070

Hailing Port:
01/31/2006 8:13 PM Pacific Time

I suggest that you get a copy of Don Casey's book "This Old Boat". It is a great reference and explains the correct method for replacing core material in a very straight forward and easy to understand way. According to Casey's book, the problem with the method of repair that Larry suggests is that it is only slightly stronger than the top skin of the deck by itself. I think that you would find the $28.00 cost of the book to be money well spent and it would build your confidence in this project as well as many of the other projects you undertake.
Jordan Owens
Austin, TX

Boat Name: Grooner

Model/Year: 1970 C22

Hull No. 170

Hailing Port: Austin, TX
01/31/2006 9:13 PM Pacific Time

Hello Larry and Aaron,
Thanks for the advice. I bought Casey's book "Sailboat Hull and Deck Repair". I think it probably has the advice you are refering to. I don't quite understand why Larry's suggestion would not be very strong. Is it because he suggests 5200 instead of epoxy to attach the plywood?
Larry
Greenville, SC

Boat Name: Kemo Sabe

Model/Year: C-22 , 1973

Hull No. 2229

Hailing Port: www.keoweesailingclub.com
02/01/2006 2:54 PM Pacific Time

Hello Jordan,
As for being strong, I can't say the repair is weak since I weight 240 and it holds me up just fine and has for several years. I will say that it is a bit more springy than the starboard side, (original) but that may be due to the 1/4 inch plywood I used for core; I thought that was what was there. However, on doing it again, I'd go thicker. And, as I said, in really hot summers, the 5200 does get springy, but it an't coming lose and I have so much in there (unnecessary) that the chance of water intruding the whole repaired core is miniscule, I think.

Epoxy is very strong, as everyone knows. I knew it'd be stronger, but I didn't want to deal with all of the mess of the runoff and with the extra expense and the stuff kickin' before I was ready. And, since I had just replaced a through-hull which was embedded in 5200 (I'm still cussin' when I think of the work!:)), I know that it will hold anything, it seems.

Yep, Casey is surely right, but mine works for me, and you will want to examine your options closely. I'd say, like a buddy always said, "Just do whatever floats your boat." :))

Whichever method you use, it is not as big a deal, from underneath, as you'd think. But, like any new job, the anxiety it produces, (at least for me) is for more traumatic than actually doing/completing the task!

Good luck!
Larry
Aaron M Benham
33a Loomis Hights

Boat Name: Tidely-Idley: The never ending project

Model/Year: 1978 C22

Hull No. 8070

Hailing Port:
02/01/2006 8:57 PM Pacific Time

The weakness would not come from the 5200 which is one of the greatest adhesive/sealants around (too good for some applications that you might want to remove later). The problem lies in the fact that the only thing holding the new core in place really is the small bead of adhesive around the edge. The
adheasive/caulk holding the bottom skin in place (which can't be more than 1/4 inch thick and is more likely closer than an 1/8 ") has virtually no inherent strength of its own. In the original construction, you had a solid piece of wood sandwiched between two layers of fiberglass. What has been done is to cut a hole through all but one layer. The core and the bottom skin are simply glued to the top layer with out reattaching the bottom layer in a way that makes it whole again. The way to do that is to use a scarf joint around the bottom( or whichever piece was removed) which is 10-15 times as wide as the laminant is thick. Done correctly and with proper care, the replaced skin will again be one solid piece as sturdy as the original and the new core will be compeatly encapsulated and supported from both sides.
I hope that Larrys approach continues work for him and that he doesn't find himself standing unexpectedly on the Vee Berth. At the very least, I suspect he will find severe crazing of the gelcoat before too long. Good luck, and do try to build that instrument cover in Casey's book. Its a lot of fun. Just make sure you do it outside or your whole house will stink like styrene for a couple of days.
Jordan Owens
Austin, TX

Boat Name: Grooner

Model/Year: 1970 C22

Hull No. 170

Hailing Port: Austin, TX
02/06/2006 9:19 AM Pacific Time

Update: This weekend I enlisted my dad's help. We used a rotozip to cut through the liner about an inch forward from where the deck starts to curve upward toward the cabin. We cut all the way aft of the mounts for the aft lowers. Then we used a chisel to get all the rotten wood out. We also sanded the top surface of the liner. Now we need to get plywood, cut it, and epoxy it back in. I'll let you know how it goes.
Jordan Owens
Austin, TX

Boat Name: Grooner

Model/Year: 1970 C22

Hull No. 170

Hailing Port: Austin, TX
02/13/2006 1:07 PM Pacific Time

Update: This weekend I had help from my dad and my brother. We used the liner as a template and cut new core out of half-inch marine plywood. We sanded the underside skin of the foredeck with a pad sander in an electric drill. We mixed up west system epoxy with slow hardener and thickened it to mayonaise consistency with colloidal silica. Then we spead on the epoxy pretty thick and stuck each new piece of core up and braced it with pieces of 2 by 2's. Then we loaded a bunch of bags of lead shot on top, ran out of shot, and started loading anything we could find including buckets of paint, buckets of water, free weights, etc. Now I'm just giving it extra time to cure. Next weekend comes the liner. I need to buy more epoxy.
Larry
Greenville, SC

Boat Name: Kemo Sabe

Model/Year: C-22 , 1973

Hull No. 2229

Hailing Port: www.keoweesailingclub.com
02/13/2006 4:55 PM Pacific Time

Sounds like you are doing a great job there, Bud!! You're going to have one more good boat when you get the deck back on!
Larry
Michael Barnes
Newtown Square, PA 19073

Boat Name: Gaper Delay

Model/Year: 74 Catalina 22

Hull No. CTYH37550774

Hailing Port: Philadelphia
10/15/2006 3:08 PM Pacific Time

HELP. Okay, I have the same problem and after two years, the boat is still covered and I am part way through replacing the entire foredeck core. I need help and was hoping to find a tradesman experienced at this in the Philadelphia area so that I can move on ! Anyone out there can recommend someone who can help ? someone to do a backyard task with me ? Need to get this done !
Tim Seifert


Boat Name: Mary's Joy

Model/Year:

Hull No. 8281

Hailing Port: Holyrood, Newfoundland
03/21/2010 7:16 PM Pacific Time

What is the thickness of the core? Some people seem to have used 1/4" while others have used 1/2" plywood to re-core the deck.

I am in the process of re-coring the deck. I have removed the liner and old plywood. But what thickness of material do I need for the new core?
Glenn Warner
Jacksonville Florida

Boat Name: Goblin/JuJu

Model/Year: 1981/1972

Hull No. 10369/1222

Hailing Port: Jacksonville Florida
03/22/2010 7:55 AM Pacific Time

As with all things c22, there is nothing standard about the thickness of the core material used by the factory. But 1/2 is, in my opinion, overkill. Go with 1/4 inch.
Aaron M Benham
33a Loomis Hights

Boat Name: Tidely-Idley: The never ending project

Model/Year: 1978 C22

Hull No. 8070

Hailing Port:
03/22/2010 8:26 AM Pacific Time

No matter what thickness you decide be sure that you use MARINE GRADE plywood only.
Greg Baker
Charlotte, NC

Boat Name: Sea Sharp Minor

Model/Year: Catalina 22 - 1984 - Swing Keel

Hull No. 11823

Hailing Port: Lake Norman Sailing Club
03/23/2010 7:32 AM Pacific Time

I don't want to be contrary but I think Aaron's statement about marine grade plywood in this application is overkill. While marine grade does contain waterproof glue, so does exterior grade plywood. Marine grade is also more rot resistant but you are going to encapsulate the plywood in epoxy anyhow. The main difference between marine grade and exterior grade plywood is the spec on voids. Since marine grade is often used on curved surfaces, in order to get a fair curve, voids are not allowed and the grade of wood used, few knots, limited sized knots, harder varieties etc. are strictly spec’d. The price of marine grade is 2 to 3 times that of exterior grade so it is up to you to decide if the cost is worth the gain in an encapsulated environment where the shape is not important.
Glenn Warner
Jacksonville Florida

Boat Name: Goblin/JuJu

Model/Year: 1981/1972

Hull No. 10369/1222

Hailing Port: Jacksonville Florida
03/23/2010 8:39 AM Pacific Time

I would agree with Greg here. Consider that few boats use plywood as core material. Most use either balsa or foam. Water would obviously be detrimental to either of these. As Greg said, the core is not going to be exposed to moisture. If it is, well in time it wouldn't matter what core material you use.
Aaron M Benham
33a Loomis Hights

Boat Name: Tidely-Idley: The never ending project

Model/Year: 1978 C22

Hull No. 8070

Hailing Port:
03/23/2010 12:02 PM Pacific Time

Actually, many boats use plywood as a core material as it is much cheaper thnt balsa or foam which is used because it is lighter than plywood. Remember the main reason any core material is used is to increase the stiffness, not necessarily the strength of the structure.
As for the statement that water won't get into the encapsulated wood, lets remember what caused the problem of the delaminated/rotted core in the first place; yes it was water intrusion in the encapsulated core. Catalina originally used marine grade plywood in the deck, hull stringers, transom and even under the cockpit and the wood still got wet and rotted.
Re-coring the deck is such a labor intensive job that to even think about using anything but the right materials is out of the question in my opinion. Water IS going to get in there and once it does it has no way of getting out short of drilling holes and pulling it out. Using construction grade wood is just asking to do the job again in a few years. The only place I would even consider using standard lumber is for the settee table. It has no place anywhere else on a boat.



Boat Name:

Model/Year:

Hull No.

Hailing Port:
03/24/2010 7:19 AM Pacific Time

Hi all, I recored a deck section on a bigger boat that had used balsa to start with. I used nidacore or something like it from a company in florida. I thought the price was reasonable but I don't remember what it was. The new core is a sandwich of plastic top and bottom with a plastic honeycombed structure in the middle. light but strong. I agree that using the best material is the thing to do, and this plastic will never rot even if water gets to it. hope this helps.
Tim Seifert


Boat Name: Mary's Joy

Model/Year:

Hull No. 8281

Hailing Port: Holyrood, Newfoundland
03/27/2010 4:08 PM Pacific Time

Re-core project is underway now. I have removed the old plywood, as far back as the cabin lights. Haven't yet decided whether to go further back. I will probably replace the forehatch. I just saw a picture of "Miss Kitty" online (nice looking vessel). It seems to have a Lewmar hatch, which is what I am considering. Has anyone experience replacing the standard hatch with a Lewmar (or Bowmar) hatch?
Thanks.
Kendall Boykin
Tampa

Boat Name: MOONDANCE

Model/Year: 1986/C22

Hull No. 3220

Hailing Port: Tampa
08/27/2017 9:01 AM Pacific Time

Not trying to be rude to anyone and I know this is an old thread but do not use 5200 as a structural bond. 5200 is a sealant and should only be used a such. That is just really bad advice. SMH!
Kendall Boykin
Tampa

Boat Name: MOONDANCE

Model/Year: 1986/C22

Hull No. 3220

Hailing Port: Tampa
08/27/2017 9:07 AM Pacific Time

On another note also don't use exterior plywood as it has been pressure treated and will inhibit the bond of the resin. It is also not designed for a marine environment. I really can't believe the bad advice on this page. If you want advice I suggest calling a professional fiberglass repair shop. Most understand how expensive paying someone else to do the work can get and would be more than willing to give advice.
 
 
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