Deck Core

[Kong]

Construction and restoration question. How does one know if the deck core is in need of replacing or repair. I always see mention of core rot and replacement in these topics. How does one determine if there is rot in the balsa core without digging past the layup?

[AGUESS]

Kong, I had a lot of balsa rot on my 1966 Classic 18. There were several things that I noted.
1. small cracks in the gel coat on the deck. 2. The balsa around the vent holes were damp.

I started digging out the balsa at the engine vent holes and worked my way forward. All the balsa was wet. The boat had been inside for about a month and the balsa was still damp. Replaced all the balsa from the back to the front.

You will have to test some area and then reglass the balsa if it is ok.

Good Luck.

Alex.

[GeneD]

The way most of us find out that the balsa is shot is by the deck rigidity, or lack thereof.
I found out by walking on the front deck. The surface was visibly deflecting.
This is not an easy job. Once there on the scene...a man does what a man has to do. But...it is not easy.

[Kong]

Well now...I wondered about walking on the deck! I don't know if I would normally do that on fiberglass boats. I'm real nervous about doing this on my '70 Century. The deck on my Sw 16 is weak. I don't know if I would dare walk on it. Unfortunately the boat is in storage about 300 mi from where I live and I can't further inspect. Good idea regarding vent hole inspect. What are the ramifications of have the boat in use with less than strong deck? Will boat flex (yikes!) at speed and in waves? Thanks for your responses!

[MattM]

There are alot of boats that I would never walk on the deck of. You should have no problem at all walking all over your classic though, if it shows any sign of giving way, your core definately has problems.

[Kong]

Here's an idea I picked up when I worked at Penn Yan Boats. What if I cut a PVC pipe (or cardboard tube soaked in resin) - say 1-1/2" dia - lengthwise; lay it in transverse across the underside of the deck and then seal it in w/mat or roving. Gunwale to gunwale every 8-10". Rather than rip out all that balsa. Wouldn't add that much weight. What do you all think??

[Forrest]

Owen, I don't think you have to worry about print-through when doing a re-core job. It's the original in-the-mold job that will print-through since all of the polyester is not fully cured at the time the coring is set into to place. Once it fully cures, some shrinkage occurs which often times causes the outline of the balsa blocks to slightly show in the gelcoat.

------------------
Forrest

[Kong]

I did see some 'shadow lines' in the gel coat and wondered what had caused that. There are indented lines in the gelcoat going roughly bow to stern on the starboard side. Could be the print thru mentioned.

Dave.

[Scott Pearson]

I would replace the core. By using PVC or whatever you just making a bandaid. Its still going to be soft inbetween the outer layers of glass. Luckly my deck was fine. I did redo the hatch with new balsa. There arn't any lines or anything like that from the new balsa. I also had about 30 holes from a piece of wood that I screwed to the hatch to get the bow back in the hatch and non of them came back. Its 100%!

I just painted the deck this past weekend and it came out great. I have to tell you that I think I know why Donzi put a strip down the center of there boats. You can see faint lines down the center from the why they glassed them from the factory. Once I striped the deck you would never know they where there.

(NJ)Scott

[Hot foot]

I am in the process of recoring the the deck of my '67 16. A previous owner had screwed pressure treated beams under the front deck, however the fibreglass had disbonded from the balsa on both sides and the deck was still springy. In addition the balsa was saturated with water and could be squeezed like a sponge. The only long term fix is to replace the core. I was originally going to use a structural foam core such as Klegecell but after hearing that Donzi recommends balsa I am going to stick with it. Does anyone have experience with Vinylester Resin for this application, I have spoken to a few people who say it is easier to use , cheaper and just as strong.

[Kong]

Thanks for all the input. Makes a LOT of sense that any suppport layed in over the rotten core and old layup would just separate from the core and just hang there! Sometimes it is very hard for me to see the simple logic of doing it right! I'll let you know if and when I 'pop the top'!

Dave.

[Scott Pearson]

Dave,
For what its worth, Its not that big of job removing the deck and flipping it over. You can do it in about 3-4 hours with some help. Get at least 7 people to help you remove it. Its not thats its heavy its just akward. Need to support the bow. Also leave the railings on it helps to have somewhere to hold.

(NJ)Scott

[Len]

Scott Pearson:...you said the stripe down the center of the deck covers up the glasswork? I thought the decks and inner cockpit liner were made in one piece with the ski rack and foot/leg area as add ons. Am I wrong. What is the format here? Any help would be appreciated. These are not a two piece lateral lay-up that are joined once popped?,...are they?

[Scott Pearson]

Len,
They are one piece. The way Donzi built the deck was with Balsa and they didn't carry it all the way across the deck. They stopped the balsa about 8-9 inches from the center. So it leaves an impresion from where they stopped. Its just they way the glass and balsa cures.

(NJ)Scott

[Kong]

Scott, During lift off of the deck do you have to break a resin seal between the deck and the hull? That would be the only problem that might hold me up. Penn Yan used to mix wood dough and resin and putty it on the hull side then drop the deck and let it 'kick'. I would not want to pull that deck off!!

[BigGrizzly]

Our 16 had sum between the dech and hull at front of the cocpiton left and right side of the top and the crossmember at the floor by the fuel tank. I had a little calk under the rubrail between the hull and deck

Randy

[Scott Pearson]

Dave,
There should only be some caulk. The only places it should be glassed in what was metioned in the earler post. About 4 pieces of woven around your floor storage area, 2 pieces up in front of the ski rack and 2 pieces on the sides of the ski rack. Best thing to cut it with is an Air hack saw.

Good luck!

(NJ)Scott

[GeneD]

No balsa betweent the stripe?
Not on mine. Balsa all across. That is where it (the rot) was the worst. It came in through the fuel fill hole.

------------------
GeneD
007
Melbourne, Florida

[PaulO]

My '73 18 is as Scott describes: balsa does not meet in the center of the deck. Perhaps that is one of the few changes. Maybe to solve the fuel filler hole rot problem that Gene describes?
PaulO

[Scott Pearson]

Paul is right. Im sure that is the reason the changed that design. Ahhh gotta love it...Donzi worked all the bugs out on the 66's.


Laughing!!!!!!!


(NJ)Scott

[Kong]

Hey - That's great!! I got a '67!! All that worrying for nothing. Uh---Huh! All this talk is making me think twice about leaving my boat in storage far away. Sniff...All I have are my photos and some resin in my cellar that I can whiff from time to time!

[RickSE]

The coring on my 96 goes all the way across and does not stop in the middle.

[This message has been edited by RickS (edited 01-26-2001).]

[AGUESS]

Kong,

When I took the deck off my 66 Classic 18, there were several places you had to be carefull. First, the ski locker was glassed to the hull at the front. Second, Where the deck sat on the hull, there had been epoxy or some other glass material poured. I had to break it up with a chisel and hammer. Third, glass was wraped from the deck to the hull at the same location as the epoxy. Fourth take a light, get into the engine compartment and look forward to see if any other glass is wraped from the deck to the hull.

I pulled the top using two comealongs. I made a wooden support for under the front and rear of the deck and went through the lift rings.

Good Luck.

Alex.