Balsa Core Delamination

Brewkid · Posted: Sat Jan 04, 2020 10:12 am Post subject: Balsa Core Delamination

As previously mentioned in another post, here is my YouTube channel following the repair of my 2008 22' Cruiser.

https://www.youtube.com/channel/UCZXdxUrTrFpNsryE0aeXl9g?view_as=subscriber

If anyone has ever pulled the dinette out of the port side and successfully re-glassed it back in I'd love to ear from you. If the videos don't describe enough I'd be glad to fill in where needed.

John
Scallywag

Da Nag · Posted: Sat Jan 04, 2020 10:53 am Post subject:

Wow...first time I've seen that.

I looked back a bit through your posts, but didn't see any explanation as to the source of the water. Did the tank or one of the fittings leak?

Brewkid · Posted: Sat Jan 04, 2020 11:52 am Post subject:

Da Nag,

Coming from you that really say's something! The tank has never showed any signs of leaking, condensation yes, but leaking no.. Starting on the 14th after I get back from taking my wife to Denver I plan on removing the dinette and exposing more of the sole to find the culprit. As of now my assumptions are the screws that were not beaded were the conduit to the balsa, but as for the water source only time and a saw will tell....

Wish me luck,

John
Scallywag

localboy · Posted: Sat Jan 04, 2020 5:14 pm Post subject:

Sucks and confusing since it is INSIDE the boat. The source will be interesting.

thataway · Posted: Sat Jan 04, 2020 7:07 pm Post subject:

Looks like a lot of core which was damaged. Is this all from one source or several? My guess is several.

Nice surgical work!

As for glassing in the dinette, I suspect that you mean the base for the table, seats etc. I have not done it, but I have built in furniture like that from scratch. You want to get rid of all of the screws and the L brackets thru out the boat. Put pieces of fiberglass mat and cloth to replace them. I did this in several of my C Dorys.

You cut the old tabbing to the hull off with a Fein type of reciprocating blade (Dremel, etc cheaper) so you can cut flush with the hull. Then grind with 24 or 36 to the hull--not into the hull, removing the original tabbing. Same for on the Decaboard. Then lay layers of mat start with 4" wide, then 3" wide. Put a fillet in the corners (you can used thickened resin, or space the plywood slightly off the hull, with a closed cell foam, which does not dissolve in resin). You don't want hard spots on the hull. I prefer epoxy for better bonding, but since you have a large area, and much will be new, polyester will work fine.

Any specific questions, feel free to PM or e-mail.

pcg · Posted: Sat Jan 04, 2020 10:15 pm Post subject:

How did you discover that something was wrong? What made you start investigating?

Gilbertsons · Posted: Mon Jan 06, 2020 7:59 pm Post subject:

Hi John,

I have a 2008 C-Dory with the moulded fiberglass interior and cockpit floor. My guess is that it was not from the water tank that caused your damage, although that could be an entry point for water through the screw holes you mentioned. If water is entering somewhere under the cockpit floor it could be running forward to the aft cabin wall and penetrating down at another point that is compromised.

I subscribed to your youtube channel and I think it would be great if you get something back from www.boatworkstoday.com.

I'm sending you a PM as well.

Scott

Brewkid · Posted: Mon Jan 06, 2020 11:29 pm Post subject:

Group Reply!!

Localboy, you said it!

Bob, it does look like its one source but will take a little more cutting to know for sure. The dinette in my year is all molded glass, no screws or brackets that I've seen yet. Thanks for all the info past and probably in the future!

PCG, I noticed a small soft spot just inside the companion way on the port side. You could more feel the soft spot while the boat was running, which is a little unnerving. I already had a trip planned for Nootka Sound and wasn't going to miss it so I put off the exploratory surgery until I got back. I believe once a small amount of water got in, hydraulics played its part and now here I am...

Scott, you may very well be right, but I hope not. Our year of boats the aft deck and cabin bulkhead are not glassed. Instead they chose to caulk the joint. If water did find its way into the joint it could be possible. I re caulked the joint 2 seasons ago with 3M as a preventative. The original caulking was not the best of material and since I'm an aviation guy it didn't stick around for long. This possibility has already crossed my mind but I'm just keeping my fingers crossed that it's not the issue. Also the damage is not centerline, but off to the port side...So lets talk worst case. I'm going to pull the dinette, then cut open the floor where it's soft under the tank. If the core delamination goes under the deck...well deck is next to be lifted out. I'm not happy about any of it but shes mine and I'm going to fix her!

As far as Boat Works Today. I'm getting the opportunity to talk with Andy on the 18th. I'm pretty excited to get his input and from what I've heard from others, hes great at instilling confidence, so I'm stoked!!!

Thank you everyone that has taken the time to post, or send me messages. It's easier to keep on track when you have others to keep you accountable and on task! I'll be dropping more YouTube videos as soon as I get back on the 14th and will drop a link here when I add a new one for anyone interested in following along.

John
Scallywag

Blue Rose · Posted: Tue Jan 07, 2020 11:33 am Post subject:

John-
It was painful to watch your video and see the core damage caused by water intrusion. IMO a C-Dory is a great boat but it's susceptibility for core rot is a potentially fatal flaw in its design.

Have you tried using an endoscope to explore the extent of the damage? I would try that first before I cut the boat apart.

Also from the video, it appears the tank's outlet hose may have been bent at a sharp angle. You may want to pressure test the water tank and hoses to see if you find some leaks that are not visually obvious. That's how I found the location of a crack in a plastic welded fitting on my water tank.
Jim

Gilbertsons · Posted: Tue Jan 07, 2020 12:05 pm Post subject:

John-

It's great that you checked where the deck meets the aft cabin bulkhead. There are many posts about that.

What I am talking about is other ways it can go under the cockpit deck. I found the CDory or the last owner secured the vertical fuel tank covers in place by putting a screw from the fuel tank side into the cockpit deck to hold it in place. This can allow water under the deck which can run forward to the aft cabin bulkhead. If the aft cabin bulkhead cabin was not tabbed water tight then water can run into the interior sometimes near the water tank giving the appearance that the water tank is the leaking culprit.

I not sure what you mean about the aft deck is not glassed. My 2008 has a glassed deck with a balsa core. I know that because when I bought it I have a round 4" inspection port installed and I can look into the void under the aft deck and see the hull and if any water is in there. Also when you say you might have to "lift out the deck" I assume you can do that only after you first cut it away from the boat. Mine looks fiberglassed in with the step and everything. Referring back to your videos it looks like your 2008 deck is the same as mine.

It would be great in other 2008 model owners chimed in on this.

Scott

lloyds · Posted: Tue Jan 07, 2020 3:15 pm Post subject:

Got a hunch if he is having a problem like that a lot of others do too. Just haven't been discovered yet. Why would they go to only caulking the bulkhead? Seems like asking for trouble, especially with a boat that isn't self bailing.

thataway · Posted: Tue Jan 07, 2020 7:39 pm Post subject:

I am also amazed that the aft cabin bulkhead is not glassed in (caulked instead) on some of the 22's. There have been some 25's which have had water intrusion into the interior cabin apparently also not having the aft cabin bulkhead properly tabbed into the hull (should be on both sides).

Thanks again for all of your documentation. It is helpful to all of the C Brats.

I had not realized that all of your cabinets were glassed in--and that explains the magic of tank removal! My advice using the Fein type of saw remains as the best and proper approach.

tomherrick · Guest

John,
When my boat evinced water in the transom core I got out my woodworking moisture meter. Not to determine percentage of moisture, but simply changes in density of the fiberglass and core. Moving the meter across transom and cockpit deck surfaces I made marks where the values were 10, 20, and 30-percent, then connected the dots of equal value. That gave me a pretty good indication of where the problems were, and weren't.
My 2-cents if you were considering acquiring one for your project would be to get the cheapest pinless meter you can find - unless you're gonna get into serious woodworking. Accuracy doesn't matter here, just identifying the changes.

colbysmith · Posted: Thu Jan 09, 2020 8:38 pm Post subject:

Don't mean to hijack the thread, but perhaps this is related. I noticed today on Midnight Flyer, while removing mice nests and cleaning up that issue, that where the cockpit inside gunnel connects to the back of the cabin bulkhead, it is somewhat delaminating. This is on the starboard side. My next thought was I wonder what is between the inner gunnel, which almost appears to be part of the raised floor, and the outer gunnel hull? Is it possible for water to run down inside of that area, and if so where does it go? The second thought is what is beneath the raised floor? I have had some water in that area, but is that just an open space, with the actual coring between outer and inner hull fiberglass beneath it? Colby

thataway · Posted: Thu Jan 09, 2020 9:50 pm Post subject:

Mice nests? Use Bounce Dryer sheets or moth balls to prevent them. On edit or maybe not? I did some internet research and the big tabs put in public urinals seem like the best repellant--see thread on the mice/and mink. The mice are very destructive.

There is nothing between the false side and the hull, his is a void. Yes water could run down inside. It may go under the the floor. I am not sure how the floor is secured to the side--if at all. I believe that your boat is one of the early fixed floors. My late 2006 22 had the removable floor. As I under stand there is a void under the glassed in floor. I believe that some access should be made for that area, to be sure that no water is pooled there.

As to the what you call the inside gunnel, I believe is a separate piece and it has been tabbed in and then faired and gel coated. With time there can be "stress" cracks there from thick gel coat. But it is possible that there is some break down of the tabbing. I will be happy to take a look at Hontoon. There was a photo not too long back of a 22 being built which showed the underside of the deck mold, and as I recollect there was also the aft bulkhead attached there. Not sure if this was the way it was done and the floor was included in your boat.