Balsa Core Delamination

[Brewkid]

Colby, got pictures?

[Gilbertsons]

Glad Colby posted (Colby, go to the beginning of the thread....better that pictures ....he has videos!!)

Bob is right that underneath the cockpit floor is a void, I know since I have an inspection plate that I can open to check for water that could be resting on the inside of the hull.

I did a little research and found that CDory starting making the moulded interiors and moulded cockpit LINERS in 2007. I attached a picture of a boat on a trailer with this moulded cockpit liner.

I was also lucky to find a picture in Colby's album in a folder called "Holes in Sole" (Thanks, Colby) I have also included in this posting. If you store your boat on a trailer with the bow up and water comes into the cockpit it will run to the aft of the boat. Since the fuel tank cover was screwed from the fuel tank side into the cockpit liner, water can penetrate and enter the void under the cockpit liner and accumulated on top of the hull. When the bow of the boat is lowered the water that has accumulated runs forward up against the aft cabin wall where it is fiberglassed tabbed to the hull. If it is not watertight in can come into the interior of the cabin at or near the water tank. You may think you water tank is the source of the leak.

Now if John's water tank was mounted with screws into the hull and they were not sealed or properly epoxied into hull, water could have penetrated into the balsa core material of the hull.

Don't how many years they used this construction but if your a 2007, 2008 owner I would install and round inspection port in the floor on the cockpit to watch for water coming into that void.

Scott

[colbysmith]

[hardee]

One of the reasons I like my 2005 C-D Cruiser, no false floor in the cockpit. Yup, if you are standing in the cockpit and there is water on your feet, there is water ni the cockpit. Works like the weather rock that hangs by the DQ in Sequim. If your feet are dry, look aft. If there is no water to be seen, the cocckpit is dry. (Mostly, most of the time -- disclaimer for the lawyers in the crowd.)

Harvey
SleepyC

[thataway]

I liked the removable 2 piece floor which was available in the 2004 thru 2006 era. It was an option. Sometimes a pain to pull it up, but you had the level floor, no standing in water, and could clean under easier. The disadvantage was it added more weight to the boat.

Before that, I used the dri deck with closed cell foam anti fatigue mats from Sam's club on the cockpit floor, and that worked well.

[Moxieabs]

Widget had a leak at the deck fill plate for the water tank. It is positioned so any rain water on the gunwale runs over the deck plate. The water would finds it's way under and around the tank?

[Brewkid]

For those following along, I added 5 new videos.

https://www.youtube.com/channel/UCZXdxUrTrFpNsryE0aeXl9g/videos

Goodnight!

John
Scallywag

[ssobol]

[tomherrick]

In the meantime, users can sort the videos on Youtube from oldest to newest. If you've clicked on Scallywag's videos to see all of the thumbnails, there is a "Sort BY" button on the upper right. Click on that and sort by Date added (oldest).

[Brewkid]

SSOBOL,

Easy fix. Numbers added for your viewing pleasure!

John
Scallywag

[thataway]

I reviewed the thread and the videos again. Thanks for a comprehensive history of your work!

The question in my mind, is there any other penetration of the inner side of the hull which allowed water to penetrate the inner hull, and get to the Balsa core beyond the water tank? You had the screws holding the water tank down. I don't see any wires so there should be no screws into the core of the hull under the table.

Any water leaking from the water tank would be kept in the compartment where the tank was, with the fiberglass interior having been fully tabbed in as you found by cutting along the tabbing at the bottom of the area where the glass tank was secured. Could it have been water leaking in from around the water fill, or from a loose hose to the fill of the water tank? Still this does not seem like it would have been enough to cause the damage that you have, unless a considerable amount of water stood there for a long time. Looking at the balsa as it is in the Video #4 & #5, it is definitely separated from the hull side of the core--and that suggests to me that both freeze / thaw cycles and boat pounding were involved. Under normal conditions the balsa is firmly adhered to the inner surface of the hull The fiberglass interior gives more stiffness to the hull, than the plywood interior does.

Back to the flat cockpit deck and the aft cabin bulkhead; It looks as if the aft cabin bulkhead is glassed into the inner surface of the hull inside the cabin. I believe it should be well tabbed in on the cockpit side, under the flat deck also. I have seen boats where this was absent, or broken down.

Is there water under the flat deck? Many of the owners who have these flat elevated decks have put inspection plates in to remove water. But you would need holes to allow access--and there should be none there. Also no screws into the inner floor there. It looks as if you have the straps properly screwed into the glassed in cleats and not the core. (maybe outboard into the core?) The unused thru hull fitting aft is a concern--and should be opened up to be checked.

Personally I would go back with Balsa core. I would want the entire hull to be the same material. The balsa is going to be less weight than the Coosa board. (Urethane foam with fiberglass fibers, or the "BlueWater" with woven roving and glad fibers.). If you want you can put glass and epoxy "barriers" between sections of balsa core. I am aware of boats made entirely of balsa (planked), then glassed inside and out and after over 40 years absolutely no core problems. In the 20 boats we cut up (Hurricane Ivan damaged boat) in our studies on delamination and instrumentation, there were many up to 50 years old, with absolutely no core damage, and good adherence of the balsa core. Of course these had no holes in the outer laminate, and had used solid glass or other materials in the way of cleats and other penetrations.

As for cutting in by the door, if you cannot reach its with the Fein type blade, you may be able to use a flexible shaft on a Dremel or Rotozip type of tool, and a rotary blade or cut off wheel. Also air powered die grinders work well getting tight places, especially with a small cut off wheel. The tabbed in glass often separates well, when you have cut most of the other surfaces, and one or two areas remain. The tab bonds are secondary, and not as strong as primarily lay up bonding.

Keep up the great work, along with good videos.

[Brewkid]

https://youtube.com/channel/UCZXdxUrTrFpNsryE0aeXl9g

Back to chipping away!

[thataway]

You mentioned vacuum bagging and I assume resin infusion. Do we know for certain that vacuum baggings was done for the layup of the 2008 boats? Certainly there is no primary bond between the mat adhered to the Balsa and the outer hull. Almost as if the first layers (mat and roving?? of solid glass had cured, and then the balsa core put in to a contaminated surface. Lets say that the laminating resin had wax in it by mistake. I don't know the lamination schedule of that specific boat.. I suspect it will no longer be available.

Some boats which are vacuum bagged there is a two step process. Also if not done properly resin can not flow to all areas. Just a little kink in a tube can resin starve a significant area.

You are doing a great job--and it must be very disheartening to find more wet core.

I have the same "General" moisture meter and I have found the relative moistures are quite accurate in fiberglass.

A sub set of all of this may be the suggestion that all marine surveyors do a moisture meter on the inner hull in the cabin. (unless there is obvious water sitting there or has been there in the last few hours.)

[garyf]

The things of nightmares...

Has anyone considered dipping their boat in a giant vat of Flex Seal?

Kind of a joke, kind of not. Having the older model cruiser where water collects forward in the cockpit at the bulkhead, I'm wondering if there's anything I can do to add extra protection in that area. So far, I haven't seen any evidence of delamination... but there are some super fine stress cracks down there right at the "joint" of the bulkhead - too fine and seemingly different materials involved so the usual gel coat repair that I'm used to probably wouldn't apply down there.

[Brewkid]

Bob,

Honestly I have no idea. I'm just making assumptions on my very little fiberglass knowledge and would think your hypothesis correct. I just skimmed off a section of the bubbled area (you'll soon see in my video) and was surprised to find a sunflower seed husk underneath. Who knows the state of the company in 2008. It could have just been one disgruntled employee that day that was lacking attention...

Disheartening, yes. I'm trying very hard to keep a positive attitude but if you ask me at this moment if I'd buy another cored boat my answer wouldn't be positive....

All,

I do want to be clear, that although there seams to be lay up issues, I'm not pinning the water damage on that. I've cleared out enough balsa from under the back bulkhead and the void under the back deck may have been the culprit. The rear bulkhead appears to be glassed off from the floor, and I cannot feel or see a seam from the underside so I'm not sure what the sealant seals off where the deck and bulkhead meat....

As far as upkeep of the boat. She's always been covered, never spent more than a week strait in the water and other than fished hard, she's been babied. Aside from pulling every screw and re-bedding them, I'm not sure what else I could have done. The water could have found its way in before I purchased it.

I'm also uploading my survey for anyone interested in what one looks like.

Edit, after looking at the build albums. Pictures look pretty close to my year.

http://www.c-brats.com/modules.php?set_albumName=album1219&op=modload&name=gallery&file=index&include=view_album.php&page=1

http://www.c-brats.com/modules.php?set_albumName=album1219&id=IMG_2072&op=modload&name=gallery&file=index&include=view_photo.php


R/
John
Scallywag.