Frequent Sea, Cored decks and the fungus farm

T

thataway

Active member
Please understand that I purchased this C D 25, knowing that there were defects and am moving foreward to completely recore the cockpit deck--most likely with Nida-core. I have written in the past about the importance of sealing with epoxy the edge of any cored materials--especially the balsa core which supports rot. I discussed this issue with Bret Reynolds customer relations at C Dory and he assures me that boats built today will not have these problems, and that each hole in the boat is sealed properly. I hope this is true.

I had been told that a person jumped or stepped hard from the gunnel onto the cockpit deck and the deck cracked. Apparently the previous owner didn't report this to C Dory, as he should have. As I took the deck apart it is aparent that there was rot in the core of the deck, and when the person stepped on it or jumped, that there was no structural support under the superficial layers of glass, thus it cracked. This initial crack was near the edge of the port deck hatch--I am quite sure that this core had already detiorrated before the person stepped there. These cracks should have been repaired immediately--and any good technician would have discovered underlying rot. What i did find was that rot with wet core and detiorration was out as much as 4 inches from all of the other hatches and openings. The area of the cracks are up to 18" out from the hatch. PHOTOS are in the "Thataway" Album, page 5, photos 99 thru 104.

All cored openings, MUST have any core material removed from the edges of the hole. This area MUST be filled with epoxy to seal the balsa.
This is compounded by two other defects: The hatches were bedded with silicone sealant--which has no place as a sealant in a place where it may be constantly wet, and the screws were directly into the thin fiberglass of the deck and into the core--allowing another opening for moisture to get into the balsa core. This was compounded in this boat by the fact that the boat sat out in the weather, with no cover over the cockpit. The boat was stern down, so water would drain out--but I suspect that snow accumulated in the cockpit and as it melted there was also more water intrusion.

I figured--well at least this only happens in the deck, not the hull bottom. Wrong! I found that the macerator pump is screwed into the balsa core of the bottom of the boat. I have sounded this area out carefully and find no delamination, but will rectify this error by filling with epoxy and properly bedding the mounts of the pump.

Moral--all deck fittings thru balsa must be sealed--not with gel coat or Bostic--but with epoxy after small amount of core material is removed.
Do not let any water sit on decks or cockpits of boats. If cracks develope, or areas seem to be a potential problem, report this to the manufactuer. I have been studying cored hulls and decks (as part of the ultrasound instrumentation project) for a number of years--and this is one of the worst cases I have seen. The cockpit deck will be rebuilt with Nida-core, a honey comb synthetic material--lighter and stronger than balsa.
 
Bob – it looks like you have a challenging project ahead of you. I have no doubt that you will end up with a boat, that is better than when it was new.

Good luck and keep us updated.
________
Dave dlt.gif
 
Brent,
I hadn't even thought about that--but heck, with the deck being "half the boat" and Dave's lead, why not a CD 28?--ok I would have to get a different trailer...I am already about 6" over the end of the bunks--I agree with Dave, that the hulls are very stiff, but don't want to push it too far!

I'll think I'll by pass that for now.
 
I have simular rot issues around the deck plates on our 04 25ftr. I too discovered poor or no sealing of the hatches, 75% of the screws would not hold anything etc. When my boat went back to our "C-dory authorized repair station"(dealership) I got a jim dandy repair. Yep they slathered 5200 on the exposed deck cutouts and put in larger screws!
I'll be doing my own repairs from this point on, but i did learn something. Simply attaching the word's "factory or dealership" is no guarantee of quality work!
Mike
 
Mike,
Now you have to remove that pesky 5200! I would remove the plates and hatches, then take a screwdriver and see if there is any moisture or rot. Moisture will be apparent as you press on the balsa. I suspect that the edges of the hatch area was sealed with Bostic--the same stuff used on the various water hoses (yep found some on the holding tank hoses, when I replaced the macerator pump yesterday). Double hose clamps work better!

There are good urethane sealants which are not "perment"--such as 4200 and some of the Silka products.

Hopefully there will be no rot, and that the screws just "worked" the hole to a larger diameter....
 
I have used the DeBond--it works moderatly well. (The other alternative is a hot wire to cut the 5200. What I removed were a set of plastic windows with wide flanges. I put the DeBond on the top edge and slowly worked a putty knife under the flange, putting in more DeBond. I have several "slicks" which I have also used for this purpose. It worked well on the top, where the DeBond could sit and desolve the 5200. The problem was with the bottom of porthole flange--and since the debond didn't work as well as it did on the top and sides, I took out some of the fiberglass. That was farily easily fixed--and the new windows went in with 4200.
 
Well, we have about 1/4 of the cockpit deck removed. (I have a gal helping me because of my cardiac situation), and she will continue to work on the boat, if I am laid up after what ever proceedure I have Friday).
Even though we have had no water in the boat for 5 days, the balsa core, beyond the rotted area (rot about 5" from the edge of the hatch, and wet core to about 10" from the edge of the hatch). We are removing the entire outer floor for a fore and aft direction of 40", from about 6" back of the hatch to well in front of the fuel tank inspection plate. All of this gets back to solid dry core.

I was surprised; the only glass over the core on the outside (top) was one layer of 1 1/2 oz mat! There was no cloth. There was thick gel coat, "non skid pattern". This is the thinest outer deck laminate I have ever seen (we have disected about 30 cored decks in our studies of deck failures). The new deck (all of the cockpit will be reglassed, incuding the part which will still have the intact balsa core) will be composed of B 1708 biaxial glass cloth (this has 3/4 oz mat on the bottom, then layers of bundles of glass cloth laid at 45 degrees--to a spec of 17 oz: greater strength than woven roving. Under this will be 1" Nida-core (which has mat on both surfaces so that the polyester will adhere well to the hex core) and then laid in a layer of 3/4" oz mat on top of the old inner skin which we are cleaning and will reuse. This will be at least 10 times stronger than the origional cockpit floor. The weight will not be any more, because of the lightness of the core material (vs the heavy weight of saturated balsa core).

We probably will not replicate the factory "non skid". Although this can be done without a mold, it is probably better to just finish the cockpit floor smooth and then apply Awlgrip with the glass spheres for non skid.

Considering what we have found, if anyone has a boat of this year/construction and you find any crack in the cockpit floor or possiable water intrusion, I strongly recommend immediately reporting it to the factory for advice on repair.

I also rewired the main circuits on the console. The previous owner had some how destroyed the fuse pannel. Not only did we upgrade the fuse pannel, but we also relocated a sterio which intruded into the bunk area, and covered the hole with a block of King Starboard, which now holds a Link 10 battery moniter system. All wires on the console are now labled and traced so we have a circuit diagram. Next we will put in a second main wire from the battery banks to the console and finish the electronics installation. (Furuno Radar, Garmin GPS/chart plotter, Hummingbird Fish Finder, and Lowrance fuel flow guage). A fresh water shower will be added to the transom well--a swim step will be added, and probably a bracket for the 15 hp Honda kicker.

I had 3 experts on fiberglass repair look at the transom and all agree that there is no major problem. The stress cracks are the same as we see in all of these boats, as well as some gel coat cracking over the hull to deck joint (poor secondary bond)--We will repair the stress cracks. Most likely we will put several layers of tape over the hull to deck joint with epoxy to be sure it stays water proof. Then we will rebed the cap over the transom.
 
Bob, you are working under my feet and you are still over my head.....I need to hire you as a boat survivor to inspect my 2005 25 foot Dory..........Keep us up to date with pictures>>>Keep your life jacket on...Tucker
 
Alasgun":25yw7cpm said:
I have simular rot issues around the deck plates on our 04 25ftr. I too discovered poor or no sealing of the hatches, 75% of the screws would not hold anything etc. When my boat went back to our "C-dory authorized repair station"(dealership) I got a jim dandy repair. Yep they slathered 5200 on the exposed deck cutouts and put in larger screws!
I'll be doing my own repairs from this point on, but i did learn something. Simply attaching the word's "factory or dealership" is no guarantee of quality work!
Mike
Click to expand...

If your "Factory authorized repair station" is who I think it is, you are far better off doing your own repairs.
 
This post literally gave me nightmares last night. Kept dreaming that I found some black mold beneath my gas tanks. I started tearing up my floor down to the core and the rot kept going and going. The dream kept waking me and I only got 3-4 sleep last night. Scary.
 
Bob

Good luck and speedy recovery with your med procedure.
Drs make poor patient b/c they know too much. Be careful they dont cut you in half!
 
I have a 2004 25 c-dory I also have deck rot also rot on bulk head were holding tank hose goes through also rot in supports for deck at drain holes Rich Reynolds said c-dory will fix all my problems I asked them to replace all of the rotting wood no to just patch .
 
The position I have from Brett Reynolds is that the 2003 C Dory does not have a transferiable 5 year warantee. That C Dory would cover the transom repair, because it was reported and they were in negotiations --actually had hired someone to do the repair (but he was so slow it was not done).(As far as we are concerned there is no transom problem we have discovered thus far) Since the previous owner had not claimed the deck problem under warantee, C Dory would not cover it, due to non transferability of the warantee. Unfortunately the previous owner thought that boats just broke when you jumped onto the deck, and had not considered that there was a core problem which caused the deck fracture. C Dory would cover the cockpit deck, if had to be removed to fix a leaking fuel tank. But so far I don't have evidence of the tank leaking thru the bottom--there are fumes from the fuel level sender and that will be taken out, and rebedded with form-a-gasket. I don't know about filling problems, since I will not fill the boat until I take here to the PNW and fill before launch.

Very interesting about the bulkhead problem--and something I had not considered. Have you cut an inspection plate into the bulkhead or floor to access this cut out. I don't know how the "stringers" (factory will not call them stringers, since they are not structural) which separate the fuel tank
and holding tank. Most boats are built with plywood spacers or stringers, which are covered with a layer of polyester and glass, then the limber holes (which allow the water to drain from various compartments) are cut out--and either not sealed, or covered with gel coat. Neither of these are satisfactory.

The beauty of the old C Dory 22 was that it was not subject to any of these problems. The wood was tabed in to the glass on the bottom of the boat. However in my 25, the cabinets are held in place with screws into the hull bottom, not with tabbing. I will probably remove the screws, drill out and then fill the holes, and use fiberglass tape to secure the cabinets.

Please feel free to ask technical questions. There have been a number of responses off list--mostly from folks who do not want their boat identified.

A good place to start reading about cored hulls are the series of articles by David Pascoe--an outspoken Marine Surveyor:
http://www.yachtsurvey.com/cored_hull_bottoms.htm
http://www.yachtsurvey.com/structuralissues.htm
http://www.yachtsurvey.com/core_materials.htm
http://www.yachtsurvey.com/more_on_cores.htm
http://www.yachtsurvey.com/searay_balsa ... ottoms.htm
http://www.yachtsurvey.com/structuralissues.htm
http://www.yachtsurvey.com/latent_defects.htm
http://www.yachtsurvey.com/HiTech.htm
http://www.yachtsurvey.com/materialsagain.htm
http://www.yachtsurvey.com/internal_hul ... bility.htm

And you think my post gave nightmares? Read these!

Hopefully this, along with photos and diagrams will explain the problems.
In the past C Dory had avoided these problems with cored hulls and decks, by simple construction and not putting holes in many areas which had the potential of water standing and a cored deck or structure.

These problems can be prevented, and after found, can be cured, if they are found in time. If this occures in the hull, then the boat will be damaged, and this is why I am concerned about thru hulls and screws into the boat's cored bottom.

Bob Austin
 
Bob,

Are there any publications you can recommend where I and others can see how to use fiberglass tape to do the same fix you are describing. I had been wondering about possible problems from all of those screws.

Thanks for sharing all of your knowledge and expertise.

Bill
Edgewater, MD
 
You can purchase a pretty useful booklet produced by the West System guys that covers most basic fiberglass repairs. I bought a copy at West Marine for just a few dollars. Tabbing is a pretty easy project and is usually hidden, which makes it a good starter project. Still, it's important that its done right. Otherwise, the flexing of the boat will break the bond that the tabbing has with either the boat or the cabinetry. At that time you'll have not only another tabbing project, but a pretty good grinding project as well.
 
With the tabbing, I like to put a fillet or radius of either foam or filler material where the corner of the bulkhead meets the hull. This gives a smooth radius and prevents a hard place on the hull. You need to grind to clean glass on the hull, and probably rough up the surface of the bulkhead or cabinet. For tabbing, using 4 to 6" wide pieces of 4 to 6 oz cloth laminated with epoxy. Half of the material is on the hull and half on the cabinet. The strongest would be to tab the entire bottom of the cabinet on one side. You can use several pieces 4 to 6" long as an alternate. Of course when the manufacturer goes to a molded interior this attatchment of the wood with screws is eliminated.

I agree that the West System epoxy literature is excellent. Some basics are on the internet: http://www.westsystem.com/

The tabbing is much less than building in bulkheads, were you have to both put in fillets as well as taper the layers of glass. With polyester one often uses alternate layers of mat and cloth (or woven roving) which are deminishing in width, to spead out the load.

Bob Austin
 
Not only are the West Systems products excellent, but they also have (or did have) an excellent training program in the use of their products.

About fifteen years ago I took a three day professional boatbuilders repair school at their Bay City plant. The correct application of their product and different techniques were covered, including vaccuum bagging for laminations.

What I found especialy helpful was the "wetting out" of holes drilled in end core balsa: sealing exposed wood with their product to prevent water from entering.

Also, when drilling holes for adding deck gear, such as chocks or water fill plates, they recommend drilling the screw holes oversize and then filling them with epoxy with filler material, such as their microballoons. This adds to the strength of the bond. Before placing the screws in the wet epoxy, spray them with PAM, which acts as a release agent in case they would have to be removed. Or, if PAM is not used, place the tip of a hot soldering iron on the screws for a minute and the epoxy is softened enough to remove the screw.

Shortly after we got Valkyrie home, I removed all deck gear and wet out the holes with epoxy and then reinstalled the gear. I also removed the rubrail and wet out all of those screw holes, as well. When doing that, I found a number of nonused misdrilled holes and filled them with an epoxy paste made West Systems epoxy and their microballoon filler.

The Gougeon Brothers, who own West Systems, actually started their company to develop an epoxy that had the sheer strength to hold the laminated baldes of wind generators together under tremendous loads. Jan, the younger brother, is an accomplished singlehanded sailor who has a beautiful laminated wood trimaran that is coated with West System epoxy.

I always carry one of their "Six Packs" for quick repairs on Valkyrie.

Nick
"Valkyrie"
 
Great post Nick--and this is what should be done on all boats! One can also wax the bolts, and use the epoxy as a "nut"--I don't do that for load bearing applications, but for trim it works great.

I have posted 7 more photos on page 5 of Thataway Album (photos # 105 thru 111) The notes are pretty much self explanitory and give views of the laminate, as well as the bad deck area grossly cleaned out. Today my friend will finish cleaning the bottom glass, put in a layer of mat, wet out with polyester and then lay in the Nida core--it will also be wet out with resin--and the bottom layer actually fully bonds with the mat and present glass. Tomarrow (with good weather) she will get the layer of biaxial cloth- laid, and begin fairing the sides. The deck will be painted with two part Awlgrip--we don't like the agressive non skid, and will use micro glass beads, which are much easier to clean and on the knees, our feet and dog's feet.

This will be my last post, until I come home from the hospital. I have asked Marie to put a post on the thread wishing me well--thank you all!

Bob Austin
 
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