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Frequent Sea, Cored decks and the fungus farm
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Bill.Secure



Joined: 26 Aug 2006
Posts: 118
City/Region: Edgewater - Turkey Point
State or Province: MD
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: Barnacle Bill
PostPosted: Thu May 10, 2007 5:32 pm    Post subject: Looks like I need to do same preventative fix Reply with quote

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
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mrw90



Joined: 17 Jan 2006
Posts: 40
City/Region: Bellingham
State or Province: WA
PostPosted: Thu May 10, 2007 5:44 pm    Post subject: Reply with quote

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.
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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Thu May 10, 2007 10:23 pm    Post subject: Reply with quote

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

_________________
Bob Austin
Thataway
Thataway (Ex Seaweed) 2007 25 C Dory May 2018 to Oct. 2021
Thisaway 2006 22' CDory November 2011 to May 2018
Caracal 18 140 Suzuki 2007 to present
Thataway TomCat 255 150 Suzukis June 2006 thru August 2011
C Pelican; 1992, 22 Cruiser, 2002 thru 2006
Frequent Sea; 2003 C D 25, 2007 thru 2009
KA6PKB
Home port: Pensacola FL
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Valkyrie



Joined: 09 Jan 2005
Posts: 1028
City/Region: Loudonville
State or Province: OH
C-Dory Year: 2005
C-Dory Model: 25 Cruiser
Vessel Name: Valkyrie II
Photos: Valkyrie
PostPosted: Fri May 11, 2007 7:13 am    Post subject: Reply with quote

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"
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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Fri May 11, 2007 12:42 pm    Post subject: ho Reply with quote

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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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Wed May 16, 2007 12:56 pm    Post subject: Reply with quote

The Nida-core is in place. All exposed balsa from the old deck has been sealed with epoxy and the area between the Nida-core and balsa is filled with epoxy. The Nida-core is laid in place with a layer of 1 1/2 oz mat, over the previous inner laminate (1 1/2 oz mat and toward the bilge is 18 oz roving one layer). Next, another layer of 1 1/2 oz mat will be laid where necessary to make the new core exactly flush with the existing deck. All of the gelcoat in the areas where we step has been ground off, and the biaxial cloth will be laid on top of that. Finally this will be faired and either regel coated or alwgripped. (which ever is easiest). It is interesting to note that there were several "impact" areas over the intact dry balsa core, where the single layer of 1 1/2 oz mat had been damaged when some object was dropped on it (Maybe a heavy fishing sinker?). With the new Biaxial cloth, the new cockpit floor will be stronger than the orgional by a factor of at leat 10 fold and resistand to any impact damage.
The last photos in the "Thataway" Album show the Nida-core in place, and the cut out for the bilge pump access, to show the structure of the Nida-core.
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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Thu May 17, 2007 6:28 pm    Post subject: Reply with quote

I have posted photos of the Nida-core deck glassed in place at the last of the Thataway album. We decided that 12 oz biaxial cloth is more than adequate--considering that the origional had only 1 1/2 oz mat. There is also a photo of the biaxial cloth. The fibers are bundles oriented at 45 degrees to the other set of bundles, sewn/knitted over a layer of 1 1/2 oz mat. This is laid down over the balsa and Nida-core, and saturated with resin. The Nida-core has a mat surface--also about 1 oz--so these bond well.

The next stage will be to fill and fair with a medium density filler--then decide of we are going to gel coat, with cabasol added for stiffness and try and replicate the agressive factory finish, or just roll on the Awlgrip urethane with glass beads. The latter is easier on the feet--the former will probably wear better at least initially. I like to put one layer of Awlgrip with beads, then put another layer of Awlgrip without beads to help seal the beads in place. If we use the Awlgrip, we will put an epoxy primer on first.

At this time the deck is at least 6 times stronger than it was initially and is waterproof--no more core rot. We will also fill any Nida-core edges with epoxy, although this is not essential, it is an extra precaution.
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BrentB



Joined: 15 Jul 2006
Posts: 4419
City/Region: Greenwood
State or Province: IN
Photos: BrentB
PostPosted: Thu May 17, 2007 6:56 pm    Post subject: Reply with quote

Great job.

You are Bob Thataway of This Old Boat but too late to cut it half.

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Brent Barrett
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C-batical



Joined: 08 Apr 2004
Posts: 201
City/Region: Pinckney
State or Province: MI
C-Dory Year: 2004
C-Dory Model: 22 Cruiser
Vessel Name: C-Batical
Photos: C-Batical
PostPosted: Thu May 17, 2007 7:09 pm    Post subject: Reply with quote

Hi Bob:

I live up in Michigan and don't have the available sources for the Nida Core product that you apparently have down in FL. I will be starting a similar project on an old Shamrock 20 ft. center console. I am sorry if I missed your source of materials in this posting or other similar postings, but would you please be so kind and provide a bill of materials and list their sources for this project. Thank you for your help in this regard,

Sincerely,
Rollie/C-Batical

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Rollie/C-Batical
Pinckney, MI
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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Sun May 20, 2007 7:22 pm    Post subject: Reply with quote

I got my Nida-core at Advanced Plastics--there is a warehouse in Elberta Alabama about 5 miles from my home. I purcahsed one 4 x 7 foot sheet one inch thick for about $69, including tax. The biaxial cloth and mat can be obtained from any fiberglass supplier--as can the polyester and epoxy resins. http://www.nida-core.com/english/order_list.htm allows online ordering. You might contact Nida directly for a local source. There is a fair amount of boat building in Michigan and I am sure that thee is a local supplier near you.

I posted five new photos. The first two are the finish on the new cockpit floor. It is rolled out polyester resin/gel coat with a mohair roller. The mixture was about the consistancy of coolwhip, we did add wax to this mixture--one of the few times we do this--and we added cabasol to get the proper consistancy.

The second photo is the epoxy sealing of all hatch openings, even with the waterproof honey come.

The third photos are photos of the holes drilled to find out the extent of water intrusion in the lower transom from the screws holding the transducer mounting bracket. It appears that silicone was used as the sealant. (I don't think this was factory done). The next photo, I have cut out the 3 x 3 section of the lower transom, and removed about 1/8" of plywood, and about one inch of balsa core. The Balsa core was under a layer of glass mat (separated from the transom plywood). This is properly done. But it illustrates what happens when you get water in a core. We will remove all of the wet core, fill with epoxy and then relaminate the outer skin of the transom with epoxy. Bottom paint will be applied. There is also a photo of a piece of Starboard which I will cross hatch (for ahesion of 5200) with a dovetail bit (small Dremel tool type) and screw into the transom. The new transducers will be then screwed into the Starboard--and there is no risk of water intrusion. This is fairly easily done, if caught early enough.
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C-batical



Joined: 08 Apr 2004
Posts: 201
City/Region: Pinckney
State or Province: MI
C-Dory Year: 2004
C-Dory Model: 22 Cruiser
Vessel Name: C-Batical
Photos: C-Batical
PostPosted: Mon May 21, 2007 8:28 am    Post subject: Reply with quote

Bob:

Thanks for the information. I had been on the Nida-Core web site but was not sure of the product or thickness you used. I will contact the corporation to find a source here in Michigan. Fiberglass and epoxy products are not a problem. Thanks again for your help.

Best regards,
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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Mon May 21, 2007 8:27 pm    Post subject: Reply with quote

For the deck re-lamination we used polyester resin. For the Transom, we are using epoxy, because of its greater bond strength. The deck is all in compression and there is mostly primary bonding. We did use epoxy to seal the edges of the core (although this is not really necessary, I prefer to do it
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matt_unique



Joined: 27 Feb 2007
Posts: 1881
City/Region: Boston
State or Province: MA
C-Dory Year: 2007
C-Dory Model: 255 Tomcat
Vessel Name: Napoleon
Photos: Napoleon
PostPosted: Tue May 22, 2007 10:10 am    Post subject: Response from factory?!? Reply with quote

I'm just catching up on this thread. Has there been a response from the factory? It is totally unacceptable to have this kind of damage and poor construction practice. Who is responsible for QC at the factory for this kind of thing?

I have been researching C-Dory for my next boat purchase. This definitely changes my opinion.

--Matt

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Captain Matt
Former owner of Napoleon (Tomcat) Hull #65 w/Counter Rotating Suzuki 150's.
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mikeporterinmd



Joined: 15 Sep 2006
Posts: 645

State or Province: MD
C-Dory Year: 2002
C-Dory Model: 22 Cruiser
Vessel Name: Shelly IV
Photos: Shelly-IV
PostPosted: Tue May 22, 2007 11:19 am    Post subject: Reply with quote

Apparently the factory hasn't caught on to the concept that you don't want
threads like this hanging around unresolved. But, you can also read about
plenty of problems with much larger boats, too.

Google "c-dory core problems" and see how that issue was resolved.
While those of us with older boats will need to solve the problem, we
know it is not a huge problem, either. Good factory response.

(In case google chamges, the link http://www.c-brats.com/viewtopic.php?t=1679&postdays=0&postorder=asc&start=0
comes up.)

Mike
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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Tue May 22, 2007 1:39 pm    Post subject: Reply with quote

In the case of the CD 25, Frequent Sea, the previous owner failed to recognize that there was a problem, even though the deck was cracked. He also didn't contact the factory until the boat was for sale, and at the urging of Forum members about the transom problem. But from what I have seen, there are a number of C Dory 25's with transom cracks into the corners of the splash well.

Perhaps a better question is should the factory have done a general recall and repaired/sealed the openings? If this had been an automobile, I suspect that there would have been a recall.

Despite the above thread done in 2005: my 2006 Tom Cat 255 still had unsealed core. So what happens at the VP level does not always trickle down to the worker level.....
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