Cape Dory 330 seacock backing

[Bob McCracken]

I am replacing two of my three seacocks, on my Cape Dory 330. They have fallen victim to a bit of electrolysis. While doing this I want to replace the backing between the thru hull and seacock. The original is teak plywood. I also noted in the manual that it shows the using of plywood. I plan to use sold teak instead. Cut to confirm with the shape of the hull. Have any of you had experiance with this? Or know of any reason for not using solid teak.



raven@net-magic.net

[Joe]

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I am replacing two of my three seacocks, on my Cape Dory 330. They have fallen victim to a bit of electrolysis. While doing this I want to replace the backing between the thru hull and seacock. The original is teak plywood. I also noted in the manual that it shows the using of plywood. I plan to use sold teak instead. Cut to confirm with the shape of the hull. Have any of you had experiance with this? Or know of any reason for not using solid teak.

I think you either don't have a 330 or you need to count more carefully. A CD 330 has six seacocks, not three. There is one in the port lazarette for pump-out, two under the galley sink (one for the sink and the other for the engine salt-water cooling intake) and three under the head sink -- sink out, head in, head out.

Use the plywood, not teak. There are powerful reasons for same.

Joe




tgjournal@gestalt.org

[zeida]

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I would like to know the powerful reasons for using the teak plywood vs. solid teak when replacing the backing for the seacocks in the CD-33's. Mine (the teak plywood backings) are gradually delaminating, and have thought of precisely replacing them with solid teak. Is the plywood more absorbent? -they do get wet when the things leak!!! Are they more bonding-friendly? Curious in Miami.
Zeida



zcecil@attglobal.net

[Russell]

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[John R.]

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I am replacing two of my three seacocks, on my Cape Dory 330. They have fallen victim to a bit of electrolysis. While doing this I want to replace the backing between the thru hull and seacock. The original is teak plywood. I also noted in the manual that it shows the using of plywood. I plan to use sold teak instead. Cut to confirm with the shape of the hull. Have any of you had experiance with this? Or know of any reason for not using solid teak.

Bob;
Over the years I've used both. First of all the only plywood to use is "marine grade" (manufactured without voids and has more plys). It should be epoxy coated with at least two coats. I prefer West System for that purpose. I've used teak blocks as well being careful in the woods selection to be sure it is a tight straight grain without flaws.
If you don't coat the wood with epoxy sooner or later the wood is going to degrade from electrolysis, period! These days I have switched to using fiberglass 3/8" - 1/2" thick. I either make up a panel out of matt fabric and epoxy or I try and find a flat panel already made at a boatyard or salvage place, not a cored panel. Sometimes you can find old runabout hulls that you can cut up. If it isn't thick enough just laminate a couple of pieces together with epoxy and clamp it together.

From the panels just use a hole saw the diameter of the backing plate size you need. After that use another hole saw the size of the thru hull and run it through the backing plate you just cut out with the other hole saw. Use the same bit guide hole. Use a disc sander (bench type best) or a belt sander if you can control it and bevel the edge of the backing plate. You can seal the edge of the backing plate with epoxy or polyurethane paint if you don't want the raw glass edge. You should seal the inner edge that the thru hull passes through with epoxy.

They make a very nice plate with the gel coated surface and look professional and are stronger than hell. Far better than any wood.You won't have to replace them in 5-10 years.

[Chris Reinke - CD330 Inni]

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Bob - I would like to offer my limited understanding of "marine" plywood for your consideration. Although I do like the ideas presented by John.

The term "marine" plywood can have many different meanings depending on who you ask (where you buy it). The only true designation for "marine" plywood is offered by the American Plywood Association (yes it does actually exist). The APA designation only covers plywood manufactured in the United States. The APA "Marine" Grade plywood is available in a wide range of thickness’ and number of ply. The APA designation refers to panels constructed using tested procedures and consistent quality. The "marine" panels use a specific waterproof glue and gluing procedure. The waterproof glue ensures the structural integrity of the panel even if the wood remains submerged for an extended period of time. The APA testing includes a load test, ply sheering test and a boiling test. If you decide to use a ‘marine" grade plywood I would recommend you confirm the APA "marine" seal is stamped on the panel.

FYI - International cargo container utilize a 2" thick 15 to 19 ply marine grade panels which come in 3'x5' panels and weight about 150 pounds (cost $250 each). Marine plywood is also available constructed out of tropical hardwoods such as Apitong (very strong, very heavy, and VERY VERY expensive)

Good Luck,
Chris Reinke

I am replacing two of my three seacocks, on my Cape Dory 330. They have fallen victim to a bit of electrolysis. While doing this I want to replace the backing between the thru hull and seacock. The original is teak plywood. I also noted in the manual that it shows the using of plywood. I plan to use sold teak instead. Cut to confirm with the shape of the hull. Have any of you had experiance with this? Or know of any reason for not using solid teak.