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Thread: CPES on 36 year old mahogany bottom planks affect taking up?

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    Default CPES on 36 year old mahogany bottom planks affect taking up?

    We are restoring Bolger's Shearwater shallow draft schooner built here in Essex by us in 1979-80. The boat held up well so long as it was in New England, but it went to California and 6 years in a San Diego marina was almost the end of her. Our son found her on Ebay and bought her (despite our warnings about what it would take to fix her up and own her.) He soon found the SF Bay area not to be the best place to have this work done and he shipped her back to us last winter.

    We have refastened the whole bottom - the electrolysis was incredible, replaced a couple of sections of garboard and recaulked, replaced all through hulls and all plumbing and wiring. Now we are faced with some decisions about how to protect the bottom when the boat goes back to California in a year or two. He has experienced teredo damage to the rudder of a day sailor he has been keeping at Redwood City marina and that woke us up to how real a problem this is and how fast damage can occur.

    Several people on this forum have recommended CPES on the bottom as a partial protection against worms, perhaps an extra bit of protection against old mahogany planks getting waterlogged, and as a sealer. Some have used both CPES and red lead. The bottom still has a lot of the original red lead on the bottom that we put on her, but there was no such thing as CPES during the 30 years that Brad was building boats, so this is a new technology to learn about. He has the following questions for those with experience in any similar situations:

    1. Will the CPES prevent the bottom from taking up when we put her back in the water after 2 1/2 years in a shed? We realize it might delay the swelling up a bit but can anyone say with any specifics how much it slows down the swelling up and whether the final result will be that the planks will return to their pre-haul dimensions? We assume we will want it to sit in the water without being sailed for weeks after having been out for so long, but we need to know if the CPES will prevent it from fully taking up again?

    2. Do we need to get all the old red lead off the bottom for the CPES to do its thing? The edges of the planks are bare and the new caulking will certainly draw the CPES into the seams, but any guesses on how it will work if we don't get to bare wood everywhere? Kind of hate to take that red lead that is still hard and tenaciously holding to the wood off if it isn't necessary. Our assumption is that we probably have to get it off but we would be interested in anyone's experience using CPES with some primer still in the wood.

    3. Any thoughts on using red lead on the bottom as a primer after the CPES? Do they work well together? Any issues we should be aware of?

    We know we could sheath the boat with copper, but frankly the pocketbook says no. We'd also like to get this boat back in the water before we are too old to go cruising on her with our son and his family.

    Any specifics much appreciated.
    Last edited by bstory; 04-03-2016 at 05:47 PM.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    1. No, the CPES will not prevent her from taking up again. It only soaks into the face grain about a 1/16 of an inch. It is moisture permeable, as basically is all epoxy. It will perhaps take a bit longer, but not to a degree that should bother you.

    2. Yes, you need to get down to bare wood if you want your CPES to be effective. If there is paint on the surface, you are just putting CPES over old bottom paint, which will prevent its penetrating and it won't do what you are paying it to do. A certain amount of old paint will remain in the grain and you can CPES over that with adequate results, but putting CPES over a coated surface is pointless.

    3. Putting red lead paint on top of CPES is a waste of paint. Period. It adds nothing to the job except a lot of unnecessary expense. It was an excellent cheap primer in its day, but it ain't cheap anymore. Red lead does nothing more to repel marine borers or rot than any good paint. It's "traditional" because it was what was available traditionally. There's no magic to it beyond that.

    4. Current practice in California these days is to use an epoxy barrier coat on top of CPES and then a good antifouling paint on top of that. The barrier coat serves as a mechanical marine borer barrier, but should be carefully applied to ensure no nooks or crannies the critters can find their way into. Within the last few years SF Bay has experienced a terredo explosion of epic proportions. The marine biologists are uncertain of what caused the sudden appearance of a breed of the buggers not seen hereabouts before, or at least in a long while. They consider that the recent drier weather, which means saltier water in the creeks and estuaries, cleaner water thanks to all sorts of environmental laws, and warmer water due to climate change may have created a favorable environment for some alien species of terredo that hitch-hiked into the area in some ship's ballast tanks... or was always here but not in sufficient numbers to make an impact. Coating a bottom with creosote used to work pretty well in the old days. Until somewhat recently, effective antifouling paint ensured no borers. However, when they outlawed antifouling paint containing tributyl tin oxide, arsenic, and other things that killed the critters (and in some places they are now outlawing even copper in bottom paint!) the stuff hasn't been much better at preventing borers and fouling than ordinary paint any more. (In most places in California you can hardly even find oil based paint anymore because that, too, has been outlawed.)

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    When you say "epoxy barrier coat," what exactly do you mean? A 2-part epoxy bottom primer like people use on fiberglass boats or something else?

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    I swear this is an honest question and not an attempt to start a flamewar, but if CPES won't stop the wood from "taking up" (i.e. absorbing moisture,) what is its purpose?

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by LittleJohn View Post
    I swear this is an honest question and not an attempt to start a flamewar, but if CPES won't stop the wood from "taking up" (i.e. absorbing moisture,) what is its purpose?
    "CPES" is a Clear Penetrating Epoxy Sealer. It's purpose is to serve as a sealer. It has nothing to do with stopping wood from swelling. Why would anybody want it to? (Aside from people who build plywood boats and don't really understand the whole process of traditional boatbuilding at all.) See: http://www.smithandcompany.org/CPES/index.html A "sealer" is a paint or other coating that is applied thin and soaks into the bare wood, forming a base for future coats to adhere to.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by Bob Cleek View Post
    "CPES" is a Clear Penetrating Epoxy Sealer. It's purpose is to serve as a sealer. It has nothing to do with stopping wood from swelling. Why would anybody want it to? (Aside from people who build plywood boats and don't really understand the whole process of traditional boatbuilding at all.) See: http://www.smithandcompany.org/CPES/index.html A "sealer" is a paint or other coating that is applied thin and soaks into the bare wood, forming a base for future coats to adhere to.
    Now I'm really confused. What is it sealing out (or in) if not water? And what is making the wood swell if not absorbed water?

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by bstory View Post
    When you say "epoxy barrier coat," what exactly do you mean? A 2-part epoxy bottom primer like people use on fiberglass boats or something else?
    I mean epoxy barrier coat, exactly.



    http://www.boatersland.com/barrierko...FRSUfgod2y4C6Q

    Every marine paint company sells their own version of the stuff. It's made to coat polyester fiberglass hulls because it is more impermeable than polyester laid up glass. It goes on like paint and lays down flat. Some wooden boat owners use it to create a mechanical barrier to borers.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by LittleJohn View Post
    Now I'm really confused. What is it sealing out (or in) if not water? And what is making the wood swell if not absorbed water?
    It isn't sealing out anything and wood will swell and shrink with changes in the ambient humidity no matter what. The problem is that you don't understand the terms. "Sealer" doesn't seal out water. "Sealer" (as opposed to "undercoat" which is another thing entirely) is often also referred to as a "primer" (which is distinct from undercoat, but few "weekend warriors" seem to know the difference if the posts in here are any indication.) "Sealer," being thinner than paint or varnish, more readily soaks into the surface of the wood and forms a base to which the subsequent coats of paint or varnish adhere. (Paint and varnish applied to bare wood without being thinned just stick to the top layer of the wood and that's it.) Sealers do inhibit immediate moisture absorbtion, but they do not "seal out" water and the wood swells no differently, albeit sometimes more slowly, than it always does.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    And here we see the difference between English and Americlish again. Paint comes in three layers (normally). The first coat, that we call primer (prime = first) that you call sealer provides the good key to the wood, allowing the subsequent layers to adhere. This is why you thin the primer coat of varnish so that it soaks in and gets a good grip.
    Then comes undercoat which builds up the film thickness, opacity and water resistance.
    Finally the gloss or top coat, which gives the final colour and shine.

    This system will vary for some modern paints, or paint over GRP including GRP sheathed wood.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by Bob Cleek View Post
    It is moisture permeable, as basically is all epoxy.
    eh?
    Simpler is better, except when complicated looks really cool.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    All epoxy is permeable, just as virtually all materials are water soluble. Epoxies can be formulated to either be quite permeable, or among the most vapor-proof and moisture-proof barriers available.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    For about twenty years I used epoxy as a waterproof base coat part of a two coat paint system in my kennel/lab with a two part urethane top coat for UV resistance. It worked exceptionally well. Until recently it was difficult and expensive to source a urethane system that could build adequate thickness without using an epoxy base first. Only in the last three years have I gotten away from the epoxy base and now use a system of two coats of two part urethane. My floor system is still epoxy over epoxy/silica over concrete. I never had any problems with moisture transfer in or out of the concrete walls or floor through the epoxy.
    Simpler is better, except when complicated looks really cool.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by Paul Pless View Post
    For about twenty years I used epoxy as a waterproof base coat part of a two coat paint system in my kennel/lab with a two part urethane top coat for UV resistance. It worked exceptionally well. Until recently it was difficult and expensive to source a urethane system that could build adequate thickness without using an epoxy base first. Only in the last three years have I gotten away from the epoxy base and now use a system of two coats of two part urethane. My floor system is still epoxy over epoxy/silica over concrete. I never had any problems with moisture transfer in or out of the concrete walls or floor through the epoxy.
    Epoxy "garage floor" coatings are formulated to be far less permeable for the reasons you stated. Moisture, being lazy, will take the path of least resistance. A barrier coat on concrete will induce the moisture to seek some other way out, unless, of course, the pressure of water is greater than the barrier. Even so, in that application, there will be moisture transfer. You didn't have any problems because you didn't notice it. It would take a lot of it to be noticeable.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by Bob Cleek View Post
    Epoxy "garage floor" coatings are formulated to be far less permeable for the reasons you stated. Moisture, being lazy, will take the path of least resistance. A barrier coat on concrete will induce the moisture to seek some other way out, unless, of course, the pressure of water is greater than the barrier. Even so, in that application, there will be moisture transfer. You didn't have any problems because you didn't notice it. It would take a lot of it to be noticeable.
    I use about four thousand gallons of water everyday in our washdown.
    Simpler is better, except when complicated looks really cool.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by Paul Pless View Post
    I use about four thousand gallons of water everyday in our washdown.
    So, how wet is the concrete slab under the paint?
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    I've concluded that its dry for three reasons:
    • first, the coatings have not failed (lifted) because of water transfer from below - there have been coating failure from impact and from abrassion
    • secondly, we have during remodeling or to install a new piece of equipment, ground through the coating to reach the slab below or the wall behind and it has always been dry
    • thirdly, there is no evidence of weeping on the edges of the slab or walls below ground level.
    Simpler is better, except when complicated looks really cool.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    I used it on ever sliver of Sarah and had no problems whatsoever with her taking up. Some places I might have gone a little overboard, but more on that in another thread.

    What Cleek said above.

    It's purpose is to bind the paint to the wood with a chemical bond vs a mechanical bond.

    It also makes the wood fiber less tasty to worms - if you have that problem in California.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by Paul Pless View Post
    I've concluded that its dry for three reasons:
    • first, the coatings have not failed (lifted) because of water transfer from below - there have been coating failure from impact and from abrassion
    • secondly, we have during remodeling or to install a new piece of equipment, ground through the coating to reach the slab below or the wall behind and it has always been dry
    • thirdly, there is no evidence of weeping on the edges of the slab or walls below ground level.
    Then it sounds like it's doing what you want it to do and it's likely very low permeability epoxy.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    wow, glad i read all this. I have a beutiful Chris Craft Connie. she is 45 ft, 1960 and is the 16th of 56 made. Not many around. So i have to redo the entire bottem so i will use CPES on her first when i scrape and sand the bttm. Now what do you use to dilute the first coat of this. no one mentioned if you do or and what with. thanks

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Just re-starting this thread as it seems quite relevant to the cutter I'm building that will be carvel planked with Alaskan yellow cedar. Does anyone know if applying thinned "traditional" epoxies such as West System or G/Flex will result in similar worm protection properties, while still allowing the planks to "take up" and swell the seams shut? If so, it seems to me that the latter may be significantly less costly.

    Thanks!

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by keck314 View Post
    Just re-starting this thread as it seems quite relevant to the cutter I'm building that will be carvel planked with Alaskan yellow cedar. Does anyone know if applying thinned "traditional" epoxies such as West System or G/Flex will result in similar worm protection properties, while still allowing the planks to "take up" and swell the seams shut? If so, it seems to me that the latter may be significantly less costly.

    Thanks!
    CEPS is mo betta than thinned WEST for what you seek.
    Thinning WEST is a no no .

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by LittleJohn View Post
    I swear this is an honest question and not an attempt to start a flamewar, but if CPES won't stop the wood from "taking up" (i.e. absorbing moisture,) what is its purpose?
    It is a commercial product - designed to extract money from customers.

    Lures are designed to catch fishermen - not fish.
    Someday, I'm going to settle down and be a grumpy old man.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by P.I. Stazzer-Newt View Post
    It is a commercial product - designed to extract money from customers.

    Lures are designed to catch fishermen - not fish.
    Precisely!! Well expressed P.I.

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Quote Originally Posted by wizbang 13 View Post
    CEPS is mo betta than thinned WEST for what you seek.
    Thinning WEST is a no no .
    Better how? I'm not doubting, I just want to understand what it is about CPES that makes it superior for this type of application. I've used thinned West System before, to seal the plywood hull of my Nutshell pram. That seems to be holding up fine, but of course it doesn't need to interact with the water the way a carvel hull does!

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    Default Re: CPES on 36 year old mahogany bottom planks affect taking up?

    Thinning WEST is a no no .
    This is simply not true. However, there are side effects to consider whenever you thin any epoxy resin, and don't buy the BS hype that CPES is something so different. There is no magic going on here.

    http://epoxyworks.com/index.php/thin...e=thinning+wes

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