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unfix8r

Epoxy over treated lumber...okay to proceed?

20 posts in this topic

Hi everyone,

 

NOOB questions here:

 

After building up some cradles for my Flying Dutchman for a perfect fit, with lots of layers, balsa coring, Baltic Cloth, and time, it's time to mount them to the trailer... I'm using treated 2x10's to match the curve of the bottom of the cradle. I'm going to glue them to the bottom of the cradles with epoxy + cabosil, and use 6' fiberglass tape as a fillet.

 

I'm planning on epoxying the the boards for water resistance, then painting the whole shooting match for looks.

 

The questions: Is there any reaction I can expect/ avoid using treated lumber and epoxy? Will it inhibit the reaction?

post-17196-059540900 1330716115_thumb.jpg

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The water content is always really HIGH so i gotta wonder how well and how long it would stay on :)

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The water content is always really HIGH so i gotta wonder how well and how long it would stay on :)

 

How long the epoxy would stay on... because of water content? I don't think that'll be an issue, but maybe I'm wrong about that.

 

I'm more worried about a chemical reaction between the epoxy resin and the (copper?) wood treatment.

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Problem is fresh treated lumber is wet, really wet. So if it's old and dry then you should be fine. Otherwise, find something dry.

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With treated wood..that is for weather..you really don't need to protect it any further..the epoxy may keep moisture in and not let the wood air out..as most isn't kiln dried...most that I have seen just mount the wood by itself on the trailer...etc... And cover it with some kind of carpet to protect the boat from scratching...having it wide enough to fold under the back side of the wood and nailing or stapling..

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With treated wood..that is for weather..you really don't need to protect it any further..the epoxy may keep moisture in and not let the wood air out..as most isn't kiln dried...most that I have seen just mount the wood by itself on the trailer...etc... And cover it with some kind of carpet to protect the boat from scratching...having it wide enough to fold under the back side of the wood and nailing or stapling..

 

So then how should I attach the boards to the cradles? Just do the epoxy thing to attach it to the cradles? Don't get me wrong, I'm lazy as the next guy, but want to have this last a long time. Should I paint the boards? I'm going to be launching the boat with the trailer 90% of the time. Will salt water "kill" the treated wood?

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With treated wood..that is for weather..you really don't need to protect it any further..the epoxy may keep moisture in and not let the wood air out..as most isn't kiln dried...most that I have seen just mount the wood by itself on the trailer...etc... And cover it with some kind of carpet to protect the boat from scratching...having it wide enough to fold under the back side of the wood and nailing or stapling..

 

So then how should I attach the boards to the cradles? Just do the epoxy thing to attach it to the cradles? Don't get me wrong, I'm lazy as the next guy, but want to have this last a long time. Should I paint the boards? I'm going to be launching the boat with the trailer 90% of the time. Will salt water "kill" the treated wood?

 

As the moisture content of the timber changes, it WILL change shape...

 

Are you trying to make the timbers match the curve of the cradle?

Like all the way across UNDER curved pieces of the cradle?

Or are you just trying to get the curved pieces attached to the timbers where they cross each other?

 

Pix or sketches would help

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With treated wood..that is for weather..you really don't need to protect it any further..the epoxy may keep moisture in and not let the wood air out..as most isn't kiln dried...most that I have seen just mount the wood by itself on the trailer...etc... And cover it with some kind of carpet to protect the boat from scratching...having it wide enough to fold under the back side of the wood and nailing or stapling..

 

So then how should I attach the boards to the cradles? Just do the epoxy thing to attach it to the cradles? Don't get me wrong, I'm lazy as the next guy, but want to have this last a long time. Should I paint the boards? I'm going to be launching the boat with the trailer 90% of the time. Will salt water "kill" the treated wood?

 

As the moisture content of the timber changes, it WILL change shape...

 

Are you trying to make the timbers match the curve of the cradle?

Like all the way across UNDER curved pieces of the cradle?

Or are you just trying to get the curved pieces attached to the timbers where they cross each other?

 

Pix or sketches would help

 

You know, I'd planned to have them run the length of the cradle, matching it all the way, and perpendicular to the trailer tongue, but now you've got me thinking I'll run them parallel to the trailer tongue, and build up a "pad" under where they'll support the cradles. The boat weighs less than 500#, so I'm sure that the cradles can support the weight without distortion. I'm no engineer, but your question actually helped with the design!

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With treated wood..that is for weather..you really don't need to protect it any further..the epoxy may keep moisture in and not let the wood air out..as most isn't kiln dried...most that I have seen just mount the wood by itself on the trailer...etc... And cover it with some kind of carpet to protect the boat from scratching...having it wide enough to fold under the back side of the wood and nailing or stapling..

 

So then how should I attach the boards to the cradles? Just do the epoxy thing to attach it to the cradles? Don't get me wrong, I'm lazy as the next guy, but want to have this last a long time. Should I paint the boards? I'm going to be launching the boat with the trailer 90% of the time. Will salt water "kill" the treated wood?

 

As the moisture content of the timber changes, it WILL change shape...

 

Are you trying to make the timbers match the curve of the cradle?

Like all the way across UNDER curved pieces of the cradle?

Or are you just trying to get the curved pieces attached to the timbers where they cross each other?

 

Pix or sketches would help

 

You know, I'd planned to have them run the length of the cradle, matching it all the way, and perpendicular to the trailer tongue, but now you've got me thinking I'll run them parallel to the trailer tongue, and build up a "pad" under where they'll support the cradles. The boat weighs less than 500#, so I'm sure that the cradles can support the weight without distortion. I'm no engineer, but your question actually helped with the design!

 

Cool!

 

I'll pass that on to the WLYDO accounting department.

 

Now - where they attach to each other, will the balsa core survive compression loads?

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Gougeon Bros, I believe, suggest not encapsulating solid wood that has more than 3/4" - 1" on a side: too much movement, the epoxy will crack.

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What they used to do for the ULDB s they were hoist launched..some had carpet covered pads on each stantion..some had like 2 x6 boards go parallel with the trailer attaching to all of the stations on the one side...but I don't know how this would hold up ramp launching maybe if you could take a road trip to a local marina and see what the power boat trailers are using..they may ave some completely different set up for those boats because now you do have to handle with submerging the wood into saLt water...or maybe get some ideas from going to trailer mfg web sites...best of luck..

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Check with your local lumber yard for KDAT/kiln dried after treatment lumber. Widely available.

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With treated wood..that is for weather..you really don't need to protect it any further..the epoxy may keep moisture in and not let the wood air out..as most isn't kiln dried...most that I have seen just mount the wood by itself on the trailer...etc... And cover it with some kind of carpet to protect the boat from scratching...having it wide enough to fold under the back side of the wood and nailing or stapling..

 

So then how should I attach the boards to the cradles? Just do the epoxy thing to attach it to the cradles? Don't get me wrong, I'm lazy as the next guy, but want to have this last a long time. Should I paint the boards? I'm going to be launching the boat with the trailer 90% of the time. Will salt water "kill" the treated wood?

 

As the moisture content of the timber changes, it WILL change shape...

 

Are you trying to make the timbers match the curve of the cradle?

Like all the way across UNDER curved pieces of the cradle?

Or are you just trying to get the curved pieces attached to the timbers where they cross each other?

 

Pix or sketches would help

 

You know, I'd planned to have them run the length of the cradle, matching it all the way, and perpendicular to the trailer tongue, but now you've got me thinking I'll run them parallel to the trailer tongue, and build up a "pad" under where they'll support the cradles. The boat weighs less than 500#, so I'm sure that the cradles can support the weight without distortion. I'm no engineer, but your question actually helped with the design!

 

Cool!

 

I'll pass that on to the WLYDO accounting department.

 

Now - where they attach to each other, will the balsa core survive compression loads?

 

You know I'm going to put a wood pad, probably plywood,between the longitudinal board and where the cradle is. I figure a square foot or so each, and the pad will dissipate the force enough. I mean, this is a light dinghy, 400# all up, and maybe 100# when I travel for regattas on the West Coast. I'm finidign that it's the attachment at 90 degrees is the hard part of trailers!

 

Then it's on to grinding down the rust and painting the trailer. I'm thinking gold. :)

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Read that Gougeon had tested and found good adhesion with borate treated wood. options are 1 1/8" ply or thick OSB.

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If the wood is the most common type - CCA pressure treated - the issue is the moisture content of the wood. Not only does wet wood make for a weak bondline, it is also very dynamic and will move and twist as it dries. The copper component is not the issue.

 

Given that its a trailer and will not be submerged for long periods I would advise against using the treated lumber use untreated lumber, encapsulate the parts with a couple coats of epoxy and bond the beds to the wood with G/flex 655. Everything should get painted as the last step for longevity.

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If the wood is the most common type - CCA pressure treated - the issue is the moisture content of the wood. Not only does wet wood make for a weak bondline, it is also very dynamic and will move and twist as it dries. The copper component is not the issue.

 

Given that its a trailer and will not be submerged for long periods I would advise against using the treated lumber use untreated lumber, encapsulate the parts with a couple coats of epoxy and bond the beds to the wood with G/flex 655. Everything should get painted as the last step for longevity.

 

I think what I'll be doing is epoxying in a pad, say 1 foot x 1 foot, that will match the cradle, and then use the treated 2 x 10's to mount the pads to the trailer, so the 2x10's will run the length of the trailer, and the cradles will rest on them. So I'm not going to epoxy the 2 x10 stringers; I'm sure for the number of times they'll be submerged, or even wet, won't affect much at all. I'll continue to monitor of the cradles are getting warped at all every so often by lifting the boat and looking for fit, but again, it's not that heavy a boat. Thanks for the input... I figured if you cover wood with epoxy, the moisture content just stays the same, kind of like suspended animation.

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You probably don't need to get too high tech with the mounting.

 

Definitely make sure they fit well and are fixed correctly on the trailer or you will get hard spots in your hull. Rather than carpet, I'd recommend the plastic 70's door mats that look like fake grass. They dry out much quicker. Especially necessary if your hull is painted.

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Those 2x10's will last forever just as they are. We use 4x6 posts on our small dock on the sound and they last a good 10 to 15 years, and they get submerged twice a day or hours at a time.

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