The Rot Doctor


Subject: 22' CC Sportsman Resto Question
Date: Sun, 27 Jun 1999

Hey Doc, First of all, I am sold on the CPES! I have scanned the questions here on the site hoping mine would not appear redundant. I do have some specifics, and if these have been answered on the Q&A section, I do apologize and let me know. I did find a good Q&A regarding encapsulating wood via Bob C. and from what I gathered from this post and one other, that encapsulating is not equal 100% rot resistance. The advantage of CPES is that it does allow the boat to breathe thus letting moisture pass in and out without being trapped and eventually causing rot.

This is true, as long as you do not use more than a couple of coats of CPES. Build it up too much, and you have epoxy saturated wood. On the other hand, CPES penetrates so well that having all deteriorated wood epoxy saturated may not be such a bad thing. This more or less what we are doing in some areas of our old tug, DELTA, and so far so good.

Currently, I have purchased a late 40's 22' Chris Craft Sportsman that I will be using as a pattern boat. Any wood I can salvage I will, but most is rotten to the touch, fortunately the boat is intact. Ok, with this in mind, here are my questions: 1) I am going pattern and replace all the frames and gussets probably using Mahogany for the frames and Fir for the gussets. Should I put 2 coats everywhere on the wood, and then again after fastening.

After the wood is cut, trimmed and ready to install, one good surface coating of CPES would be fine, add then two coatings of CPES on all edge and end-grain areas. These are the areas where the rot fungi generally get their grip and are most in need of protection. I personally would also recommend that as each hole is drilled for the fastening, I would dap with a bit of CPES. This will sink into the hole and give that wood protection as well. I don't believe additional coats after fastening would add much, except on planked areas where the CPES would be able to penetrate into the cracks between the planks -- that would be beneficial.

I had planned on using West for glueing (and laminating strips for cold molding) before I heard of CPES. Is West compatible with CPES? (Taboo question?)

Naw, not taboo. West products are good, just different than ours. All West epoxies are completely compatible with ours. Feel free to use them.

2) I am also going to cold-mold the entire boat...4 layers on the bottom, 3 layers on the freeboard. Again, should all strips be CPES'd prior to glueing to one another?

No, don't use CPES before glueing. Use it after glueing and sanding clean for cover coat application. Just brush it on, one coat will be fine.

And what of the outside of the outer skin? If I apply CPES to the outer skin (especially above the waterline) will the typical filler stains used on these boats work or should I not CPES the outside of the outer skin (...i.e. Wood soaked with CPES, Stain, Sealer, Varnish).

Here things get a bit tricky. CPES is a perfect undercoating for final finishes. It grips the wood better than anything else and all final coatings adhere to it very well. We favor polyurethanes, believing that they get the best molecular grip with the CPES-treated wood.

That said, we now get to stains. Oil based stains and CPES are basically incompatible. If the oil-stain goes on first, the oil base interferes with the penetration of the CPES, and if the CPES goes on first it interferes with the penetration of the stain. For this reason we say that if you're going to use a stain USE A WATER-BASED STAIN. They are available -- look in woodworking stores. Apply the stain and allow it a day or so to dry, and THEN go back with the CPES. It will lock the stain to the wood and give you that good base I was writing about for all your final coatings. We always suggest you do a little test patch first on a scrap piece of wood to make sure that you get the kook you are after. Remember that CPES highlights grain and wood structure and will add depth to the stain. It can look beautiful.

So what you end up with is: Water-based stain / CPES / final coatings. A filler is not necessary because CPES serves that function. You very lightly sand the wood again after the CPES if you want to knock off the wood fiber tops. It is not necessary to thin-down the first coat of final coating. Just put it on full strength, or whatever flows smoothly. You can dilute it with whatever to increase the good flow -- nothing is incompatible with a cured CPES coating.

Thanks...any suggestions would be helpful. H.K.

Hey! Have fun. It sounds like it could be a happy project, although a lot of work. The hull forms on the old Chris boats were sweet and easy to run. Give us a picture or two if you happen to think about it. Come on back if you have additional questions.