1960 Chris Craft sportsman restoration project

Hmmm.... "arm chair professionals"..

This site is peopled by boating enthusiasts of the best kind.
Opinions on approach can vary- sometimes sharply, but don't let this put you off.
You will be hard pressed to find another site where such good information can be found on such a diverse range of topics on things boating..

On CPES epoxies-

I have never once in my life used any penetrating epoxy product and wouldn't ever consider the use of these products.
Why not?
Well, if the part is in good condition and it is appropriate to encapsulate, I want to get the job done. which means pure epoxy resin lain on till full saturation of the surface occurs.
If the part is rotten or damaged- I replace it or scarf in new wood as required.

Every so often I get to see the results of CPES in use when I have to do follow up repairs on failed restoration projects. I find spongy rotten wood which has a bit of a gloss to it that covers real damage to structures.
Owners claim to have tried to stop the rot by carefully dabbing on penetrating epoxy over the years as the problem just continues to grow..

For any lovers of the CPES approach- next time duty calls and you reach for this product, just use some laminating resin. The epoxy will fully toughen the bit of soft wood to extent possible in any epoxy approach. If the damage is deeper than can be addressed by resin- fix it correctly by scarfs or replacement.

 

I do find it occasionally necessary to decrease epoxy viscosity Thomas, but would not use a solvent based product, particularly the absurd concoction of Smith Brothers. It quite literally is 70% solvents, some directly contradicting each other and 30% epoxy, of which they charge $130 - $150 a gallon for! The epoxy molecule is so badly distorted with these solvent levels, it's useless.

My bad for mistaking West System for West Marine (by personal marine supply bible ).

Again, penetration isn't what's important in regard to waterproofing, coating quality is. If penetration is desired for some reason, the hot on hot method works better and produces real waterproof results.

 

Use pure epoxy- three coats minimum paying particular attention to the end grain which will need to be coated repeatably till no more resin is drawn into the pores of the ply core.

No epoxy- CPES or otherwise will saturate rotten ply to the extent to save it.
This is a judgement call on repair approach. If possible- take the FULLY dry damaged ply section and break up the lower edge by working a pallet knife between the laminates- wet out fully with pure laminating epoxy, squeeze repeatably to pull the epoxy into the the ply. Repeat with mayonnaise consistency epoxy mix of resin and colloidal silica. Clamp up repair area.

The single most important repair consideration is in attending to the leaks which caused the problem...

Coat three times with pure epoxy resin as above- paying attention to end grain...

 

Read post #62.

 

Ya- me too though I never go beyond heating resin..

 

There are non-solvent diluents that can be used, but you really have to have a clue chemically, about what you're doing. The same is true of solvents, which can be used as well, but I see no need to dilute past 10% - 15% and again you have to have a clue what you're doing to the molecule. All of the physical properties drop so dramatically after 10% - 12%, that further reduction, just isn't worth the trouble, considering what you get as a cured product.

Why some restorers just refuse to keep up has always bothered me, but the same is true in every industry. I know several automotive mechanics that once were really good, but haven't kept up and now really aren't good for much on a new car. I'm really glad doctors tend to keep pace, or we'd still be using cat gut and steel scalpels, instead of cyanoacetate and lasers. Every industry has this problem, old farts (like me) refusing to accept test results, advances and other "changes" to their way of doing things. Maybe it's a comfort level thing, I don't know, but one thing I do know is "change is the most essential element of all existence". Other wise the dinosaurs would still be here.

 

Thanks Par

 

Just found this on "Wooden Boat" forum.

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Torna12-27-2010, 06:00 AM
Since you're just dealing with structural ply and the act of sealing isn't itself structural you might just employ epoxy and a hairdryer or other heat gun.
Heat up the plywood area with hairdryer.
Apply epoxy. As the epoxy warms it will become very liquid and penetrate rapidly.
Continue to play the wet epoxy with hairdryer - epoxy will become the viscosity of water and penetrate very rapidly.
After just a few minutes of this, epoxy will begin to set (you won't be able to blow it around with hairdryer).
Toss a cozy over it and 20 mins later it's all set.

Others may know better, but I wouldn't think that this super accelerated cure produces full-strength joints; I wouldn't use it structurally. But for just end grain penetration (of structural ply) it should be fine.

-leif

 

When I was building my decks and cabin top I thought it a good idea to apply a seal coat to the plywood. This wasn't to prevent rot, this ply was new, rather it was to seal the wood so that a subsequent coat(s) of general purpose resin wouldn't soak in creating resin starved laminations and coatings.

Looking back I would have used general purpose resin for all the coats.

But I also fell into the "thin resin" trap. Fortunately I get my resin from System Three and they sell a product called Clear Coat Resin. This thin resin is 100% solids according to System Three. I'm no chemist but I do have a nose. I can't smell any solvents. It's about 1/2 the viscosity of their General Purpose Resin. Links to the technical data sheets are below.

If you really need a thin resin it's a good product. The question is "Do you really need a thin resin at all?"

http://www.systemthree.com/reslibrary/tds/Clear_Coat_TDS.pdf
http://www.systemthree.com/reslibrary/tds/SYS3_TDS.pdf

MIA

 

Of the commonly available brands Raka has the least viscosity, right out of the container. They're 100% solids and use modifiers, rather than solvents to thin the resin, which is the way you're suppose to do it. There are dray backs to thin resin, one being it requires more goo to fill weave.

Using a heat gun or hair drier, is the wrong way to gain penetration, as described above. It'll work, but it'll also out gas like a ***** too. Hot resin on a cold substrate, is a guarantee for out gassing bubbles.

The hot on hot method works by simple physics and you don't have to wave a heat gun over the work trying to "blow" goo into end grain or what ever. Heat the substrate, which should be raw wood (other wise you're wasting your time). You can heat it how ever you like. I'll take the part outside and leave it in the hot Florida sun for a few hours. A space heater works too or if you have nothing better to do, waving a heat gun (you'll make a career out of it using a hair drier) over the substrate. Once you're sure the substrate is hotter then surrounding temperatures, heat the epoxy too and a microwave works well for this. 100 degrees is all you need and naturally slow or super slow hardener. Remove the heat from the substrate and wait a few minutes, so it begins to cool, then apply the epoxy. On some woods, it'll all but disappear as it's literally sucked into the wood, from the cooling (contracting air pockets in the wood's cells) substrate. This trick only applies to raw wood, because once you've applied epoxy, the pores are sealed and this trick doesn't work any more.

 

Ok...ok...ok Enough. This thread I started to share my restoration project. It has since been hijacked... Lets get back to the original purpose for this thread. I have finished the bottom of my Chris and will be getting the trailer ready. Flipping it back over will be next. It's been about 16 months since I flipped it. Here are some pics of the re-planked bottom. Take a look...

 

It looks pretty nice to me....