Pre-coat strakes on Passagemaker?


Am starting my Passagemaker take-apart build.  Previously built a Skerry successfully (at least, it floats. . . )

The PMD manual says to pre-coat all the wood parts with a thin coat of epoxy, including the strakes; before wiring it together.  When I built the Skerry, the instructions did not say to do this.  First I wired it up, then tacked it together and removed the wires, then coated everything with epoxy.  Was wondering why they are different?

I'm inclined not to follow the directions and instead only coat with epoxy later in the process (as I did with the Skerry), mostly because pre-coating would fill up the pre-drilled holes that I want to poke the wires through.  I think it would also make the strakes stiffer but the bends aren't that sharp in this hull so I don't think that will be a big problem.

Would appreciate any thoughts or suggestions on the best way to do things here.


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RE: Pre-coat strakes on Passagemaker?

Looking back at the photos from our PMD build, we did coat the strakes.  I seem to recall that I went around and poked something through the wire holes after the epoxy had gotten a bit tacky so that the holes wouldn't close up.



RE: Pre-coat strakes on Passagemaker?

I will be going another route.  I will be saturating the planks on my PM with penetrating epoxy, both inside and out.  Whether I do this while the planks or laying flat on the bench or after I've glued the laps together, I haven't worked out yet. 

Two issues are full penetration, which I can only get with doing them before assembly.  The second is does the penetrating epoxy blush or otherwise interfere with bonding of the planks so they'd need to be sanded/wiped before stitching the boat together.  Also, will that affect making the necessary bends.  Now that I'm writing this, I may just stitch the laps together or do the full bead, then coat the entire boat once it's boat-shaped.

I had SERIOUS issues with water penetration on my EP over the years, so I basically want to turn my PM into a floating piece of wood-colored plastic. 

Then I'm back to do I need to sand/wipe the boat down before I apply the glass. Everything on boats is a trade-off.  Sigh...

RE: Pre-coat strakes on Passagemaker?

   I tried CPES on a boat repair project some time ago, and was not impressed.  It's just regular resin, highly diluted with solvents, which evaporate out.  Read the SDS, it's more than half solvent.  It was carried pretty deep into deteriorated wood, but didn't seem to get very far into the solid areas.  I can't say that the deteriorated wood (cracked/some rot) really firmed up to be as hard as sound wood. That's because so much of the volume of goo was solvents that just evaporated.  It was white oak ribs that I was repairing.  I really should have just sistered them and cut out the bad parts. The two CLC boats I've done so far were both with the MAS system with slow hardener, which gave me the time to make sure I rolled out and coated everything.  I used more epoxy than really needed, but it made sure I never sanded through the coating.  Neither lives in the water, so I can't speak to that kind of exposure, but the Sassafras is going strong 12 years later.  The Skerry is nearly new.  Just my experience.

RE: Pre-coat strakes on Passagemaker?

Interesting feedback.  I have made numerous workbenches and even a portable picnic table using 3/4" plywood and soaked with marine grade penetrating epoxy.  They have been pretty much bullet-proof.  This will be on 1/4"/6mm so should soak completely through if applied from both sides.

I might check into just diluting the MAS epoxy I already have to see if that produces a viable penetrating epoxy. 

I always use slow because mistakes with fast epoxy are pretty permanent.  I'd rather wait until the next day and make sure things are right than worry about being fast.



RE: Pre-coat strakes on Passagemaker?

Thanks all for the comments and feedback.  I decided to pre-coat the 6" of wood on either side of the puzzle joints, to make sure those are nice and saturated and strong for assembly.  I did not pre-coat the rest of the planks / hull; I'll do that post-assembly like I did for the skerry.


RE: Pre-coat strakes on Passagemaker?

CaptainSkully wrote:

“This will be on 1/4"/6mm so should soak completely through if applied from both sides.”

Cap’t, I’m curious whether you’ve ever cross-sectioned plywood treated with penetrating epoxy? See if it really does cross the glue lines?

I’ve always believed (never tested penetration this way) it doesn’t, instead being restricted to the surface or at best the first underlying veneer, even when coated on both sides.

Kind of like testing epoxy bond strength with scraps glued together then subjected to sufficient stresses to point of bond failure... see whether the bond is stronger than the materials on either side?

I’m not disagreeing with you mind, just seeking to verify what you suggest is happening is really happening.

RE: Pre-coat strakes on Passagemaker?

That's actually a great point.  Thanks for pointing that out.  I hadn't thought about it that way.  I have only used it with construction grade 3/4" (23/32") AC plywood so the surface veneers are much thicker.  The penetrating epoxy does saturate those, which creates a waterproof envelope within the plywood that is bulletproof.  I also pay special attention to the cut edges, which it soaks into. 

Even if it only soaks into the two outside plys of the 5-ply marine grade 1/4" plywood, hopefully that's better protection than pre-coating regular epoxy that's just floating on the surface.  Once again, I will be saturating the cut edges, so that should soak into the middle plys at least an 1/8" or more. 

I'm just trying to prevent the extent of the water damage that I've seen on my Eastport Pram, which is unfortunately now just a playground feature in the back yard. 

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