WD12 - what was that crack sound?!?!

Well, the construction of my wife's Wood Duck 12 Hybrid is well under way.  I'm building from plans, and things seemed to be going a bit too well.  Unfortunately I was correct!

I'm in the process of stitching the bottom together, and all I had left was the stern.  I had the inner layer soaked pretty well, and was simply flexing the two ends together to help loosen the wood.  That's when the crack sound happened.  It turns out that the out layer of ply cracked about about 10" from the end of the panel.  The crack is about 3-4" long starting from the top edge, going through a stitch hole and heading towards the upward turn in the stern.  Right now the crack is tight, but any flexing of the panel opens it up.  

My first thought is to epoxy another layer of okoume on the inside of the crack to keep it from opening when I close the stern up.  I would think this should be sufficient and if kept small enough it wouldn't affect the flexibility of the panel significantly.  Before moving on this idea I thought it best for the novice to pose it to some of you seasoned veterans out there.  Any thoughts?  

Dave

 

 

 

 

 

 


18 replies:

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RE: WD12 - what was that crack sound?!?!

Good afternoon. You are not alone. We did the same thing with my dad's WD12, Lazlo also had the same issue. The good news is that epoxy is stronger than wood. The important part is the wood needs to be dry before you try to epoxy it back together. Good Luck. JRC.  Here is a link to my post a while back:  http://www.clcboats.com/forum/clcforum/thread/13047.html

Here is Lazlo's page: http://morocz.com/BoatBuilding/DuckBuild.htm

RE: WD12 - what was that crack sound?!?!

Let it dry, flex it open, paint it with plain epoxy, then bend it flat again, and wait at least 24 hours. It will be good to go, with little to no noticeable evidence.    

RE: WD12 - what was that crack sound?!?!

Thanks for the input JRC.  It's strange how comforting it is simply knowing that someone else has had a similar experience!

When you say "flex it open" what do you consider "open"?    I checked out your post and saw the picture of your crack, and it looks significantly more serious than mine.  When my panel isn't flexed the crack is merely a hairline.  My gut is telling me that in order to do your fix I need to make things worse before they can be made better.  

I don't think it really impacts things, but Isuppose I should mention that my panels have been dyed and given a thin coat of epoxy to protect the dye as per Nick Schade's recommendation.  

Dave

 

 

 

 

RE: WD12 - what was that crack sound?!?!

Dave,

As JRC said I had the same problem. It's probably nothing you did, just an udetectable natural flaw in the wood. FWIW, I had my Duck out at Okoumefest yesterday, the 9th one since I launched it, so once repaired they last a long time. In fact, my repair is completely invisible, so you'll be fine.

Go ahead and gently open the crack, it won't make it worse. Don't worry about neatness at this point, a little sanding will fix that. What you really need is the fibers in the crack to be completely saturated because when you close the crack up to its original flatness a lot of epoxy will get squeezed out, so you have to open it enough to flood it with sufficient epoxy such that the wood fibers soak up a good reserve.

If you want to back it up with something use fiberglass, not wood. The outer plywood veneer provides mostly tensile strength and some abrasion resistance. A piece of glass will do a better job of that than a chunk of okoume. My crack has 4 oz glass on each side of it.

Good luck,

Laszlo

   

RE: WD12 - what was that crack sound?!?!

   Thanks for you input as well Laszlo.  Looks like I'm out to the garage to tackle this problem with a solid plan in place!  I imagine that I'll have an interesting grimace on my face as I open this crack up though!  

Dave

 

RE: WD12 - what was that crack sound?!?!

   The pain of opening up the crack lasted only about a minute, but it was rough!  I went from a partial hairline crack all the way to a legitimate top to bottom crack.  It looked bad!  I knew it had to be done though in order to do it right.  

I got the epoxy as deep into the crack edges as I could using a brush, and then put a fiberglass patch on the inside as Laszlo recommended.  I let the epoxy soak in a bit prior to clamping.  It looked good and proper to me before I closed it all up.  I suppose the real test will come tomorrow after work!  Thanks again for the help guys!  

Dave

 

RE: WD12 - what was that crack sound?!?!

I forgot to add that we also doubled the inside with glass. On my dad's WD the piece completely broke off. Hope your repair turns out well.

RE: WD12 - what was that crack sound?!?!

   Unfortunately the update isn't good.  The epoxied joint looked pretty good after removing all the clamping folowing a good 27 hours of curing.  I soaked the wood generously with warm water and used a heat gun to gently warm the wood even a bit more.  As the two sides started to come together where they start to go vertical I noticed a slight kink at the crack right on the top edge of the panel.  I placed a clamp there to releave the stress, and continued stitching, soaking, and heating.  I pretty much had the gap where I figured it should be to accept the tail piece when I noticed the crack was opening up again.  There's just so much stree in that area!  

Was I supposed to glass both sides of the panel at the crack?  How wide should the glass be?  Was the heat gun a bad move?  Any other thoughts or suggestions?  

Dave

 

RE: WD12 - what was that crack sound?!?!

The heat gun was not optimal. Epoxy will soften and lose its strength between 120 and 150 degrees, depending on the brand you're using. You need to keep it cool and continuously apply gentle pressure, possibly for 2 - 3 days, tightening it slowly during that time. I'd also wait at least 72 hours for the joint to cure before attempting to bend it.

Glass would have probably made it too stiff to bend, so you were right not to glass both sides now. Save that until the repair is complete.

The glass should be at least 2 - 3 inches on each side of the crack. If possible, use a bias cut so that both sets of threads resist the tension, not just the warp or the weft.

Laszlo

 

RE: WD12 - what was that crack sound?!?!

Live and learn I suppose huh Laszlo?  

"....continuously apply gentle pressure, possibly for 2 - 3 days, tightening it slowly during that time."  I am assuming this is referring to the stitching of the stern section, and not the clamping process for the crack repair.  

I have to admit that I am a bit unclear how to proceed with reparing the crack for the second time.  Do I simply open the crack again and re-epoxy ignoring the cured epoxy that is there now, or should I attempt to dig some of the cured epoxy out first? The latter sounds like it would do more harm than good.  

Dave

  

RE: WD12 - what was that crack sound?!?!

Dave,

I don't have time for a full answer right now, but at this point it might be worth it to check with CLC customer service, either at http://www.clcboats.com/default/customerservice.html, the link at the top of this page or 410-267-0137 and see what a replacement panel would cost.

Laszlo

 

RE: WD12 - what was that crack sound?!?!

Dave,

I've got a bit more time now. First, some pictures would help a lot. If it's possible to clean it up enough to get it to close up flat, there's still a chance of using this piece of wood. If you don't feel like you can do that, the replacement piece would be the best idea. CLC is very good about support and stands behind the quality of their materials. They will do the right thing, whatever the situation. That's been my experience for 16 years.

So post a picture for more advice from the peanut gallery, but don't be afraid to talk directly to CLC. They want you to succeed,

Good luck,

Laszlo

 

RE: WD12 - what was that crack sound?!?!

Hi Laszlo (and whomever else may be tuning in),

Well I made the big decision today, and your post this morning suggesting a new panel may in order kind of sealed the deal.  I have a habit of getting too detailed in describing my activities in the garage, so I'll spare you the details and cut to the chase.  Since I'm building from plans I have a fair collection of 4mm okoume just sitting around, so I decided to scrap the stern end of the cracked panel and scarf on a new piece. I found a suitable candidate pretty quickly, and cut off the last 15" or so of the panel.  That may have been as painful as opening the crack the other night!  I suppose my only reservation on this whole endeavor is that I'm still learning how to do a proper scarf, but my gut told me that that is what needed to be done to correct this properly.  

I went at it really slowly, and it turns out that I may finally be getting the hang of cutting scarfs!  It was the best one I've ever done by far!  I can't wait to see how it looks once cured.  Should I still wait 72 hours before attempting to form the stern bend?  Any other thought or suggestions?  I guess the botton line question is, "Did I decide correctly with this approach?"  

Dave

 

RE: WD12 - what was that crack sound?!?!

Sounds like you have a good plan. I like to use 1/8 inch cord (550 cord) to bring the ends in. Wrap the ends with about 5-6 feet of cord, mist the wood with a spray bottle, wait 20-30 minutes, pinch the end together a bit, tighten the cords, and wait some more. Good luck, JRC.   

RE: WD12 - what was that crack sound?!?!

Good for you, Dave!  That sounds like the best solution. If I'd picked up on the fact that you were a plans builder, I'd have suggested it myself., but I thought you were trying to save a kit.

Definitely wait as long as you can stand it. The longer the cure the more solid the joint. JRC's plan to close it up sounds like just the thing. You're on your way, now.

Laszlo

 

RE: WD12 - what was that crack sound?!?!

   Thanks again for the input and suppost guys!   I won't be able to get back to the kayak until tomorrow anyway, so that will give me a solid 48 hours of cure time.  As you suggested, I think I'll stitch up the stern in gradual stages over a couple of days using some kind of strapping just to be extra safe.  I don't want to go through this again!  I suppose I could start carving my wife's Greenland paddle as I'm waiting. 

Dave

RE: WD12 - what was that crack sound?!?!

   As expected, scarfing a new end onto the panel worked great!  I was able to stitch up the stern without issue, and the curvature of the stressed panel looked just like the undamaged one.  I did the stitching over two evenings, allowed the panels a generous amount of time to absorb the water, and used two straps to assist in bringing the panels together.  

  Not only did I get over my build obstacle, I also gained a lot of confidence in my scarfing capability.  Practice, practice, and someday I'll actually know what I'm doing!

Dave

RE: WD12 - what was that crack sound?!?!

Good job. In the end only you will know.   

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