Cracks in Deck....Grrrrr

Designs for inboard or outboard power

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Re: Cracks in Deck....Grrrrr

Post by khundley » Fri Apr 01, 2011 7:29 am

You may also be dealing with a difference in shrinkage rates between two species of woods. I built an electric guitar with alternating stripes of maple and mahogany. The guy I get my wood from (and who will supply some for the Key Largo I will start one of these days) used to work for Washburn Guitars. Loved the idea I was trying, but told me right off the bat I would get gaps between the strips. He was soon as the season changed, I had gaps. He said the key is to find wood with similar characteristics, though contrasting colors or Maple and Ebony, or Maple and Wenge, or Mahogany and get the picture.

One way to slow the process has been mentioend above....sealing all sides as quickly as possible....between the glued edges and varnishing the exposed surface, you should be in better shape, but as the boat ages, there's a chance it will happen again.

I wonder, though, if you fiberglassed the decks as well, would the cloth reinforce the wood and prevent this from happening? Is there a reason not to glass the decks short of not creating the additional work?
Ken Hundley

So, my big brother was playing guitar and I figured I'd try it too.
- Stevie Ray Vaughan

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Re: Cracks in Deck....Grrrrr

Post by Onplane » Fri Apr 01, 2011 10:02 am

Okay, so this little discussion has me re-thinking my decking.

Originally, I wanted to do the alternating wood strips. I liked the contrast, and liked the "never have to worry about re-caulking" maintenance program :D

However, I definitely don't want cracks! So here's some questions...

1) I was under the impression that once the wood was sealed on all 6 sides with epoxy, there wouldn't be any "shrinkage" because in theory, once sealed, it shouldn't expand or contract with moisture... Am I just being naive?

2) There is tinted epoxy that can be used for the strips as well right? In this application, will you still get the cracks? Does tinted epoxy give any?

3) How often do you have to "re-caulk" if you go that route?

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Re: Cracks in Deck....Grrrrr

Post by red » Fri Apr 01, 2011 1:22 pm

I could be wrong (it wouldnt be the first ) but I was always taught that no matter what you do wood can and will always move the best you can do is to try and keep the movement to a minimum.

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Re: Cracks in Deck....Grrrrr

Post by sschefer » Fri Apr 01, 2011 8:05 pm

I wonder if you're not only fighting the temperature changes but also the flex of the hull. It almost seems like a no win situation. I think I would use a 15 ply veneer and then route caulk grooves in it and paint them. Once epoxied I think you'd have a tough time telling the faux decking from the real deal.
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Re: Cracks in Deck....Grrrrr

Post by harpoonhedd » Fri Apr 01, 2011 8:28 pm

every species of wood responds to heat and moisture differently...regardless of sealant...yes, sealing w/ multiple coats will be a buffer to the woods potential response...but condensation,cooling and heating etc will ultimately have an effect on movement...being minimal sometimes. having a buffer or boundary of an elastic(or semi) medium like caulk or sealant can make a difference...

teal/holly is a good example...the high silicate levels in teak tend to moderate its movement considerably...holly is fairly consistent in its grain so that it is also a condusive pairing...but on a weathered deck they dont work well together...hence caulk joints.

IMHO leave the alternating decks for interior applications...outside you are just asking for problems...exterior wood decks are already enough work to maintain...

chincoteague island,virginia

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Re: Cracks in Deck....Grrrrr

Post by Onplane » Mon Apr 04, 2011 12:53 pm

Interesting information...

This thread has me just about talked out of going with alternating wood strips in lieu of caulking...

With that in mind...

1) Is caulking the only "flexible" application, or only application that "allows" for top deck flexing? Would tinted epoxy "flex" or is it considered pretty solid too?

2) I'm not familiar with the caulking process at all. I imagine you just space it correctly (with tile spacers or the like) remove excess epoxy between the slats while curing, tape off the deck seams, and then fill in with caulk. Is this about right? How do you get the caulk to lay flat? Do you varnish the deck beams first, then caulk, or varnish over the caulked deck?


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Bill Edmundson
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Re: Cracks in Deck....Grrrrr

Post by Bill Edmundson » Mon Apr 04, 2011 1:37 pm


Look through my pictures you'll see the process. You smooth it with back of a plastic spoon.

Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

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