Sealing Epoxy Red Oak

Discussion in 'Boatbuilding' started by Buzzard11, Nov 5, 2010.

  1. Buzzard11
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    Buzzard11 Junior Member

    I am new to this forum and boat buidling. I have a lot of red oak wood and want to build a 17' Dory. My plan is to use the red oak as framing for rib sides and bottoms. I have been doing a lot of reading regarding red oak and that it is not appropriate for boat building. My questions are is there anyway to seal/epoxy the red oak to eliminate or reduce the problems associated with red oak? I have looked into Smith's Cold CPES and was wondering if that or anything else, West Systems, MAS, Barrier Coat Epoxy, could make this red oak acceptable for building ribs. Since I am new at this I would like as much help as possible. Thanks
     
  2. rasorinc
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    rasorinc Senior Member

    Even white oak is not reccomended in salt water usage as epoxy and the gallic acid in white oak have a bad reaction. I do not know if red oak has the same. I would personally not use it except for interior panaling and cabinets. Maybe you could sell it to a cabinet shop and buy something else. OAK, WHITE From the Glen-L site
    47 lbs. per cubic foot, 3.83 lbs. per board foot
    White oak is a domestic Eastern wood often used in boat building. The problem with white oak, however, is distinguishing it from red oak that is not nearly as suitable for boat building since it is weaker and rots easily unless pressure treated with preservatives. The following characteristics should help in separating white oak from red oak. The heartwood pores will be plugged with abundant hair-like ingrowths known as tyloses, whereas red oak will contain few. The heartwood of white oak is tan or light brown, while that of red oak is reddish or pink. The pores in summer wood are very small and numerous in white oak, but with red oak they are few, large, and open. A chemical test using benzidine-sodium nitrate turns white oak heartwood dark brown or greenish brown, but that of red oak turns light orange. White oak is excellent for steam bending but should ideally be "green" for this purpose and not seasoned. It is durable, stiff, strong, hard, holds fastenings very well, is rot resistant, but is somewhat difficult to work and requires sharp tools. Because of the gallic acid in white oak, it reacts with plastic resin glue when submerged in salt water, and therefore this glue should not be used with white oak under these conditions.
     
  3. Buzzard11
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    Buzzard11 Junior Member

    Thank you for your reply. My problem is that I have cut the red oak to length & width for all of the ribs. I guess I'd have to burn it or pretty much give it away if I don't use it. When I talked with Smith's they thought a couple of coats of CPES would do it. I'm not sure if they were just giving me a sales pitch or if that would take care of it. Any other thoughts rather than buy all new wood? Thanks
     
  4. PAR
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    PAR Yacht Designer/Builder

    The rumors about white oak have been dispelled by me for years and now testing at West System backs this up.

    Red oak is used in boat building, but generally it's used on continuously immersed pieces, like deadwood assemblies. In this environment it's fine. The problem with red oak is it's sucks up moisture like a paper towel. In fact, if you cut a 1/4" square section of red oak, say about 8" long and stick this in a glass of water and blow on the end, you'll actually get bubbles! The fiberous structure of the reds is quite different then the whites and this makes it very difficult to use in the usual and traditional building methods.

    Do yourself a big favor and don't even think about CPES or other penetrating epoxies. These are marketing techniques to take your money. It's diluted epoxy and just about useless for most of the applications the advertisers suggest it's just perfect for.

    Epoxy can seal up red oak for use as framing, but it has to be used in 3/4" thick or thinner stock (thinner is better). Only full encapsulation will do, which means ever side, especially the end grain, every nook, cutout and fastener hole has to have 3 coats (or more) of straight epoxy on it. This will insure a tight vapor barrier with sufficient film thickness, so moisture can't get at the oak. If you need pieces thicker then 3/4", then mill it up and stack the pieces to the required dimension (bonding them together of course).

    Before you coat the red oak with the first coat of epoxy, make sure the surface has been freshly sanded and is wiped with a denatured alcohol damp towel. Xylene and isopropyl alcohol also are good tannin cleaners. This also tends to raise the grain slightly so it gets a good grip. Subsequent coats don't need this treatment, just raw wood.
     
  5. Buzzard11
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    Buzzard11 Junior Member

    PAR - Thank you for your reply. Should I bite the bullet and buy new wood or would you go with encapsolating with epoxy? Is Epoxy barrier coat acceptable to use, 3 or 4 coats? Would Fir be a better choice? I guess I got way ahead of myself. Thanks again.
     
  6. gonzo
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    gonzo Senior Member

    If you seal the wood it should be fine. I don't think red oak absorbs any more water than cypress or cedar.
     
  7. alan white
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    alan white Senior Member

    I suggest buying white or live oak simply because you aren't too far from Boulter supply in (Somerville?), though I'd guess that there are plenty of suppliers around your neighborhood who carry boat woods.
    White oak costs more but it lasts well without any epoxy at all (linseed oil is fine and will turn dark brown over time, which looks traditional and is easily and cheaply re-coated).
    In balance, white oak without epoxy is easier and cheaper as a system than using red oak and having to laminate it in epoxy to prevent checking (water entry crevices).
     
  8. PAR
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    PAR Yacht Designer/Builder

    I wouldn't use oak at all. In a dory you don't need it and the weight will always be a penalty. Use Douglas fir or better yet, what do the plans say? There's a huge difference in weight and other physical attributes between the woods mentioned here. What do the plans say? Lastly barrier coatings are paint for the most part, some actually are epoxy based, but still just paint. Use lamination resin to coat the lumber. Log onto www.westsystem.com and www.systemthree.co and download thier user's and product guides. These will show quite a bit about the products, techniques, mixing, fillers, etc.

    As a general rule you make material substitutions as close to what is spec'ed in the plans as possible. It shouldn't be an arbitrary thing.
     
  9. Buzzard11
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    Buzzard11 Junior Member

    Hi Par,

    The plans call for white oak or spruce. I found the plans online, free, at the following: http://www.sandypointboatworks.com/willapa.html

    I thought it would be a good little dory to get me out on the bays and backwaters of cape cod.

    Thank you for all your input and I appreciate the lessons I learn from this board.
     
  10. mydauphin
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    mydauphin Senior Member

    Yes, it does absorb more water. It is also more dimensional unstable than any other wood. white oak is not as bad. If moisture gets in the wood it will break thru the epoxy. Use another wood. Red oak is he worse...
     
  11. PAR
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    PAR Yacht Designer/Builder

    Wow, spruce or white oak!, Sweet God, someone needs to make up their mind as there's a tremendous difference between the two. White oak is over twice as dense as a plane Jane spruce. If it was me, I'd split the difference and use Douglas fir which is closer to the density of spruce, but does fall in the middle as far as weight and density are concerned. If you're a numbers guy then typical spruces (a lot of species area spruce) will be in the low 20 to 30 pounds per cubic foot range, while white oak is in the low to mid 50's. Douglas fir will be in the low to mid 30's and a good choice (unless you ask Boston, who was abused by a Douglas fir sapling as a lad and now has on going emotional issues with the stuff).

    Buzzard11, I've heard complaints about this particular dory design. The issues are she can porpoise as designed and the most common is once up to a certain speed, she starts chine walking badly, the faster you go the worse it gets. The other most common issue is it turns weird and uncomfortably at speed. Instead of "tucking" and leaning, it skids sideways until the chine digs in, then she suddenly starts the turn. Heavily loaded this isn't an issue.

    Several things have been tried to fix her "issues". The most common ones are chine runners and bottom runners. The chine runners offer more plane surface so she doesn't walk and the bottom runners help her track in the turns.
     
  12. Buzzard11
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    Buzzard11 Junior Member

    PAR - Thanks again. A couple of more questions for you. I'm thinking of using a 20HP. I assume with that power I will face all the issues you described with this design. Do you know of another dory design that is in the 17' range that performs better, requiring low power, somewhere is the 20HP range? Thank you
     
  13. PAR
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    PAR Yacht Designer/Builder

    Dories make for lousy powerboats, is there a reason you want a dory? In fact if you have a dory that's a good powerboat it's not a dory, but a skiff.

    [​IMG]

    This is one of my designs. It's not a dory, not even close, but it is a flat bottom skiff. It's designed for low power and reasonable preformance in shallow water. It doesn't have the wild topside flare of a dory, but it has a whole lot better manners then a dory.

    It can be built plywood over frames, which is the heavy duty version or it can be built as a taped seam boat, which is lighter and has a less cluttered interior. Both versions have the same planking scantlings so getting a hole poked in the bottom isn't very likely (3/4" bottom planks). It also can be built with a couple of glued lap planks along the sheer, which is nice looking for little effort (as shown) or without, just straight up plywood sides, which is easier, but not as much as you'd think. Fuel use is very low with this design, about 1.5 GPH. Lastly, in my mind, it looks a fair bit better then a dory too. She's just an old school, tough, work boat that you can dress up and take to the dance if you want.
    http://i736.photobucket.com/albums/xx1/PARyachts/BYYB-142.jpg
     
  14. rasorinc
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    rasorinc Senior Member

    Par, I cannot open the attachment.
     

  15. Jeff
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    Jeff Moderator

    I think it's the rgb vs. cmyk issue again that a couple other members have experienced -- firefox shows both rgb and cmyk images fine, but Internet Explorer won't display cymk jpegs.
     
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