White Oak and Epoxy??

[Tangusso]

At the risk of great controversy, I have to ask.......what epoxy resin and fillers are best to use on white oak?? More specifically, what products are best for scarfing steam bent white oak ribs? and.....what prep work is critical to ensure the best bond possible? Much of what I have read indicates white oak can be difficult to glue, and I want to be sure I make the best possible choice.

[wizbang 13]

The best possible choice is to substitute Alaska Yellow Cedar for oak, IMO.
You are starting out saying you want to scarph steam bent !!
Are you laminating or just gluing nogs of oak ?
If you are trying to marry 2 pieces of oak, sistering and mechanipickle fastenings are better. And easier to tear out when the oak gets rotten.

[Bob Smalser]

The best epoxy for White Oak and/or for scarfs that will be steambent is called "resorcinol".

http://www.cpadhesives.com/woodworki...-gallon-bottle

[Tangusso]

To be clear, I intend to bend the rib in place with the scarf pre cut. After it has cooled and set I will remove it from the boat and then "glue" the scarf joint and fasten into place. I do not intend the scarf the stock together then bend. I know white oak can be difficult to bond. Is this still the best product for my purpose Bob?

[JimConlin]

There is not general agreement whether it's OK to use general boatbuilding epoxies with white oak.
Some respected builders have adopted West System G/Flex for white oak.

[Bob Smalser]

I know white oak can be difficult to bond. Is this still the best product for my purpose Bob?

There are no doubts about it. And Aerodux is no more difficult to use than any glue that has to be mixed. It is much more flexible in its moisture content and clamping requirements than epoxy, and doesn't require as warm a temperature (as low as 50 degrees F) or tight joints as do conventional resorcinols.

Satisfactory results may be obtained when the moisture content of the
surfaces to be bonded is within the range 6 - 25% but for best results, 12 -
16% is preferred.

[James McMullen]

Why are you borrowing trouble by picking out a wood that is well known to be problematic for glueing? Are you generally lucky? Or is it just in an area of your hull that won't be life-threatening or dangerous when it fails? Why can't you through-fasten or sister frame or something as is standard accepted practice?

Seems to me that that's more likely to be the "best possible choice".

[Cogeniac]

If you get green while oak it should bend Ok without needing to scarf or laminate. Laminating makes the job easier, but with the corresponding comments from the folks on the board about what glue to use or not use.

In a PM you noted that the frames were cracking where they had been sistered (from what I gathered at the ends of the sisters). That implies that the sisters were too short so the stresses on the frames were still high at the ends of the sisters. The sisters on my boat are all sawn and go from the straight part of the frame around the turn of the bilge and about 10 inches up from the last serious curve. Each is probably about 24-36 inches long.

One solution might be to remove the sisters and replace them with longer sisters. Alternatively, you could replace each frame by spiling the shape and making a form for bending, and then install the new frame. Probably a lot easier than bending in place.

[chuckt]

It should be mentioned that resorcinol is not gap fitting. The faces of your pieces need to fit rather well.

GFlex is used by some well-repected yards. (Rockport Marine) Rammilet has used regular West epoxy on his boat extensively. You need the right moisture content whatever you use (15 resorcinol and 12% West ???) and I believe West recommends an alcohol wipe down of white oak before glue-up.

[sailboy3]

Quote from the article on the schooner Valora in WB194:

"To eliminate frame breakage the frames are 'kerfed' before bending, and then glued back together with PL Premium lumber adhesive. PL Premium is polyurethane-based and cures with moisture, which means that the frames can be glued a day or so after steaming"

[kenjamin]

White oak is great for marine use because of the closed cell nature of its structure. Unfortunately for you, this is the same characteristic which keeps it from gluing well especially in "end grain" to "end grain" splices like you need in the splicing of the ribs. White oak won't suck up the glue in the end grain like fir or pine would so your splices on your white oak ribs need to have an especially long bevel on them to work at all. You could do some testing to see what could work satisfactory but I'm guessing that very long bevels on the splices will be necessary for it to work well even with the G-flex – or maybe better still, with the Aerodux Bob recommended.

[Tangusso]

Let me try to explain my plan in detail to see if it clarifies my intent and spurs some suggestions. Take a look at the photo of the exposed ribs. If you look at the second yellow rib from the left and follow it down with your eye toward the keel you will see that it ends (and was forcefully removed) at the bilge stringer. To the right of this rib is a sister that comes up from the keel to the bilge stringer. This was added several years ago and in in excellent condition. Now....to the left of the yellow rib is a short sister that reinforces the area where the original yellow rib and the "new" sister from the keel overlap inadequately. Got all that???

Here's my plan, and please feel free to make suggestions; I intend to remove the short sister that covers the overlapping area of the original rib and short sister coming up from the keel. Since the short sister from the keel is in a very sound pocket, with a solid floor timber atop it, I will leave it alone. I will then remove the vast majority of the original rib, creating a long scarf from the covering board down about 14 - 16", and leaving the original rib high on the topside. I will then scarf a new rib from the topsides down past the bilge stringer and within a foot or so of the keel, resulting in a 12" - 16" overlap with the new sister coming up from the keel. Someone slap me if I'm making no sense....

take a look see.... http://s1211.photobucket.com/albums/cc428/stangusso/

if that link doesn't work, try this... http://i1211.photobucket.com/albums/...ngusso/002.jpg

[wizbang 13]

[James McMullen]

I think laminating a new rib in place using a wood that's suitable for glueing is how I'd tackle it, because it will be easier to get exactly the right curve that you want exactly where you want it. And epoxy is ecellent for gluing the lamination together. Now as for the other part, the scarf is fine, just don't rely on glue alone for your fastening. Use some through-bolts and Bob's yer uncle. Through-bolts and big washers are your best friend here. They are not subject to brittle failure or concerned with wet or old or dis-similar and chemically incompatible wood, nor will they pull-out like a screw or nail can.

[wizbang 13]

Hoo boy! Like to see some more views , the floor timber of which you speak, on top of a sistered piece.
I can't help but think I would lam new frames in ,starting from a long taper just below the beam shelf. The scarphs would be all on straight wood and it would be "easy". Lam by lam, they do not have to be done all at once, worked under the stringer, (hope you have only one), right down next to the floors.

[wizbang 13]

[Tangusso]

Are there not going to be issues bonding white oak to dissimilar woods? Will there not be issues with different woods within the same frame having different physical properties such as hardness, flexibility, rates of expansion and contraction with exposure to varying moisture levels and temperatures? It seems like Richardson (and many other boat builders) chose white oak for very specific reasons.

If end grain gluing of white oak is the primary issue, then should I consider making a long shiplap joint high on the topsides (where I assume the stress is less than at the turn of the bilge), and running the rib down close to the keel and as a sister to the good rib?

[James McMullen]

It seems like Richardson (and many other boat builders) chose white oak for very specific reasons.

Yep. And they didn't use epoxy when your boat was built back in 1935 either.

Dont try to "bond" end-grain white oak to any kind of wood, white oak, or not. Use mechanical fasteners, carefully cut tight joints and bedding compound. We see this age of boat all the time in my shop. There's a well proven and correct way to fix 'em, and it doesn't involve "bonding" white oak to anything. That doesn't last.

[Cogeniac]

This looks like a hot mess. I'd remove one rib at a time up to the point where they are relatively straight (thus under low stress, then I'd splice in a new steam bent rib with about an 8-10 inch ship lap joint as you suggested. That is how the shop fixed my frame heels. The shiplap joint should be easy to make and can be screwed and glued together.

Doing one at a time will assure that the hull shape doesn't change. Pull the fasteners from the planks. Cut he old frame out, splice in the new one, fasten through the same holes in the planks. With only the low stringer you can probably work the bent rib under the stringer and not have to mess with the stringer at all. Seems to me that you could replace most of each rib and forget the sisters altogether. Be sure to fasten the frame to the keel and, more importantly, to the frame timber,

[Gerarddm]

FWIW, Walt Simmons at Duck Trap says to use lacquer thinner to wipe down White Oak before using epoxy.

[chuckt]

Here is a link to a little article West did on the Bolero restoration. It specifcially discusses white oak laminated ribs. http://www.epoxyworks.com/31/pdf/Bolero%20Restored.pdf

[wizbang 13]

Guess it's time for me to check out this G flex.
I do have lots of experience with oak, tearing it out.

[James McMullen]

Don't you have plenty of bad habits to keep current with already, Bruce? I'd leave the white oak and epoxy one alone until you've freed up your schedule.