Alternative Frame Repair

[Bark]

I read about the Alternative Frame Repair (involves grinding out a section of the broken frame, then laminating in strips to fill the void) on pp. 59-60 of Woodenboat's book on Frame, Plank and Stem Repair. I like the sound of the technique, which seems fairly simple, but I wish the guidance was a little more detailed. Here are a few questions I still have (sorry these are pretty basic, but I've never done any frame laminations at all):

1. There is no mention in the article about existing (or new) fasteners - do you just grind right through the old fasteners? Are new fasteners necessary post-lamination? (Mine are copper rivets.)

2. Once the grinding is complete, the strips cut and epoxy spread, the strips are laid (all at once?) into the ground-out void ... how do you keep them there in proper bent position? 2x4s pre-cut as braces, maybe?

3. What kind of grinding wheel do you use (I told you these were basic questions).

Any and all info on this technique appreciated. I just removed my old icebox and exposed some frames - there are about five that are cracked in the same place along a plank seam. Slight hard spot has developed along the seam, but there is no visible problem from the outside. Thanks much.

Ben

[Thorne]

Ben -

How about some more info to help us along -- size and model of boat, material/wood type of both frames and planking, dimensions of same, boat in or outa the watah, etc. Photos are always a big help!

Are you not sistering the frames for reasons of strength, looks, or overall 'yareness'???

;0 )

I don't have the book mentioned, or a lot of experience in frame repair, but would suspect that you'll want to refasten the planks to the new frames in some manner. That would involve either punching/drilling out the old fasteners or putting in new fasteners alongside the old ones.

Let's see what the more experienced folks have to say...

[Bark]

The boat is teak planked on ipol frames. 35-foot Robb Lion, built by Cheoy Lee in 1963. I'm not necessarily opposed to sistering, but that Alternative approach sure looked clean ... Yeah, I would think that refastening would be required, but there was no mention in the article ... maybe they assume you know that ...

Ben

[Dan McCosh]

Re: fastening the laminates. The easy way is to screw them together from the inside, then remove the screw after the epoxy has set. I have done some frame repair using laminates arranged in a kind of stair-step scarf---starting with a short one along the planking, then a longer one, then another, each laminate a few inches longer than the other. This works quite well, is simpler, and ends up with the new section the correct size and shape without attempting to carve the curved strips. Theoretically, the stacked butt joints are weaker, but practically, it works well.

[outofthenorm]

Holding the laminates in place with pre-cut braces will work, but it's a tricky business. Everything works perfectly when you dry fit, but a glue up is damned slippery. I learned that the hard way. Dan's advice of using screws is the better way. Dry fit your laminates and pre-drill at least one fastening so you can use that screw to keep the laminates aligned.

- Norm

[outofthenorm]

Just thought of something else - more of a question for the Forum than answer - How do you avoid gluing the first laminate to the planks? It seems like that would be a Bad Thing. - Norm

[paladin]

waxed paper or mylar next to the planking will prevent the epoxy from sticking...

[Steve R]

I have read of this repair and was contemplating using it on our Richardson, which I believe has White Oak, and was very interested in Searover”s comments. Is there a accepted way to use epoxy with White Oak, or should I plan on replacing all the broken frames with new frames. My concern is that all the breaks are at a critical bend and I was looking to insure that they wont break/crack in the future. Appreciate any comments!
Thank You

[Thorne]

Bark -

If you are concerned about gluing to oak, teak or ipe, you might want to contact Smith & Co. and ask them about their "Oak & Teak epoxy glue" product. http://www.glueoakandteak.com/

I've glued white oak with regular epoxy and not had any failures, but never tried gluing teak or ipe, and usually wiped the wood surface with MEK and let it evaporate (yuck!) prior to glueing.

I would have thought that the 'alternative frame repair' method would be more for rotted frames than cracked ones, where sistering would seem easier and stronger...but I'm no big-boat expert.

[pcford]

There was a guy that promoted this type of frame repair on the 'net some time ago. Haven't heard from him in some time.

It's totally bogus. Let's set aside the issue of glue and white oak; it's well established that there are problems of adhesion.

One of the most important conditions for a frame is straight grain. But with this repair, it is inevitable that the grain runs out!!

[Dan McCosh]

Main problem with this type of solution is that in my experience, a clean fracture in a sound frame is relatively rare. Closer inspection often reveals some rot starting at the hull/frame, etc. Often when cutting out the scarf, the inside is soft. This precludes a repair aimed at fixing a simple crack, at which point I have replaced the whole frame, usually with a lamination. FWIW, I've never had a problem using epoxy to glue white oak, and have laminated several dozen frames.

[Bark]

So, is there general agreement that the Alternative Method mentioned in the Woodenboat book is not the way to go? I found this old thread, which talks about laminating frames (including sisters) in place:

http://www.woodenboatvb.com/vbulletin/upload/showthread.php?t=4430

Is using laminated sisters a better way to go? Thanks.

Ben

[Bob Smalser]

FWIW, I've never had a problem using epoxy to glue white oak, and have laminated several dozen frames.


http://pic20.picturetrail.com/VOL12/1104763/2595357/124272456.jpg

I had success at first, too, but that changes nothing. Keep using WO and epoxy, and a dramatic failure for you is just a matter of time, sometimes months after the glueup.

If you insist, then leave the jointed oak surfaces dry for a couple weeks, as freshly-planed WO appears more prone to glue failures.

The reliable glue for WO is resorcinol, and unlike epoxy, it needs, good fits, curing heat, and heavy clamping pressure, making this method of frame repair on WO problematic.

[Bark]

Bob - Is there an alternative to White Oak for frame repair laminations? My original frames are Ipol. Thanks.

Ben

[Dan McCosh]

http://pic20.picturetrail.com/VOL12/1104763/2595357/124272456.jpg

I had success at first, too, but that changes nothing. Keep using WO and epoxy, and a dramatic failure for you is just a matter of time, sometimes months after the glueup.

If you insist, then leave the jointed oak surfaces dry for a couple weeks, as freshly-planed WO appears more prone to glue failures.

The reliable glue for WO is resorcinol, and unlike epoxy, it needs, good fits, curing heat, and heavy clamping pressure, making this method of frame repair on WO problematic.



My experience now dates to some 35 years or so, from the first laminated rib.
I've looked into technical issues involving the adhesive qualities of epoxies a little, and in general, the stuff in common use for woodworking depends heavily on its ability to penetrate the wood surface for a bond. This leads to the conclusion that any dense hardwood is not going to have a bond--relative to the wood strength--as good as the bond in a softwood.
This greatly simplifies the issue, but at least puts it into perspective. I don't attempt a truly structural bond in hardwood with epoxy, or any other glue, for that matter. As one example, in the case of the laminated ribs, by the time they are fastened in place, there isn't much actual strain on the glue joint. That's likewise true of most scarf joints.
Might add that in an effort to increase the epoxy penetration, I use unfilled epoxy as a primer, then use filled epoxy in the joint.
I've always suspected that glued joints in wood only have full strength in situations where there is a very large surface area relative to the localized strength of the wood--such as cold-molded laminates, very long scarfs in mast sections, etc. Anything less than that is prone to failure under high loads, fatigue, impact, etc. .

[Bob Smalser]

Bob - Is there an alternative to White Oak for frame repair laminations? My original frames are Ipol. Thanks.

Ben

The best alternative it to replace the frame.

I don't know how it takes glue...look for a USDA paper on it....but what I'm reading isn't favorable so far in that regard:

http://www.fpl.fs.fed.us/


Merbau, Ipil....Malaya, PI, New Guinea. Genus Intsia, commonly I. bijuga. Coarse, interlocked grain.....density/strength properties similar to hickory....stains black with moisture or iron.....gums saw teeth and cutting edges.

A number of tropicals don't take glue well, and whether it's used for furniture or takes a finish well isn't a good indicator if your purpose is to laminate frames.

Smith of "Rot Doctor" fame advertises a new epoxy made for WO and tropicals, but whatever he has certainly hasn't stood the test of time, even for those who trust his rather extravagant advertising claims about his other products.

[erster]

I would make a template of the area hull shape, and make a new one or at least a new section off the boat. Just cut the broken parts out, the best you can and clean the area up to a good position. This stems from having several that are weak or cracked. You can make it over sized a bit and then sand or grind to fit. Considering the boat and hull materials, I don't think that using oak is that important, if you intend on using a laminate layup. If you are saying that the boat is fastened with rivets, it may also that you can pull the rivets through to the inside without disturbing the hull side, and back fill the holes. Then you can refasten the boat with new predrilled holes, from the inside out, so you can find the area that you need to counterbore new holes and use wood screws, and then spot in the areas. In my opinion I would fell better about the repair.

[Bob Smalser]

My experience now dates to some 35 years or so, from the first laminated rib.


Any assumption that those of us who think gluing WO is unreliable lack your experience or technique using various glues and wood over time... is mistaken.

[Dan McCosh]

Any assumption that those of us who think gluing WO is unreliable lack your experience or technique using various glues and wood over time... is mistaken.


The 35 years I was refering to dates to the first effort at laminating a white oak rib--which, as it was on my boat, I could follow the results for about 10 years before I sold the boat. More recently, some of the laminations I have been able to follow up on are about 20 years old now, some with the ends soaking constantly in bilge water. I wouldn't generalize about gluing white oak with epoxy from this. I have a good deal of confidence in white oak laminated ribs glued with epoxy, however.

Also--is that photo of a failed glue joint? It looks badly starved for adhesive.

[pcford]

I have a good deal of confidence in white oak laminated ribs glued with epoxy, however.

Also--is that photo of a failed glue joint? It looks badly starved for adhesive.

White oak and epoxy problems are well known. Sometimes it works. Sometimes it doesn't.

Feeling lucky?

[Bark]

Assuming I didn't replace the entire frame as recommended, is there any wood that would be suitable for laminated sister frames, but would not have the delamination concerns of white oak? I think I'm hearing that there really isn't ...

[erster]

Mahogany is pretty darn good with epoxy. I wash all of my hardwoods with Laquer Thinner, or at least acetone and then glueup after most has evaporated. Wet out the wood with a thin layer of slury mixed thickened with cabosil or high density 404 filler from West System. Scratch around some of the yards, in your area and you find enough to do your job with venturing too far from home. .

[Bill Mercer]

Why not cut the broken frames back to flat spots above and below the break, use a hardwood wedge guide to cut the end off at a suitable angle for scarfing, then bend in a replacement section of the same wood (probably next to the frame, so you can bend it before cutting the scarf), cut the scard on the replacement frame, butter the joint up with yer favorite sticky stuff/bedding compount(epoxy, tar, chewing gum, 3m5200), then refasten through the scarf joints with rivets and through the new section with whatever is there before? An 8 or 10 to one scarf, held tightly with rivets, ought to at LEAST be a lot stronger than the broken frame, and you're not putting all your trust in adhesives in damp hardwoods. Hopefully any extra holes in the planks for the rivets will be small, and the solid wood bent frame will do a better job of taking a fair curve than a bunch of skinny laminae, which means nicer looking planking.

Not that I know what I'm talking about, since my bent frame experience comes only from one SOF kayak.

[outofthenorm]

One of the most important conditions for a frame is straight grain. But with this repair, it is inevitable that the grain runs out!!

Sorry, but I'm not sure I understand what you mean here. Can you explain further? Why inevitable? What am I missing?

- Norm

[Bark]

Norm - I could be wrong, but I think he means that if strips are laid into the concave "dish" ground out of the frame, then the ends of these strips will inevitably be positioned on the top of the frame ... thus the "run out". Does that make sense?

Ben

[outofthenorm]

Does that make sense?

Yup. I'm a bit slow sometimes.;)

[outofthenorm]

Question for the experts: Is it absolutely neccesary to glue up the laminates of a sister frame? I know some builders kerf frames before bending them in dry and fastening. Assuming no glue and enough fastenings, you'd then be free to use white oak - or anything else suitable. What's the thinking on this?

Sorry for borrowing your thread, Bark, but this is an area where I need some education - Norm

[Bark]

Interesting stuff. But back to Woodenboat's Frame Stem and Keel Repair for a moment. Page 8 this time. They talk about my problem - adjacent frames broken along the same plank seam - and suggest (if sistering) that the bad part of the frames be removed completely, with the sisters placed alongside and (according to the drawing, anyway) fastened sideways into the original (now reduced) frame. Idea being that this will help draw the plank back to its original position (and cure the chine that has developed). This is the first I've heard of fastening the sister to the original frame. Comments on any of this? (I had thought that anything described in the Woodenboat Series books was borderline gospel, but given the lack of enthusiasm for the "Alternative Method", now I'm doubting ...).

Ben

[Stiletto]

I was under the impression that the definition of 'sister' was that they were often fastened to the original, not merely adjacent.

[erster]

Question for the experts: Is it absolutely neccesary to glue up the laminates of a sister frame? I know some builders kerf frames before bending them in dry and fastening. Assuming no glue and enough fastenings, you'd then be free to use white oak - or anything else suitable. What's the thinking on this?

Sorry for borrowing your thread, Bark, but this is an area where I need some education - Norm

I think all of this depends on the location of the crack as to cutting any curve in a new solid frame. or laminating a new one. Location and how far down the crack goes, especially in a round bilge boat, dictates how you proceed with the repairs, with the materials, whether you can get by with solid sawn or in some extreme cases of curve, the necessity for steam bending in place.

You sounded like laminating was the original way to go. Can you post and pictures that will help us?

[Stiletto]

Yes, I had made an assumption based on some I had seen, I think it was done that way because the cracks were small and hull shape hadnt been lost, so the sister was more of a strengthener of the original. Not something I had thought about much. Thanks for the clarification.

[Bark]

With the possible substitution of another wood for the White Oak mentioned, I'm leaning toward the following (from Dale Genther in an old post):

Dale Genther
posted 09-21-1999 08:24 PM
--------------------------------------------------------------------------------
I sistered about 15 frames on my boat six years ago using laminated white oak which I did "in place". I cut the oak strips on my bandsaw, about 1/4 inch thich. I did not sand them to a smooth finish, but left the bandsaw blade marks on them to provide some tooth for the West System expoy to hold to. Also I reasoned the saw marks ridges would prevent the epoxy glue line from being squeezed to thin for a good bond. As epoxy should have a thicker glue line for proper bonding than other glues. The first lamination I laid onto the inner hull surface set in 3M101, rather than epoxying the frame to the hull. I used small silicon bronze ring nails to hold it to the curvature of the hull. Each following lamination was epoxied to the previous one and held with the ring nails. I found it best to first drill pilot holes, at home, for the nails into each laminate every few inches to make setting the nails quick and easy. After it had set I fastened them from the outside using bronze screws and bunged them. As I was laying inside the cockpit lockers to do this it really helped to have someone out in the cockpit coating the pieces with thickened epoxy and handing them into me. We also wetted out the pieces of laminate with unthickened epoxy bofore coating them with the thickened epoxy. I think this in addition to the sawblade marks I left helped the epoxy bond to the wood and so far there have been no failures. The other thing to consider doing is to wear a complete Tyvek painters suit, cap and gloves. As when working with that much epoxy in the tight quarters I was, I would have been coated with the stuff if I hadn't.

[Dan McCosh]

This is a pretty standard procedure. The main drawback is the working conditions--either temperature or access to the hull. Might note that as I pointed out earlier, this uses metal fastenings to secure the laminates, hence means the bonding itself is not that all that critical. Might note the same technique works to replace a rib that has been removed, rather than sistering it. It's pretty much what I've done on occasion to replace sections as well.

I have generally laminated the frames on a form, with the shape set from a template taken off the hull inside. This works well, but the springback is problematic, and clear access to the hull also is necessary.

I would also want to know what broke the frames to begin with, which would have some bearing on how to repair them.