Ross M
10-26-2002, 02:39 AM
Author Topic: Frame repair
Evan Showell
posted 09-18-1999 01:31 PM
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I've got three cracked ribs on the Dragon that'll need replacement (too far gone to sister/splice, etc.) I'll probably laminate new frames as opposed to steaming them. I seem to recall an article from a recent past issue of WoodenBoat about using taped together card stock to obtain the proper contour of a frame. I've searched the index and can't seem to find it. Anybody remember the issue and article? Thanks. Also, any suggestions for suitable laminating stock and epoxy would be welcome. I also remember hearing somewhere that five was the magic number of laminated plys. Any opinions on that (of course I know no one in this forum has any opinions about anything -- at least not strong ones).
Bob Cleek
posted 09-18-1999 01:52 PM
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Why worry about card stock to take off the shape of a frame so you can build a laminating jig when your boat itself is the ultimate laminating jig? Remove the old frame and laminate in place. You do want more than two or three laminates, but beyond that, the bending ability of the wood is what it's all about. Good dry white oak, about a quarter inch thick, or less, depending on your bending requirements will work find. WEST System epoxy googe, or the equivalent, with colloidal silica thickener to keep it from running all over down into your bilge is the stuff to use. Epoxy the laminates in place right on the inside of the planking, using staples to hold them in place, or sticks wedged against whatever, or make your wife hold them in place until the epoxy dries. One on top of the other until the frame is built. Then fasten as usual from the outside. You can use that puke green Scotch lacquer proof masking tape to make a clean job of it. Saran Wrap will keep it from sticking to various things you don't want it sticking to. Make little U shaped plywood "clips" that are square in section and wedge these over the frame to keep the sides of the laminates fair and even. Works like a charm.
Stan Derelian
posted 09-19-1999 12:40 AM
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A note on the West epoxy that Bob mentions. I've done some oak laminating recently, and have used an epoxy, G2 from Industrial Formulators in British Columbia. It is more forgiving than the West product, can be varied in proportions of resin and hardener to give various levels of flexibility, and is touted to work well with acidic woods and dampness. So far I have found it to be what it claims. I use it with the West 404 filler. --- Also, thanks Bob for the "plywood clip" idea. I'll be using it tomorrow.
K.E. Baisch
posted 09-19-1999 10:27 AM
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I think that the article you have in mind may be Peter Spectre's commentary as he restored his own Thames skiff. Issue # 125.
Bob's way is a good way though. That's what I would do. Except for the part about your wife. Borrow Bob's wife for that.
(That woman must have nerves of steel).
The number five is a good number but it isn't a magic one. There are many variables; how thick each laminate must be, how beefy you need the final frame to be, how long etc.
What you want is an ODD number of laminates. People often think of that as asymetric and imbalanced when in fact the opposite is true. An odd number gives the forces a center to work off of. Like a bridge, it has a beginning, a middle and an end. Or better, like a man on a high wire with a long pole. He maintains equilibrium (ie his balance) because he is at the center of two other forces (the weight of the long pole at either end).
If you use an even number, forces try to find equilibrium between the two middle laminates, putting the whole thing in (even greater) static tension, inviting failure caused by sheer.
Also, odd numbers are aesthetically more pleasing to the eye. Look around you, in your house and on your boat. You'll see this in action. If something seems stiff and you can't quite catch why--count. You'll likely find an even number in the mix.
Not that you'll invite your friends over to oooh and ahhh over the laminary beauty of your frames, but it is a good general rule to have in mind when you build.
Regarding epoxies,
I have used West system for years and am happy with it except that I am developing a slight sensitivity to it now. Tried MAS resins this year. Like that too.
Evan Showell
posted 09-19-1999 02:55 PM
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Thanks for the helpful replies. I think I'm going to take up Bob's suggestion of laminating in place. Unless I'm missing something, in order to get the laminated frames to follow the curve of the hull, I'll need to staple the first laminate in place from inside the hull. Those staples will be buried by the subsequent laminate layers and the epoxy between the first and second laminates never to be seen again. Alternatively, I could staple from outside and remove the staples later. Is there a particular convention which would dictate stapling inside out or outside in? The chief advantage I see in stapling from the outside is that the staples could be removed when they've served their purpose. I am, however, working with a bright mahogany hull and I hate the idea of a bunch of little staple pin holes scattered around the planking.
Dale Harvey
posted 09-19-1999 03:48 PM
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I don't know what kind of staplers you folks have, but I havn't found a manual one that will drive monel stapels thru hardwood reliably. Monel or copper wire are the only things I'd leave in. Laying up one layer at a time I've had good succcess with drywall screws from the inside. With an electric driver removing them isn't bad and you'll get plenty of clamping force for thicker laminations. Pre-drill the lamination your setting to avoid splitting and make screwsetting a one handed operation.
Bob Cleek
posted 09-19-1999 04:40 PM
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When I say staples, we're talking a pneumatic staple gun, something way beyond anything you can achieve with a manual Arrow stapler! You epoxy the first laminate to the inside of the planks, then pull the staples. Only do one or two laminates at a time and pull the staples when the epoxy dries. You can use Gougeon's technique of stapling over plastic strapping tape and then pulling the tape to take the staples out. I've never done this and have my doubts as to how well it works. A staple puller made from a screwdriver would, for the small number of staples involved in framing, probably work better. As an alternative to stapling, I suggested using wood beams wedged against the laminates. This is tricky, but depending on your circumstances, may work better. Cut a bunch of wedges ahead of time... or buy them ready made at the hardware store... (sold for fairing decks and doorframes, etc., since carpenters never get anything straight! LOL) Take a 2x2 and wedge it between whatever it will lay or clamp on inside the boat and then wedge under the end against the laminate.
Short drywall screws (which won't go through the planking!) are a great solution as well. A SMALL dab of grease on the TIP of the screw (not the whole thing) will ensure that they come out a lot easier. The holes can then be filled with thickened googe and the next laminate laid. You want the grease to just coat the inside of the screw's hole, though, since if it gets all over the laminate, the googe won't stick to it at all.
I am greatly impressed by Karen's observations on the number of laminates. It seems she is far more sophisticated than one would imagine for a person so new to the forum! There's hope for her yet, despite her chromosomal handicap! (God, I love a woman who's developed an epoxy sensitivity!) LOL... She's right, for sure. Glue two pieces of wood together and each will fight to twist to where it's comfortable, with the stronger winning out... hence, a warp where you don't want it. But, take three of the same size and the two weaker ones overpower the stronger one and they stay put where you want them... and so on. I do think that beyond five layers, the problem becomes dramatically diminished, such that it makes little difference if you have eight layers rather than seven or nine.
I certainly would not mess with putting any staples or screws THROUGH the planking! Do it from the inside. That's the beauty of the technique. Be sure to clean up the googe that squeezes out between the laminates right away with vinegar or acetone. Otherwise, when it hardens, you will have a major mess. Inside the hull, vinegar is a lot less toxic than the acetone fumes, if you don't mind your boat smelling like pickle jar (or a douche bag, as noted in previous posts.)
[This message has been edited by Bob Cleek (edited 09-19-99).]
Evan Showell
posted 09-19-1999 08:58 PM
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Bob -- Can I get away with not epoxying the first laminate directly to the planking, but relying on staples, drywall screws, etc. to create the right shape? Somehow epoxying the first laminate directly to the planking doesn't sit well with me. Of course, that would involve leaving the first set of monel staples in place.
[This message has been edited by Evan Showell (edited 09-19-99).]
Andrew
posted 09-20-1999 10:32 AM
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As a corrallary (sp?) to Evans last question, if you do epoxy the first laminate to the planking, is it necassary to fasten the planking to the rib afterward?
Bob Cleek
posted 09-20-1999 05:50 PM
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Well, there comes a time in every boatworker's life when the only answer is "how the hell do I know!" LOL... Sure, you can simply staple the first laminate and build up from there, then fasten mechanically when the frame is fully built up, but why would you want to? If you are considering replacing a plank that has been epoxied to the frame, it is going to yank off with a big crowbar anyhow! So, I guess I'd say, if it makes you feel good, just do it! I doubt it really makes any difference. The point of epoxying the first one down is just to hold it in place really well and fill voids between the plank and the frame.
On the other hand, unless you are doing a meticulous epoxy layup, I would never rely on merely the epoxy adhesive to hold a replacement plank in place. While it may well hold fine, there is probably so much crud on the inside faces of the planks that it would not be possible to get a really reliable bond. Besides, you've got the fastening holes all drilled and countersunk in the plank right there all ready, so what's a couple of screws per plank?
Hope this helps!
Ed Harrow
posted 09-20-1999 10:58 PM
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Allen Taube, in his book the Boatwright's Companion, suggests setting up temporary stringers from adjacent frames. You must screw or clamp temporary hangers to the frames to hold the stringers, then use wedges to hold the laminations against the hull (and each other).
I think this book is out of print, I could copy these pages for you. Also there is Trefethen's book. You might want to at least read it, but there is a lot of good stuff in it, you probably should buy it.
John Gearing
posted 09-20-1999 11:53 PM
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Bob et al,
I think Evan wants to know how to laminate his frames in place WITHOUT using staples, screws, or epoxy to fasten the first laminate in place. If it were me, I'd figure out how to fit shores to hold the full stack of laminates in place and in alignment, then I'd start buttering laminates and slapping them in there. Then I'd sink my fasteners from the outside before the epoxy cured. I'd probably use bolts and nuts with big washers under them. Except down at the keel though, where I'd be tempted to remove the garboard so I could put a nice screw into the keel. Maybe you could drive a long screw through the plank and the heel of the frame and into the keel. I'd avoid gluing the laminated frame to the inside of the planking. It will just make a hard spot in the hull until wood starts moving and the wood fails on one side of the glue line.
Bob Cleek
posted 09-21-1999 12:01 AM
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John, that was what I was trying to explain, but the proper term, "shores," escaped me. That's one way to hold the laminates in place. The other is the one describe in Boatwright's Companion. The problem with that one, however, is that you may not have a frame on either side of the one you are laminating which is accessible for attaching the bar/brace across. Wedges are used under the cross piece fastened to the adjacent frames to hold the laminates in place. While it does take longer to wait for the epoxy to set up, I think it is easier in the long run to put one or two, maybe three, laminates in place at a time and build up from there when you are working in the closed confines of a hull. It can get pretty frustrating trying to bend in a whole handfull of epoxy covered hardwood strips!
SEANPEAVEY
posted 09-21-1999 11:27 AM
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Bob-
I know that White Oak is one of the preferred woods to use for frames but I seem to remember that the Gougeon brothers made mention of the fact that epoxy and Oak don't play well together. I believe it had something to do with the coefficient of expansion being greater for Oak than for other woods. Since the epoxy is rigid, the Oak has a tendency to pull away from it. Any comments?
trull
posted 09-21-1999 12:36 PM
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I've posed this question to Gougeon and they advised wiping the laminates with acetone before gluing. I'm hazy here, but I think it had something to do with the "sugars" in the oak. Also, keep moisture content of the oak less than 10%. I've never seen any failures of any I've done.
Another thing that works well is alternate layers of oak and mahoghany. I saw frames done this way (but using resorcinal) left outside for years without failure
Dale Genther
posted 09-21-1999 08:24 PM
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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.
Dayton Eckerson
posted 09-22-1999 06:25 PM
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Since I too am on the brink of a major frame repair job, I've also been researching the various laminating options out there and have heard similar concerns about the use of white oak in epoxy laminations. Although a lot of people, including many on this forum, have apparently had no problems with it, some glue failures have occurred. While this may be due to factors other than the type of wood used, e.g., improper mixture of epoxy, there have been enough of these reports to give me the heebie jeebies. The two solutions I've heard proffered from reliable sources are (1)using alternating laminations of mahogany and white oak, as mentioned above (source: Frank Luke, son of Paul Luke) and (2) use of ash laminations (source: West technical rep.) This latter method was used by a friend of mine who sistered 20 frames on another Nielsen/Luke yawl about 3 years ago. Good luck and keep us posted on progress. P.S. The WoodenBoat book of reprints on keel, frame, and stem repairs is another source of information you might consult before embarking on this project; although most of the reprinted articles on frame repair deal with steam bending, there is at least one good article in there about laminated frames.
Todd Schliemann
posted 09-22-1999 07:05 PM
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About 20 cracked steam bent white oak frames in my '67 34' sloop were replaced with 1/4" white oak and ash laminations with epoxy back in '91 and have held up very well. Copper rivets at the shear clamp and bronze below. A very nice job done by a previous owner that cared. He even stained them to match the originals. Also with a number of cracked frames he used a scarf repair with epoxy laminations as descibed in a WoodenBoat article some years back. Used on cracks round about the water line. A clever and very successful repair that may not necessitate removing alot of the interior. I plan to use it on some other recently cracked frames I have found. Repair is about 18" long, grind out the frame in an elongated "dish" after removing the fastenings. Lay up the lamininations in the "dish", and fair and refasten. When you can get to the frames and they are exposed to view, this option seems alot more attractive than sisters. Saves alot of bilge and floor work if the cracks are relatively accessible.
Bob Cleek
posted 09-22-1999 11:23 PM
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I KNOW Gougeon says oak doesn't take epoxy as well as some other woods, but it seems to take it well enough. I've seen a lot of oak laminated with epoxy and I've never seen it delaminate. I've heard tell it does, but it must be rare. Perhaps there is another explanation for that happening that isn't the oak's fault? As with everybody else, my oak laminated frames have held up splendidly.
Ian McColgin
posted 09-23-1999 01:48 PM
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Oak & teak both got bad reps for epoxying due mostly to the sugars & oils respectivly, and trull's right that acetone cures the problem - just do that wipedown outside the hull with good ventilation and gloves. Alternate layers can look nice - the artistry and spring of an ash&mahogoney tiller is hard to beat - but if you're going to have a problem gluing to a surface, mixing surfaces only increased the predictability of which side of the glue line any failure will occur on.
Oak's lengthwise porosity is a problem. Be sure to flood the endgrain with something thin like CPES. Depending on how you handle the hood-ends, this may mean the 'butterer' holds each laminate upside down and floods what will become the bottom endgrain. You can always get the top later. Or you might laminate in-place with shoring but no mechanical or glue attachment to the hull. When it's completed, take the frame out and flood the end grain. Oak is a gas this way. Depending on the length of your sticks and how cured, you can actually end up with a structure that has epoxy all but bonding cells together. G'luck.
John Gearing
posted 09-23-1999 04:15 PM
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Or use resorcinal glue instead of epoxy.
Bob Cleek
posted 09-23-1999 11:51 PM
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Okay, might as well ask it now... The traditional boatbuilder's preference for white oak (Quercus alba) over red oak (Quercus rosa?) seems to have been the superior rot resistance of the white, owing to grain structure, etc. If we soak red oak in CPES and otherwise cover it with today's more or less water resistant coatings, does red oak become a more viable alternative? Anybody had any experience with this blasphemy?
Evan Showell
posted 09-25-1999 01:30 PM
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Ok -- jumping right back in with both ignorant feet. Why is it that frames always crack right at the turn of the bilge? If I opt for laminating, let's assume that I start with a solid white oak piece of frame stock approximately 1 x 11/4 x frame length (the finished dimension of the frames). I could have that particular piece of stock cut down to 1/4" thick strips for laminating and be effectively reassembling the solid wood into its old grain pattern (approximately) or I could mix and match. Any downside to either approach? Also, if I'm just cutting the stuff into strips anyway any point in paying the substantial premium (c. 40%) for quarter sawn framing stock? Two final questions: 1) the Dragon's frames are closely spaced -- no more than a foot apart each. Any down side to removing the offending frames and probably the garboards and a plank or two and letting the boat sit that way (covered of course) outside in the northern N.J. winter while I laminate up new frames on a jig in the warmth of my basement with the new laminated frames being replaced this coming Spring? 2) Re: screw removal -- I got the brace at the local junk shop for $5. Any advice as to where I can get suitable bits? Thanks as always.
Bob Cleek
posted 09-26-1999 01:06 AM
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I'll answer the ones that come to me... the frame breaks at the sharpest point of its bend because the bending at the outside edge of the radius has to cover more distance, effectively stretching or even breaking the grain structure there. Take a piece of batten wood and bend it till it breaks. It will break at the apex of the bend every time. Frames are no different. Also, putting a fastening or two right there is going to only help matters along. The break takes the path of least resistance, so you'll find the crack where the rivet goes through nine times out of ten.
I don't think there's any need to use quarter sawn stock for laminated frames. Plain sawn will bend a whole lot easier as well. I'd mix the laminations, rather than stacking them up the way they were sawn. There is more strength in unaligned grain than in grain going all the same way.
Screwdriver bits for a brace are hard to come by. I don't know were you'd get them, but it should be pretty easy to take a piece of rod, square the end and grind a driver tip on it. That's what I did to make mine. I couldn't find them for sale anywhere.
Scott D. Rosen
unregistered posted 09-26-1999 09:09 AM
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For the bits, try Jamestown Distributors.
Jim Moser
posted 10-02-1999 11:32 PM
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hello does this work?
Jim Moser
posted 10-03-1999 12:27 AM
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I am new to this E-net stuff.I couldn't help but respond to the epoxy-white oak subject.I've seen too many epoxy glue joints fail when not totally encapsulated and protected from the environment,so I decided to run some tests before installing 28 2x2 inch frames in a comm. fish boat's fish hold. Using three epoxys -systems three-west systems-smiths tropical hardwwods epoxy.I glued them on a form and clamped and let cure for a week. All three lams split down the glue line when attacked with chissel and mallet.So I tryed the old standby (Weldwood plastic resin glue),this lam was indestructable when attacked the same way- destoyed the wood before the glue line.Weldwood is cheap,reliable,water mixed,temperature tolerant,and friendly to the senses,so why use that stinking epoxy? We used 7/8 bronze ring nails and dolphinited the first board down. Had to pre-bore and set each nail.I think the proper air stapler would work good.I've also glued them up in bundles and driven them down through the removed coverboard in double planked hulls and up from the bottom-works good.
Scott D. Rosen
unregistered posted 10-03-1999 08:23 AM
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How well does the Weldwood last over time and continual exposure to water and sun? Where can I learn more about it?
Jim Moser
posted 10-03-1999 12:07 PM
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Scott- that original Weldwood test frame is still sitting on top of my fence after 5 years of rain and Ca. sun it is still indestructable.It is technically not a waterproof glue because it does not pass the boiling water test,I can quote a respected old boatbuilder (just don't boil your boat).From experience and observation it is the most reliable and conditions tolerant glue on the market.It is avaliable on the shelf of any good hardware store.
trull
posted 10-03-1999 04:30 PM
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Weldwood certainly works and that was all I used before Epoxy was available. In my experience close fits and good clamping produced the best results. It does contain formaldehyde so wear a mask when mixing. Not that epoxy isn't another poison!
George
posted 10-05-1999 02:09 PM
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Screw bits for a brace are easily made by cutting the handles off of old screwdrivers (often available at yard sales and/or flea markets) and grinding a set of flats in the end where the handle once was.
JIM MALONEY
posted 10-05-1999 04:32 PM
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BITS FOR BRACES ARE AVAILABLE THROUGH TRU-VALUE STORES AS A SPECIAL ORDER. IT IS CALLED "4 PIECE IMPACT BIT SET" MANUFACTURED FOR COTTER AND COMPANY. PART NUMBER 99575 08002. ALTHOUGH THE SET IS FOR IMPACT WRENCHES, THEY WORK PERFECTLY IN A BRACE AND ARE VERY HARD STEEL - THEY WILL NOT BEND OR TWIST. THERE ARE A #2 AND A #3 PHILLIPS AND A 5/16" AND A 3/8" STRAIGHT BIT IN THE SET. IF YOU CANNOT FIND THEM LOCALLY, LET ME KNOW.
Evan Showell
posted 10-23-1999 02:21 PM
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Thanks for all of the helpful replies. I've been reading up. Most recently Trefethen's book. Anybody see a problem with simply cutting out the cracked portion of the frames and laminating a repair section in place? It would be significantly less work. I am, however, ultimately interested in doing the correct, lasting repair. I don't want an "easy" repair which will not be effective. Also, if I laminate the frames on a building jig instead of using the boat as a jig,I've given some thought to taking the measurements form the outside of what is a very fair hull and then simply adding the known planking thickness to arrive at the final frame shape. Is this heresy? Will I be sent straight to Davy Jones locker for attempting this? The frames are 1 1/4" wide by 1" deep spaced about every six or eight inches. The cracked ones are toward the stern and the cracks are, predictably right at the turn of the bilge. They are oriented along the grain of the oak from keel to sheer, rather than across the grain, i.e., fore and aft, and none is longer than about six inches. Insights appreciated as always.
Dale Harvey
posted 10-23-1999 11:41 PM
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Evan, in the time you've spent studying and fretting over this simple repair a competent professional could have sistered the ribs, wooded the hull, CPESed it, and if the weather held would have the final coat of paint on. If you have to have a museum quality invisible repair, pull the deck and replace as built. If you want to use the boat, laminate some sisters in place spanning four or five planks beside the old rib and stagger the fastenings for the sisters in the planks so you don't split them. Trying to cut the old ribs for a decent staggered scarf while standing on your head in the bilge will be a real pain for less strength.
Bob Cleek
posted 10-24-1999 01:35 AM
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Dale is right... just go for it! I wouldn't worry about trying to build a jig, not only is it an unecessary step which may result in error, while laminating in place is certain to be accurate, but you may well end up with a nice frame that you can't fit into the boat because of other stuff in the way. You will be better off sistering next to the old frame than trying to scarf in a repair. It is a devil of a job and not necessary. Most all older wooden boats with steamed frames have sisters and it isn't a black mark against them. They are stronger for it.
Evan Showell
posted 10-24-1999 08:49 AM
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Dale -- I appreciate the kick in the butt. I 'll admit to a tendency to overthink things, however, I will not have the weather, time or assistance to make the necessary repairs until the Spring. Thought with a jig I might laminate new frames in the basement over the Winter and be ready to go when the weather improves. I did consider sistering, but am edgy about the thought of introducing local hard spots in the hull which is reputed to be a result of sistering -- although I've never actually experienced the problem. I am familiar with sistering as the Tumlaren I have an interet in has several sistered frames. I'd prefer to avoid sisters on Puff if I can since the hull is mahogany finished bright and I'd prefer not to have the extra bungs visible from outside. I notice that some of the frames already have a graving/dutchmen repair which appears to have been riveted in place. I'm not looking for "museum quality" -- I just thought I'd survey the available knowledge before diving in with a particular repair method. As always, all advice is appreciated if not necessarily followed.
noquiklos
posted 10-24-1999 11:43 PM
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In my admittedly limited experiences, hard spots are more a result of sistering too late than anything else. My 65 year old Blanchard was raced hard through her "middle" age, and has been sistered from the partners, to mid-cockpit on every frame, as well as several twice. She is still tight, strong and sound, doesn't leak a drop, and embarrasses quite a few clorox bottles on occasion. Laminating sisters is easy fast and strong. Go for it.
John Engels
posted 10-25-1999 09:00 AM
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If you don't want the frame epoxied to the hull when you laminate in place, use a piece of poly / plastic (about 4 mil.) between the hull and the first laminate. When the frame is completely laminated, remove the plastic and attach the frame with your fasterer of choice.
MikeGardner
posted 10-25-1999 11:19 AM
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I know many have built laminated frames to replace cracked originals.The new laminated frame will be much stronger than the original bent one. Has anyone with these new lam frames noticed fastenings pulling out or cracks in adjacent frames following the repair? Does the increased stiffness of the new frame adversely affect the rest of them?
Just a thought I had...
Andrew Craig-Bennett
posted 10-25-1999 11:32 PM
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Ah, yes, laminated frame repairs! Can I chip in my two pennyworth here?
"Mirelle" was built in the classic English way, with grown frames every two feet and a pair of Canadian rock elm bent frames between each (Herreshoff would NOT have approved, and he would have been right!) with wrought iron floors on every frame. To add to the fun, the iron floors were bolted to the frames before the planks went on (now find the bolts....)
This was the standard method of building one off yachts in England, because, of course, it saved the cost, in materials and labour, of making moulds, onto which you put your ribbands, in order to bend your frames, before planking, only to throw away the moulds and ribbands later. You could take your grown frames straight off the mould loft floor, cut the bevels on the bandsaw, erect them, ribband up, steam the bent frames and plank up.
(Herreshoff, of course, faced with the cost of making complete jigs for his upside down building method, series built his boats in classes to recover the mould cost!)
The snag is that the CRE bent frames rot, given half a chance (why did we use that stuff, rather than our own perfectly good oak?) and, more seriously because the bent frames "give" more than the grown frames do, the grown frames are liable to crack every time the boat hits something hard.
The two rotten bent frames that she had when I bought her I have replaced with new oak frames, steamed in. There is enough space to get them in behind the beam shelf and stringer since, obviously, these lie on the grown frames.
After our 1987 hurricane, in which the boat was an insurance write off, the grown frames are progressively turning into laminated frames, along the length of the boat! The planks were originally attached to these with turned copper nails; a surveyor could tell the renewed frames, as these have clenches!
Yes, I have seen oak laminated with epoxy fail - not on my boat, but a set of deck beams on a nice Lyle Hess cutter built by a very good builder. However, since the laminations are through fastenened, as they would be on the Dragon, it does not bother me that much. In theory, I would now use resorcinol, and screw each layer one by one.
Evan Showell
posted 09-18-1999 01:31 PM
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I've got three cracked ribs on the Dragon that'll need replacement (too far gone to sister/splice, etc.) I'll probably laminate new frames as opposed to steaming them. I seem to recall an article from a recent past issue of WoodenBoat about using taped together card stock to obtain the proper contour of a frame. I've searched the index and can't seem to find it. Anybody remember the issue and article? Thanks. Also, any suggestions for suitable laminating stock and epoxy would be welcome. I also remember hearing somewhere that five was the magic number of laminated plys. Any opinions on that (of course I know no one in this forum has any opinions about anything -- at least not strong ones).
Bob Cleek
posted 09-18-1999 01:52 PM
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Why worry about card stock to take off the shape of a frame so you can build a laminating jig when your boat itself is the ultimate laminating jig? Remove the old frame and laminate in place. You do want more than two or three laminates, but beyond that, the bending ability of the wood is what it's all about. Good dry white oak, about a quarter inch thick, or less, depending on your bending requirements will work find. WEST System epoxy googe, or the equivalent, with colloidal silica thickener to keep it from running all over down into your bilge is the stuff to use. Epoxy the laminates in place right on the inside of the planking, using staples to hold them in place, or sticks wedged against whatever, or make your wife hold them in place until the epoxy dries. One on top of the other until the frame is built. Then fasten as usual from the outside. You can use that puke green Scotch lacquer proof masking tape to make a clean job of it. Saran Wrap will keep it from sticking to various things you don't want it sticking to. Make little U shaped plywood "clips" that are square in section and wedge these over the frame to keep the sides of the laminates fair and even. Works like a charm.
Stan Derelian
posted 09-19-1999 12:40 AM
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A note on the West epoxy that Bob mentions. I've done some oak laminating recently, and have used an epoxy, G2 from Industrial Formulators in British Columbia. It is more forgiving than the West product, can be varied in proportions of resin and hardener to give various levels of flexibility, and is touted to work well with acidic woods and dampness. So far I have found it to be what it claims. I use it with the West 404 filler. --- Also, thanks Bob for the "plywood clip" idea. I'll be using it tomorrow.
K.E. Baisch
posted 09-19-1999 10:27 AM
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I think that the article you have in mind may be Peter Spectre's commentary as he restored his own Thames skiff. Issue # 125.
Bob's way is a good way though. That's what I would do. Except for the part about your wife. Borrow Bob's wife for that.
(That woman must have nerves of steel).
The number five is a good number but it isn't a magic one. There are many variables; how thick each laminate must be, how beefy you need the final frame to be, how long etc.
What you want is an ODD number of laminates. People often think of that as asymetric and imbalanced when in fact the opposite is true. An odd number gives the forces a center to work off of. Like a bridge, it has a beginning, a middle and an end. Or better, like a man on a high wire with a long pole. He maintains equilibrium (ie his balance) because he is at the center of two other forces (the weight of the long pole at either end).
If you use an even number, forces try to find equilibrium between the two middle laminates, putting the whole thing in (even greater) static tension, inviting failure caused by sheer.
Also, odd numbers are aesthetically more pleasing to the eye. Look around you, in your house and on your boat. You'll see this in action. If something seems stiff and you can't quite catch why--count. You'll likely find an even number in the mix.
Not that you'll invite your friends over to oooh and ahhh over the laminary beauty of your frames, but it is a good general rule to have in mind when you build.
Regarding epoxies,
I have used West system for years and am happy with it except that I am developing a slight sensitivity to it now. Tried MAS resins this year. Like that too.
Evan Showell
posted 09-19-1999 02:55 PM
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Thanks for the helpful replies. I think I'm going to take up Bob's suggestion of laminating in place. Unless I'm missing something, in order to get the laminated frames to follow the curve of the hull, I'll need to staple the first laminate in place from inside the hull. Those staples will be buried by the subsequent laminate layers and the epoxy between the first and second laminates never to be seen again. Alternatively, I could staple from outside and remove the staples later. Is there a particular convention which would dictate stapling inside out or outside in? The chief advantage I see in stapling from the outside is that the staples could be removed when they've served their purpose. I am, however, working with a bright mahogany hull and I hate the idea of a bunch of little staple pin holes scattered around the planking.
Dale Harvey
posted 09-19-1999 03:48 PM
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I don't know what kind of staplers you folks have, but I havn't found a manual one that will drive monel stapels thru hardwood reliably. Monel or copper wire are the only things I'd leave in. Laying up one layer at a time I've had good succcess with drywall screws from the inside. With an electric driver removing them isn't bad and you'll get plenty of clamping force for thicker laminations. Pre-drill the lamination your setting to avoid splitting and make screwsetting a one handed operation.
Bob Cleek
posted 09-19-1999 04:40 PM
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When I say staples, we're talking a pneumatic staple gun, something way beyond anything you can achieve with a manual Arrow stapler! You epoxy the first laminate to the inside of the planks, then pull the staples. Only do one or two laminates at a time and pull the staples when the epoxy dries. You can use Gougeon's technique of stapling over plastic strapping tape and then pulling the tape to take the staples out. I've never done this and have my doubts as to how well it works. A staple puller made from a screwdriver would, for the small number of staples involved in framing, probably work better. As an alternative to stapling, I suggested using wood beams wedged against the laminates. This is tricky, but depending on your circumstances, may work better. Cut a bunch of wedges ahead of time... or buy them ready made at the hardware store... (sold for fairing decks and doorframes, etc., since carpenters never get anything straight! LOL) Take a 2x2 and wedge it between whatever it will lay or clamp on inside the boat and then wedge under the end against the laminate.
Short drywall screws (which won't go through the planking!) are a great solution as well. A SMALL dab of grease on the TIP of the screw (not the whole thing) will ensure that they come out a lot easier. The holes can then be filled with thickened googe and the next laminate laid. You want the grease to just coat the inside of the screw's hole, though, since if it gets all over the laminate, the googe won't stick to it at all.
I am greatly impressed by Karen's observations on the number of laminates. It seems she is far more sophisticated than one would imagine for a person so new to the forum! There's hope for her yet, despite her chromosomal handicap! (God, I love a woman who's developed an epoxy sensitivity!) LOL... She's right, for sure. Glue two pieces of wood together and each will fight to twist to where it's comfortable, with the stronger winning out... hence, a warp where you don't want it. But, take three of the same size and the two weaker ones overpower the stronger one and they stay put where you want them... and so on. I do think that beyond five layers, the problem becomes dramatically diminished, such that it makes little difference if you have eight layers rather than seven or nine.
I certainly would not mess with putting any staples or screws THROUGH the planking! Do it from the inside. That's the beauty of the technique. Be sure to clean up the googe that squeezes out between the laminates right away with vinegar or acetone. Otherwise, when it hardens, you will have a major mess. Inside the hull, vinegar is a lot less toxic than the acetone fumes, if you don't mind your boat smelling like pickle jar (or a douche bag, as noted in previous posts.)
[This message has been edited by Bob Cleek (edited 09-19-99).]
Evan Showell
posted 09-19-1999 08:58 PM
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Bob -- Can I get away with not epoxying the first laminate directly to the planking, but relying on staples, drywall screws, etc. to create the right shape? Somehow epoxying the first laminate directly to the planking doesn't sit well with me. Of course, that would involve leaving the first set of monel staples in place.
[This message has been edited by Evan Showell (edited 09-19-99).]
Andrew
posted 09-20-1999 10:32 AM
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As a corrallary (sp?) to Evans last question, if you do epoxy the first laminate to the planking, is it necassary to fasten the planking to the rib afterward?
Bob Cleek
posted 09-20-1999 05:50 PM
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Well, there comes a time in every boatworker's life when the only answer is "how the hell do I know!" LOL... Sure, you can simply staple the first laminate and build up from there, then fasten mechanically when the frame is fully built up, but why would you want to? If you are considering replacing a plank that has been epoxied to the frame, it is going to yank off with a big crowbar anyhow! So, I guess I'd say, if it makes you feel good, just do it! I doubt it really makes any difference. The point of epoxying the first one down is just to hold it in place really well and fill voids between the plank and the frame.
On the other hand, unless you are doing a meticulous epoxy layup, I would never rely on merely the epoxy adhesive to hold a replacement plank in place. While it may well hold fine, there is probably so much crud on the inside faces of the planks that it would not be possible to get a really reliable bond. Besides, you've got the fastening holes all drilled and countersunk in the plank right there all ready, so what's a couple of screws per plank?
Hope this helps!
Ed Harrow
posted 09-20-1999 10:58 PM
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Allen Taube, in his book the Boatwright's Companion, suggests setting up temporary stringers from adjacent frames. You must screw or clamp temporary hangers to the frames to hold the stringers, then use wedges to hold the laminations against the hull (and each other).
I think this book is out of print, I could copy these pages for you. Also there is Trefethen's book. You might want to at least read it, but there is a lot of good stuff in it, you probably should buy it.
John Gearing
posted 09-20-1999 11:53 PM
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Bob et al,
I think Evan wants to know how to laminate his frames in place WITHOUT using staples, screws, or epoxy to fasten the first laminate in place. If it were me, I'd figure out how to fit shores to hold the full stack of laminates in place and in alignment, then I'd start buttering laminates and slapping them in there. Then I'd sink my fasteners from the outside before the epoxy cured. I'd probably use bolts and nuts with big washers under them. Except down at the keel though, where I'd be tempted to remove the garboard so I could put a nice screw into the keel. Maybe you could drive a long screw through the plank and the heel of the frame and into the keel. I'd avoid gluing the laminated frame to the inside of the planking. It will just make a hard spot in the hull until wood starts moving and the wood fails on one side of the glue line.
Bob Cleek
posted 09-21-1999 12:01 AM
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John, that was what I was trying to explain, but the proper term, "shores," escaped me. That's one way to hold the laminates in place. The other is the one describe in Boatwright's Companion. The problem with that one, however, is that you may not have a frame on either side of the one you are laminating which is accessible for attaching the bar/brace across. Wedges are used under the cross piece fastened to the adjacent frames to hold the laminates in place. While it does take longer to wait for the epoxy to set up, I think it is easier in the long run to put one or two, maybe three, laminates in place at a time and build up from there when you are working in the closed confines of a hull. It can get pretty frustrating trying to bend in a whole handfull of epoxy covered hardwood strips!
SEANPEAVEY
posted 09-21-1999 11:27 AM
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Bob-
I know that White Oak is one of the preferred woods to use for frames but I seem to remember that the Gougeon brothers made mention of the fact that epoxy and Oak don't play well together. I believe it had something to do with the coefficient of expansion being greater for Oak than for other woods. Since the epoxy is rigid, the Oak has a tendency to pull away from it. Any comments?
trull
posted 09-21-1999 12:36 PM
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I've posed this question to Gougeon and they advised wiping the laminates with acetone before gluing. I'm hazy here, but I think it had something to do with the "sugars" in the oak. Also, keep moisture content of the oak less than 10%. I've never seen any failures of any I've done.
Another thing that works well is alternate layers of oak and mahoghany. I saw frames done this way (but using resorcinal) left outside for years without failure
Dale Genther
posted 09-21-1999 08:24 PM
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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.
Dayton Eckerson
posted 09-22-1999 06:25 PM
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Since I too am on the brink of a major frame repair job, I've also been researching the various laminating options out there and have heard similar concerns about the use of white oak in epoxy laminations. Although a lot of people, including many on this forum, have apparently had no problems with it, some glue failures have occurred. While this may be due to factors other than the type of wood used, e.g., improper mixture of epoxy, there have been enough of these reports to give me the heebie jeebies. The two solutions I've heard proffered from reliable sources are (1)using alternating laminations of mahogany and white oak, as mentioned above (source: Frank Luke, son of Paul Luke) and (2) use of ash laminations (source: West technical rep.) This latter method was used by a friend of mine who sistered 20 frames on another Nielsen/Luke yawl about 3 years ago. Good luck and keep us posted on progress. P.S. The WoodenBoat book of reprints on keel, frame, and stem repairs is another source of information you might consult before embarking on this project; although most of the reprinted articles on frame repair deal with steam bending, there is at least one good article in there about laminated frames.
Todd Schliemann
posted 09-22-1999 07:05 PM
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About 20 cracked steam bent white oak frames in my '67 34' sloop were replaced with 1/4" white oak and ash laminations with epoxy back in '91 and have held up very well. Copper rivets at the shear clamp and bronze below. A very nice job done by a previous owner that cared. He even stained them to match the originals. Also with a number of cracked frames he used a scarf repair with epoxy laminations as descibed in a WoodenBoat article some years back. Used on cracks round about the water line. A clever and very successful repair that may not necessitate removing alot of the interior. I plan to use it on some other recently cracked frames I have found. Repair is about 18" long, grind out the frame in an elongated "dish" after removing the fastenings. Lay up the lamininations in the "dish", and fair and refasten. When you can get to the frames and they are exposed to view, this option seems alot more attractive than sisters. Saves alot of bilge and floor work if the cracks are relatively accessible.
Bob Cleek
posted 09-22-1999 11:23 PM
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I KNOW Gougeon says oak doesn't take epoxy as well as some other woods, but it seems to take it well enough. I've seen a lot of oak laminated with epoxy and I've never seen it delaminate. I've heard tell it does, but it must be rare. Perhaps there is another explanation for that happening that isn't the oak's fault? As with everybody else, my oak laminated frames have held up splendidly.
Ian McColgin
posted 09-23-1999 01:48 PM
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Oak & teak both got bad reps for epoxying due mostly to the sugars & oils respectivly, and trull's right that acetone cures the problem - just do that wipedown outside the hull with good ventilation and gloves. Alternate layers can look nice - the artistry and spring of an ash&mahogoney tiller is hard to beat - but if you're going to have a problem gluing to a surface, mixing surfaces only increased the predictability of which side of the glue line any failure will occur on.
Oak's lengthwise porosity is a problem. Be sure to flood the endgrain with something thin like CPES. Depending on how you handle the hood-ends, this may mean the 'butterer' holds each laminate upside down and floods what will become the bottom endgrain. You can always get the top later. Or you might laminate in-place with shoring but no mechanical or glue attachment to the hull. When it's completed, take the frame out and flood the end grain. Oak is a gas this way. Depending on the length of your sticks and how cured, you can actually end up with a structure that has epoxy all but bonding cells together. G'luck.
John Gearing
posted 09-23-1999 04:15 PM
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Or use resorcinal glue instead of epoxy.
Bob Cleek
posted 09-23-1999 11:51 PM
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Okay, might as well ask it now... The traditional boatbuilder's preference for white oak (Quercus alba) over red oak (Quercus rosa?) seems to have been the superior rot resistance of the white, owing to grain structure, etc. If we soak red oak in CPES and otherwise cover it with today's more or less water resistant coatings, does red oak become a more viable alternative? Anybody had any experience with this blasphemy?
Evan Showell
posted 09-25-1999 01:30 PM
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Ok -- jumping right back in with both ignorant feet. Why is it that frames always crack right at the turn of the bilge? If I opt for laminating, let's assume that I start with a solid white oak piece of frame stock approximately 1 x 11/4 x frame length (the finished dimension of the frames). I could have that particular piece of stock cut down to 1/4" thick strips for laminating and be effectively reassembling the solid wood into its old grain pattern (approximately) or I could mix and match. Any downside to either approach? Also, if I'm just cutting the stuff into strips anyway any point in paying the substantial premium (c. 40%) for quarter sawn framing stock? Two final questions: 1) the Dragon's frames are closely spaced -- no more than a foot apart each. Any down side to removing the offending frames and probably the garboards and a plank or two and letting the boat sit that way (covered of course) outside in the northern N.J. winter while I laminate up new frames on a jig in the warmth of my basement with the new laminated frames being replaced this coming Spring? 2) Re: screw removal -- I got the brace at the local junk shop for $5. Any advice as to where I can get suitable bits? Thanks as always.
Bob Cleek
posted 09-26-1999 01:06 AM
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I'll answer the ones that come to me... the frame breaks at the sharpest point of its bend because the bending at the outside edge of the radius has to cover more distance, effectively stretching or even breaking the grain structure there. Take a piece of batten wood and bend it till it breaks. It will break at the apex of the bend every time. Frames are no different. Also, putting a fastening or two right there is going to only help matters along. The break takes the path of least resistance, so you'll find the crack where the rivet goes through nine times out of ten.
I don't think there's any need to use quarter sawn stock for laminated frames. Plain sawn will bend a whole lot easier as well. I'd mix the laminations, rather than stacking them up the way they were sawn. There is more strength in unaligned grain than in grain going all the same way.
Screwdriver bits for a brace are hard to come by. I don't know were you'd get them, but it should be pretty easy to take a piece of rod, square the end and grind a driver tip on it. That's what I did to make mine. I couldn't find them for sale anywhere.
Scott D. Rosen
unregistered posted 09-26-1999 09:09 AM
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For the bits, try Jamestown Distributors.
Jim Moser
posted 10-02-1999 11:32 PM
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hello does this work?
Jim Moser
posted 10-03-1999 12:27 AM
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I am new to this E-net stuff.I couldn't help but respond to the epoxy-white oak subject.I've seen too many epoxy glue joints fail when not totally encapsulated and protected from the environment,so I decided to run some tests before installing 28 2x2 inch frames in a comm. fish boat's fish hold. Using three epoxys -systems three-west systems-smiths tropical hardwwods epoxy.I glued them on a form and clamped and let cure for a week. All three lams split down the glue line when attacked with chissel and mallet.So I tryed the old standby (Weldwood plastic resin glue),this lam was indestructable when attacked the same way- destoyed the wood before the glue line.Weldwood is cheap,reliable,water mixed,temperature tolerant,and friendly to the senses,so why use that stinking epoxy? We used 7/8 bronze ring nails and dolphinited the first board down. Had to pre-bore and set each nail.I think the proper air stapler would work good.I've also glued them up in bundles and driven them down through the removed coverboard in double planked hulls and up from the bottom-works good.
Scott D. Rosen
unregistered posted 10-03-1999 08:23 AM
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How well does the Weldwood last over time and continual exposure to water and sun? Where can I learn more about it?
Jim Moser
posted 10-03-1999 12:07 PM
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Scott- that original Weldwood test frame is still sitting on top of my fence after 5 years of rain and Ca. sun it is still indestructable.It is technically not a waterproof glue because it does not pass the boiling water test,I can quote a respected old boatbuilder (just don't boil your boat).From experience and observation it is the most reliable and conditions tolerant glue on the market.It is avaliable on the shelf of any good hardware store.
trull
posted 10-03-1999 04:30 PM
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Weldwood certainly works and that was all I used before Epoxy was available. In my experience close fits and good clamping produced the best results. It does contain formaldehyde so wear a mask when mixing. Not that epoxy isn't another poison!
George
posted 10-05-1999 02:09 PM
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Screw bits for a brace are easily made by cutting the handles off of old screwdrivers (often available at yard sales and/or flea markets) and grinding a set of flats in the end where the handle once was.
JIM MALONEY
posted 10-05-1999 04:32 PM
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BITS FOR BRACES ARE AVAILABLE THROUGH TRU-VALUE STORES AS A SPECIAL ORDER. IT IS CALLED "4 PIECE IMPACT BIT SET" MANUFACTURED FOR COTTER AND COMPANY. PART NUMBER 99575 08002. ALTHOUGH THE SET IS FOR IMPACT WRENCHES, THEY WORK PERFECTLY IN A BRACE AND ARE VERY HARD STEEL - THEY WILL NOT BEND OR TWIST. THERE ARE A #2 AND A #3 PHILLIPS AND A 5/16" AND A 3/8" STRAIGHT BIT IN THE SET. IF YOU CANNOT FIND THEM LOCALLY, LET ME KNOW.
Evan Showell
posted 10-23-1999 02:21 PM
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Thanks for all of the helpful replies. I've been reading up. Most recently Trefethen's book. Anybody see a problem with simply cutting out the cracked portion of the frames and laminating a repair section in place? It would be significantly less work. I am, however, ultimately interested in doing the correct, lasting repair. I don't want an "easy" repair which will not be effective. Also, if I laminate the frames on a building jig instead of using the boat as a jig,I've given some thought to taking the measurements form the outside of what is a very fair hull and then simply adding the known planking thickness to arrive at the final frame shape. Is this heresy? Will I be sent straight to Davy Jones locker for attempting this? The frames are 1 1/4" wide by 1" deep spaced about every six or eight inches. The cracked ones are toward the stern and the cracks are, predictably right at the turn of the bilge. They are oriented along the grain of the oak from keel to sheer, rather than across the grain, i.e., fore and aft, and none is longer than about six inches. Insights appreciated as always.
Dale Harvey
posted 10-23-1999 11:41 PM
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Evan, in the time you've spent studying and fretting over this simple repair a competent professional could have sistered the ribs, wooded the hull, CPESed it, and if the weather held would have the final coat of paint on. If you have to have a museum quality invisible repair, pull the deck and replace as built. If you want to use the boat, laminate some sisters in place spanning four or five planks beside the old rib and stagger the fastenings for the sisters in the planks so you don't split them. Trying to cut the old ribs for a decent staggered scarf while standing on your head in the bilge will be a real pain for less strength.
Bob Cleek
posted 10-24-1999 01:35 AM
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Dale is right... just go for it! I wouldn't worry about trying to build a jig, not only is it an unecessary step which may result in error, while laminating in place is certain to be accurate, but you may well end up with a nice frame that you can't fit into the boat because of other stuff in the way. You will be better off sistering next to the old frame than trying to scarf in a repair. It is a devil of a job and not necessary. Most all older wooden boats with steamed frames have sisters and it isn't a black mark against them. They are stronger for it.
Evan Showell
posted 10-24-1999 08:49 AM
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Dale -- I appreciate the kick in the butt. I 'll admit to a tendency to overthink things, however, I will not have the weather, time or assistance to make the necessary repairs until the Spring. Thought with a jig I might laminate new frames in the basement over the Winter and be ready to go when the weather improves. I did consider sistering, but am edgy about the thought of introducing local hard spots in the hull which is reputed to be a result of sistering -- although I've never actually experienced the problem. I am familiar with sistering as the Tumlaren I have an interet in has several sistered frames. I'd prefer to avoid sisters on Puff if I can since the hull is mahogany finished bright and I'd prefer not to have the extra bungs visible from outside. I notice that some of the frames already have a graving/dutchmen repair which appears to have been riveted in place. I'm not looking for "museum quality" -- I just thought I'd survey the available knowledge before diving in with a particular repair method. As always, all advice is appreciated if not necessarily followed.
noquiklos
posted 10-24-1999 11:43 PM
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In my admittedly limited experiences, hard spots are more a result of sistering too late than anything else. My 65 year old Blanchard was raced hard through her "middle" age, and has been sistered from the partners, to mid-cockpit on every frame, as well as several twice. She is still tight, strong and sound, doesn't leak a drop, and embarrasses quite a few clorox bottles on occasion. Laminating sisters is easy fast and strong. Go for it.
John Engels
posted 10-25-1999 09:00 AM
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If you don't want the frame epoxied to the hull when you laminate in place, use a piece of poly / plastic (about 4 mil.) between the hull and the first laminate. When the frame is completely laminated, remove the plastic and attach the frame with your fasterer of choice.
MikeGardner
posted 10-25-1999 11:19 AM
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I know many have built laminated frames to replace cracked originals.The new laminated frame will be much stronger than the original bent one. Has anyone with these new lam frames noticed fastenings pulling out or cracks in adjacent frames following the repair? Does the increased stiffness of the new frame adversely affect the rest of them?
Just a thought I had...
Andrew Craig-Bennett
posted 10-25-1999 11:32 PM
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Ah, yes, laminated frame repairs! Can I chip in my two pennyworth here?
"Mirelle" was built in the classic English way, with grown frames every two feet and a pair of Canadian rock elm bent frames between each (Herreshoff would NOT have approved, and he would have been right!) with wrought iron floors on every frame. To add to the fun, the iron floors were bolted to the frames before the planks went on (now find the bolts....)
This was the standard method of building one off yachts in England, because, of course, it saved the cost, in materials and labour, of making moulds, onto which you put your ribbands, in order to bend your frames, before planking, only to throw away the moulds and ribbands later. You could take your grown frames straight off the mould loft floor, cut the bevels on the bandsaw, erect them, ribband up, steam the bent frames and plank up.
(Herreshoff, of course, faced with the cost of making complete jigs for his upside down building method, series built his boats in classes to recover the mould cost!)
The snag is that the CRE bent frames rot, given half a chance (why did we use that stuff, rather than our own perfectly good oak?) and, more seriously because the bent frames "give" more than the grown frames do, the grown frames are liable to crack every time the boat hits something hard.
The two rotten bent frames that she had when I bought her I have replaced with new oak frames, steamed in. There is enough space to get them in behind the beam shelf and stringer since, obviously, these lie on the grown frames.
After our 1987 hurricane, in which the boat was an insurance write off, the grown frames are progressively turning into laminated frames, along the length of the boat! The planks were originally attached to these with turned copper nails; a surveyor could tell the renewed frames, as these have clenches!
Yes, I have seen oak laminated with epoxy fail - not on my boat, but a set of deck beams on a nice Lyle Hess cutter built by a very good builder. However, since the laminations are through fastenened, as they would be on the Dragon, it does not bother me that much. In theory, I would now use resorcinol, and screw each layer one by one.