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- Thread starter bluegrasslover
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crkdltr said:bluegrasslover said:I have a bad problem. One of the scarf joints on a rub rail came apart. The rub rail is glued to the sides so I can't really take it off and fix it. Luckily it did not break the side when it came apart. I used a couple of c-clamps to see if it would at least go back together and it's under a lot of outward pressure which probably means that trying to glue it will ever work. Glue and screws? Anyone else ever had this unfortunate problem? I'm really heartbroken right now. :cry:
Yes, it did the same for me. Do you have inwales and outwales? I just counter sunk a screw into the meatiest part of the scarf joint and screwed it down with liberal amounts of glue and applied as many clamps as I could. Since I painted my outwales I ended up doing the best I could, sanded anything that wouldn't stay down, applied a lot of wood putty, sanded smooth and painted.
I'm planning on adding some inwales but haven't yet.
Did you use epoxy on the joint or did you use some wood glue ?
How thick were the pieces that you scarfed together ? Looking at the picture and the wood for the side panels the rails look pretty thick to me and the thick wood does not like to bend or conform to the boat shape as well as thinner wood.
Your idea of some "C" Clamps and epoxy might cure the problem , if the wood will bend in like it should.
Chuck.
How thick were the pieces that you scarfed together ? Looking at the picture and the wood for the side panels the rails look pretty thick to me and the thick wood does not like to bend or conform to the boat shape as well as thinner wood.
Your idea of some "C" Clamps and epoxy might cure the problem , if the wood will bend in like it should.
Chuck.
If you clamp too tightly, or have too much weight sitting on it, an joint will get too much epoxy squeezed out and be a "glue starved" joint. IE: a weak joint. I did it once on the coaming of my first kayak and it popped off under duress.
oldsparkey said:Did you use epoxy on the joint or did you use some wood glue ?
How thick were the pieces that you scarfed together ? Looking at the picture and the wood for the side panels the rails look pretty thick to me and the thick wood does not like to bend or conform to the boat shape as well as thinner wood.
I used Gorilla glue for the scarfs and don't think I clamped it too tight but maybe I did. The wood is 3/4" as specified in the plans.
I was worried about the rails being "bendy" enough. I ran them through the planer. Took about 1/8" off, maybe a hair more. Down to about 5/8" think.bluegrasslover said:The wood is 3/4" as specified in the plans.
It's to late to say this but the only way to glue the joints together is with epoxy , it holds and is the only thing I use. On a rail that thick and with the bend in it , that is asking to much from the wood glue as you found out.
Chuck.
Chuck.
I used epoxy to reglue it. We'll see what happens. I've got some screws to put in as well once the epoxy has setup.
bluegrasslover said:I used epoxy to reglue it. We'll see what happens. I've got some screws to put in as well once the epoxy has setup.
Don't forget the idea one of the guys posted about laying a bit of cloth over the joint area to reinforce it. That might also help.
Were you able to get all of the residual glue out before you epoxied it?
I notice that you have the joint set up so that the adhesive is working in tension - that is, the bend in the wood is trying to pull the glued surfaces away from each other. I set mine up so that the adhesive is working in shear - that is, with the glued surfaces 90 degrees to the bend, so that the tension is trying to slide the glued surfaces past each other.
(another way of putting it - - you have your glue surfaces vertical, mine are horizontal. So the strain acts on them differently)
That seemed logical to me, but I honestly don't know which is best... anyone have an opinion?
Regarding glue starvation (which is what happens when you clamp the work so hard that all the glue is forced out of the joint) I always thicken the epoxy a bit when using it in an application where I'll be clamping it. As a matter of fact I thicken it for ANY application other than glass or saturation. Not nearly as much as I would for making a fillet, but some. I think that helps prevent all the epoxy from being forced out of the joint.
George
George,
Unfortunately, I wasn't really able to get any of the old glue out because there just wasn't enough space to get in there. I could barely get new glue in the space. Regarding the scarfs and tension...I know exactly what you're saying but as a first time builder that was something that never crossed my mind while I was scarfing the rails. Next time! If I can get this one fixed I think I'm going to go back and put a couple of screws in the other rail scarf joints just for piece of mind. Something I had thought of is this...if I just can't get this thing fixed I did make the sides 11" instead of 10" so if all else fails I guess I can cut off the rails and be left with 9.75" sides. That is, of course, .25" less than the plans call for but I would think it would be ok. And much better than starting over! This boat is going to be almost exclusively used in the 3 to 4 acre pond behind my house so it should be fine. All learning experiences for the next time.
Unfortunately, I wasn't really able to get any of the old glue out because there just wasn't enough space to get in there. I could barely get new glue in the space. Regarding the scarfs and tension...I know exactly what you're saying but as a first time builder that was something that never crossed my mind while I was scarfing the rails. Next time! If I can get this one fixed I think I'm going to go back and put a couple of screws in the other rail scarf joints just for piece of mind. Something I had thought of is this...if I just can't get this thing fixed I did make the sides 11" instead of 10" so if all else fails I guess I can cut off the rails and be left with 9.75" sides. That is, of course, .25" less than the plans call for but I would think it would be ok. And much better than starting over! This boat is going to be almost exclusively used in the 3 to 4 acre pond behind my house so it should be fine. All learning experiences for the next time.
I bet you'll get it fixed. A couple of screws to reinforce it once the epoxy has cured, maybe a little patch of glass cloth right where the joint is.
I used Gorilla Glue for some oars that I made to go with my rowboats. Laminated the shafts and blades with it. Seems to have worked ok, but of course there is no tension or bending in the oars, and they honestly have not been used that often.
All in all, I'm not sure the stuff offers anything that couldn't be done as well or better with epoxy. It is not inexpensive, clean-up is not particularly easy, and from what I hearing from you and Jack, it probably ain't as strong as epoxy. On top of everything else, once you open the bottle you can depend on a pretty short shelf life.
I do like the way it foams up and fills gaps, and of course you don't have to mix it. There are probably some good uses for it, but I don't keep any on hand. I have my left over epoxy, and I keep Titebond III for applications where epoxy seems like more trouble than it is worth.
George
I used Gorilla Glue for some oars that I made to go with my rowboats. Laminated the shafts and blades with it. Seems to have worked ok, but of course there is no tension or bending in the oars, and they honestly have not been used that often.
All in all, I'm not sure the stuff offers anything that couldn't be done as well or better with epoxy. It is not inexpensive, clean-up is not particularly easy, and from what I hearing from you and Jack, it probably ain't as strong as epoxy. On top of everything else, once you open the bottle you can depend on a pretty short shelf life.
I do like the way it foams up and fills gaps, and of course you don't have to mix it. There are probably some good uses for it, but I don't keep any on hand. I have my left over epoxy, and I keep Titebond III for applications where epoxy seems like more trouble than it is worth.
George
That stuff was responsible for the messiest work on my project. Just gluing some support blocks for the seat planks.....biggest dang mess!Kayak Jack said:A pox on Gorilla Glue. It ruined a project for me too.
The blocks kept sliding around and of course, the foamy excess when it set. Never again!
Blue Grass Lover, My inwhales are longer than my pieces of wood. A boat, in rough water, during landing and launching, and going over logs etc. has most stress in the very middle of the boat as it tries to bend so that end meets end, stretching the middle wider and wider. So, I put my longest piece centered, butted the end pieces, and epoxied on a reinforcing plate a few inches long on the butt joints. Though not as elegant as a successful scarf joint, I find reinforcing plates (aka scab patches) to be elegantly simple to do, (I need that) and robustly strong, (I need that too).
I was wondering, to open that joint up if you could saw down through the joint? That would both remove the old stuff and provide a clean surface. You'd want a saw with wide-set teeth to give a wide kerf, I think. Maybe some real carpenters on here can adjust that thought?
I was wondering, to open that joint up if you could saw down through the joint? That would both remove the old stuff and provide a clean surface. You'd want a saw with wide-set teeth to give a wide kerf, I think. Maybe some real carpenters on here can adjust that thought?
Kayak Jack said:I was wondering, to open that joint up if you could saw down through the joint? That would both remove the old stuff and provide a clean surface. You'd want a saw with wide-set teeth to give a wide kerf, I think. Maybe some real carpenters on here can adjust that thought?
That's a thought, if it comes to that.
You could also put some adhesive backed sandpaper on a putty knife and work that around in there (I think there would be room based on the photo I saw.
Hopefully what you've already done will fix it, though. In the photo it looked like there wasn't a whole lot of anything in the joint, which is what made me suspect that it was glue starved.
Jack suggested a reinforcing plate... that's a similar idea to the patch of fiberglass that someone suggested earlier. A strip of brass a few inches long with holes for screws, mounted on the outside of the curve where the tension is. If you worked it out carefully, it wouldn't look bad. But maybe the epoxy that you've already done and the screws that you are already planning will be enough.
George
GBinGA
Don't know if it'll decrease the pressure on the outwales, but it will definitely help distribute pressure while in use. I've been thinking about adding inwales too, but I haven't made that call yet.bluegrasslover said:Will adding inwales increase or decrease the pressure on the outwales?
Orienting the joint the other way would help (not now of course). Either way, the joint will have compressive forces on the inside and tension forces on the outside of the bend. Orienting the joint the other way would minimize the tension at the joint vs. the way it is oriented in the picture.gbinga said:That seemed logical to me, but I honestly don't know which is best... anyone have an opinion?
bluegrasslover said:Will adding inwales increase or decrease the pressure on the outwales?
That seems like a tough question to me, and an interesting one.
If nothing else, it would give you something solid to screw the rub rails to.
GBinGA
The outwales would still be bent the same amount, so I don't think that the pressure on them would change much at all. It might keep from concentrating any more pressure at that point sometime in the future.bluegrasslover said:Will adding inwales increase or decrease the pressure on the outwales?