Frame replacement/repair?

[W8EJO]

In the photo below you see a frame which has come unglued from the hull but has also begun to severely delaminate.

My questions are:
1) Is repairing a delaminated frame worth the time/effort or
2) Do I need a frame here at all? Its the center frame (of 3) on a 16' boat.
3) If I must repair/replace it, am I better off to replace it with a one piece plywood frame rather than building up another laminated frame?

Thanks

Terry O.

[Todd D]

Re: Frame replacement/repair?

Given that the hull has already changed shape since breaking free of the frame, I think you need it. It doesn't look like the frame itself is damaged, so you don't need to replace it. I would remove it, clean the frame and hull up and then glue the frame back in with a few screws from the outside to hold it inplace while the epoxy sets. It is not a time consuming or difficult job. It shouldn't take more than a couple of hours once you finally get to it. Use your Fein Multimaster (or knockoff) to cut through any spots where the frame isn't already separated from the hull and you will get it out cleanly. Glue it back in with west system epoxy thickened with 403 microfibers.

[TerryLL]

Re: Frame replacement/repair?

This frame looks to be in good shape. The only problem I see is a failure of the glue joint. The best repair here would be to remove the entire frame without damaging it, then clean all the surfaces and glue it back in the same place. A few fasteners through the planking can be used to full everything back together. Saving this frame will be a lot less work than building a new laminated frame.

This frame is an important structural member and needs to be where it is.

Edited to add:
Cross post, what Todd said.

[wizbang 13]

Re: Frame replacement/repair?

Finishing this boat, I would remove it,carefully, as not to rip up the ply where it is still sticking. pop in a temp spreader beam, then laminate ( by sandwiching the ply with 2 -4 lams of thin wood) a rail (fore n aft)about 2" total thickness. (this would mean notching out the other frames for the inside rail lams.) Then probably replace it, notched.
The frames are quite a bit oversized, but somebody did a lotta work on them, (30 lams of 1/16"!) so ,kind of a shame to pitch them. on the other hand, if the boat needs to be light weight, say adios to it .
A laminated rail is a better way to stiffen up a ply boat. 3 super stiff frames are just gonna make hard spots.
The CB casing will want a frame or two, but they can be tapered to a smaller dimension as they go up.
Do use 403 for all strength building.

[Canoeyawl]

Re: Frame replacement/repair?

My concern would be why did it fail? Is it glue starvation (over clamping), a poor batch of glue or some unintended shock load?
This repair looks straight forward, just reglue it.
But there is an argument for fasteners here.
Myself, I like 'em

[Thorne]

Re: Frame replacement/repair?

I agree, clean out the joint, drill for fasteners, pump glue in and clamp, then fasten with SS or SB wood screws from the outside. The fasteners may provide enough strength to avoid the glue failing again.

[W8EJO]

Re: Frame replacement/repair?

Thanks to all who replied.

What length/size screws would be appropriate? Is stainless steel better than brass?

[Todd D]

Re: Frame replacement/repair?

The length of screw to use dpends on the depth of the frames and the thickness of the plywood. I would probably use #12 x 1-1/2" bronze screws. If the boat will not be left in the water for more than a day or two at a time you could use stainless steel. Under no circumstances would I use brass screws. I would use a fairly large screw size so that you will have a bit of screw head diameter bearing on the plywood. Is the exterior of the hull painted or varnished? If it is varnished you might want to use #10 screws so you can use 3/8" bungs (#12 screws need a 1/2" bung). You can get away with two screws on the narower planks and 3 on the wider planks. When putting the screws in I would start at the bottom and work up. I would also clamp the top plank in place prior to putting any screws in.

[Canoeyawl]

Re: Frame replacement/repair?

Again, try to study why it failed. Is the rest of the boat about to fail in the same catastrophic manner?

The size of the fasteners would be determined by the molded thickness of that frame. You don't want to weaken it. What is the frame size?
The outside should not be bunged in my opinion, just a very shallow countersink will do it, with enough fairing compound/putty to just cover the head of the screw. Thats the nature of plywood boat building (to maximise on what little plywood thickness there is). The plywood can be reinforced with a bit of epoxy in the countersink - let it soak into the ply and harden before you proceed to fasten. Use varnish to bed the screw holes and finally wax on the screw for the last step.
A glued on rub-rail or out-whale will stiffen up the hull and give you a place for at least one through fastener. (Glued on with lots of clamps, a rivet through each frame plank and rail, and some screws in the field)

[wizbang 13]

Re: Frame replacement/repair?

This boat is what, 1/4 " thick ply? Filet and tape joints? The frames are out of proportion huge.
The whole boat does not need a SINGLE permanent fastening.

[Thorne]

Re: Frame replacement/repair?

Unless the joint failure is caused by sheer forces -- from bracing feet on the frame while rowing, or ? In that case fasteners can certainly help.

But overall I'm a fan of glued lapestrake construction, with as few holes in the ply as possible.

[Cuyahoga Chuck]

Re: Frame replacement/repair?

I'm curious about what the entire boat looks like. What holds all the joints together?
If it is Stitch & Glue all the frames and joints would have fiberglass-taped seams. If the hull is only ¼" thick screws are not going to have much for the heads to grip unless there are a lot of them. S&G hulls can live long and well because they don't have breaches in their skins for fasteners. If the epoxy joint under the bulkhead is not substancial enough I would bite the bullet and fillet and tape both sides. The tape would also reinforce the laminates in the bulkhead.
If I am wrong about the style of construction of this hull I apologize for the digression.

[W8EJO]

Re: Frame replacement/repair?

Here's a view of the boat:



Its a 16 footer. Frames are about inch & a half wide & about 2 1/2" deep You can see that several of the frames have come unglued.

I doubt its from rowing fatigue as the boat was never in the water. previous owner said it was due to improper outside storage over several years.

[Canoeyawl]

Re: Frame replacement/repair?

Unlikely that storage was the problem.
If I was to guess, perhaps the frames were installed after a coat or two of epoxy applied inside the hull without mechanically removing the amine blush and or abrading a bit of "tooth" in the joints.

Again an argument for fasteners if there ever was one. Once a glue joint is sheared, whats to keep the boat from just "unzipping"? Luck? That's not good enough for me, but I can only swin a mile or two... and I would hate to think of someone else's children swimming at sea.

A lot of plywood boats were built before "epoxy" (I've done it) and they always relied on fasteners to hold the skin to the frames. The technique varies little from traditional boat building techniques. Fit the parts, fasten them together. If you can use epoxy resin as a glue and eliminate some of the fussy variables of resourcinal glue so much the better.

[Cuyahoga Chuck]

Re: Frame replacement/repair?

Now we're getting somewhere.
Looks like a dynamite design. Hope you can set it right.
If the bulkheads tore loose without peeling some of the veneer off the plywood it may have been just a faulty epoxy joint.
I'm not familiar with this type of construction. What I do know is that a conventional S&G hull of this size would have 3/8" plywood bulkheads taped on both sides with 4" fiberglass. So the amount of surface for glued attachment would be much more than what you have. I don't want to suggest that your bulkheads are lacking glued surface. I don't know that.
One other thing, there doesn't seem to be a rubrail to stiffen the hull between the bulkheads. The distance between the bulkheads seems long enough to allow for a bit of flexing. Particularly where that oarlock is mounted. And, the leftside gunnal seems to be a little wavey altho' that may be a photographic illusion.