Cove & bead planks / strips.

Set up a circular saw through a bench and a simple chipboard jig
or better still a table saw if you already have one.
Takes about 5 seconds to cut a scarf
and on another bench I would glue up about 50 x 15m planks in one go for the next days planking.

 

Dont cheap out
Use epoxy, even a cheaper more industrial versions would adhere to timber better than poly or vinyl imho.
Many has been the repair over the years replacing timber in production boats where they used poly and vinyl, but I have probably only done 1 or 2 timber repairs on epoxy boats and they would have been poor installation of fittings, not build or adhesion issue's

 

Sounds like quite the risk taken for so little effort in scarfing

 

There is no risk in butting strips, assuming it's a modern interpretation of the method (sheathings). Scarfing does help align strips and a simple circular saw box, at the appropriate angle can cut several strips at once.

 

decided

I'm going to build something like a salmon wherry. the hull shape is comprised of gentle curves and should plank easily. I did a skin on frame hull that i will use to get the lines off of. Sounds like square edge strips glued with Tite Bond 3 then epoxy and cloth using one layer on the inside and cloth, mat, cloth on the outside followed with Pettit Easy Poxy one part paint. Thanks to all for the advice. Build will start next summer

 

For once I agree with Gonzo.

Scarfing to continue one plank is painful and a waste of time.
I just made a square cut on both planks, forced them to match with plane / sandpaper / file, then end glued with Titebond2. I did find that I needed to use scraps clamped along the length of the strips to keep the curve fair and tight. 3" scrap strips, packing tape enclosed for a release, clamped inside and out with small spring clamps.

It got to be so automatic I didn't even think about it.

I have also given up on cove and bead, square edge is easy, faster over all. I am thinking about not making the rolling bevels and just fill the gaps with sawdust filled epoxy after stripping the entire hull.

Marc

 

Be careful about using TiteBond II. It's not waterproof, not even close. It's also not a very strong adhesive without high clamping pressures. If you have gaps you'll be filling with thickened epoxy, you could also have adhesion issues, which is typical of all PVA's. Lastly, the reason none of the PVA style glues can be considered a structural material is creep. This is the permanent deformation of the glue under load over time. This coupled with "thermal plasticity" which can easily be a problem with darker, brightly finished woods in direct sunshine, force me to avoid the PVA's in many situations.

Now I know, a lot of canoes and kayaks are stripped with, PVA buttered planks and skinned with fabric, but these are fairly lightly loaded things. With strip planked joints, if they are are reasonably well staggered, the whole area acts like a finger joint which is perfectly acceptable.

 

Big fan of Gorilla Glue for this process. It's a polyurethane based glue, and it expands about 4 times as it dries so it will tend to fill any little gaps (and some fairly big ones). It's also totally waterproof and gets along fine with epoxy.

Titebond makes a black polyurethane glue, but I've not gotten good results with it.

As for the bead and cove or not argument, I didn't on my current boat and plan to on my next one. I'm picky about using recycled (read free or cheap) materials as much as possible and so materials cost is less of an issue for me, whereas the reduced fairing necessary is attractive.

 

I went through several scarfing jig designs until I got a bench sander and discovered the disc cuts a scarf faster and more accurately than any other tool. A glueing jig is worth having; with that I find joining two strips takes much less time than ripping and thickness planing them. A properly made scarf joint is as strong as the wood.

However, if you can get butted ends to line up and in the end it will all be wrapped up in glass and epoxy, then I agree there is no need to scarf. Does it really matter which glue was used to temporarily hold the parts together before it is encapsulated? I'd look for one that is easy to sand.

Gorilla Glue is fine if it is not able to expand, once it expands it is not a good adhesive and there are better and cheaper fillers. I would prefer a glue that pulled joints together to one that pushes them apart . . .

 

under what class is gorilla glue

it is better to scarf thicker planks
cove and round was designed to cope with frame bevels

 

Gorilla glue is a polyurthane.

Scarfs aren't necessary, in strip planking, so long as the butts are fairly widely spread out, which forms big finger joints.

On small craft, I'f never found butt joint alignment an issue. In particularly quick bend areas, I tend to avoid joints when possible. When I can't, I use a backer or jig to keep the alignment until everything sets up.

Not so long ago I was doing a larger strip plank job with 1.5" by .75" strips. They were edge set quite a bit, though butt joints throughout. The stiffness of the material (SYP) forced the use of clamp on backers (strips of plywood) to maintain alignment.

 

Technische Kommission Holzklebstoffe (TKH) class D4 says:

"Interior use with frequent heavy exposure to
drain-off water or condensation.
Exterior use, exposed to weather factors but
with adequate surface protection."

 

Sounds like you spent more time and effort than I did with my scarf cut with a cheap compound mitre saw .
No planing, sanding or filling required as you have a perfect cut every time.

I was doing 3 joints to make a single 15-16 metre planks doing 30 at a time
Took about an hour and a half for one guy to cut and glue (epoxy) so they were ready for the next mornings planking

 

Sabahcat,

Try it you'll like it.

All I was talking about was insuring the ends matched. Lets not get carried away with what you want it to mean.

It took 30 seconds to insure the boards matched. It took longer to write this response.

We are obviously talking about different kinds of boats since I was doing an 18' kayak out of 1/4 x 3/4 cedar.

Why didn't you make a single 4 x4 (size is just an example) scarfed board 15M long then cut to plank size. Any flaws on the surface will be gone after the reducing the boards.

There actually are lots of different useful ways to make long boards and the "best" way depends upon the situation.

Actually I did it your way for an earlier boat and it took significantly longer. Probably just my lack of skill, don't you think?

Marc

 

Found a photo of my scarfing jig that I used for cutting the strips for ther Raptor. As you can see it's just a couple of bits of 1x4 screwed to a piece of plywood at an angle. I fed a bunch of strips in on their sides so the ends were up against the stop piese, chopped them, flipped the whole bunch over, repeated, and viola, quick, consistent scarfs. Based on my experience the ease of matching up the scarfed ends is worth the little bit of extra time it takes to cut them.