Assuming this is the joining technique and not some new "position" that I'm too old to understand, why are you scarfing ply vs the recommended glass backed butt joint?cracked_ribs wrote: ↑Wed Nov 11, 2020 11:51 am it was actually her idea to do the scarfing in the bedroom
At last a build thread: CR16 skiff
- Jaysen
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Re: At last a build thread: CR16 skiff
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Re: At last a build thread: CR16 skiff
For one, scarfs are easy so no reason to avoid them. For another I find they usually remain more fair than butt joints - the scarf seems to more closely replicate the bend properties of the wood on either side of the joint. Fairing sucks and getting everything to lay well is a lot more appealing to me than avoiding a scarf.
The only reason I think people use anything else is that the scarf seems to intimidate a lot of builders; Jacques designs in butt blocks etc to avoid that for people. But scarfing plywood is easy and I've never seen the need to work around it. In this case I may use a combination of methods on the chine panels just because the curvature near the transom is so slight that I don't think I'll pay much of a fairing penalty for doing it the easy way. So the second join in the chine panel, I may just butt splice for the sake of convenience.
The only reason I think people use anything else is that the scarf seems to intimidate a lot of builders; Jacques designs in butt blocks etc to avoid that for people. But scarfing plywood is easy and I've never seen the need to work around it. In this case I may use a combination of methods on the chine panels just because the curvature near the transom is so slight that I don't think I'll pay much of a fairing penalty for doing it the easy way. So the second join in the chine panel, I may just butt splice for the sake of convenience.
- gstanfield
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Re: At last a build thread: CR16 skiff
Scarfs are easy, I agree. I will say that there are a few benefits to butt joints though.
They are easier than scarfs (easy vs easier)
They make more use of the plywood, no losses due to scarf overlap. This can be a big deal on some designs, especially those that barely fit on X amount of sheets.
They are a bit quicker
It’s easier to visually verify a good fiberglass butt joint vs a scarf since you can see through the glass and know that you don’t have voids.
I’ve built a few boats using more traditional building methods and always scarf my boards and one scarfed all the plywood. I’m not opposed to scarfs, just pointing out that there are benefits and downsides to both methods depending on the design and the builder. On another designer’s website there’s a scarfing tutorial that I wrote along with photos of the process.
They are easier than scarfs (easy vs easier)
They make more use of the plywood, no losses due to scarf overlap. This can be a big deal on some designs, especially those that barely fit on X amount of sheets.
They are a bit quicker
It’s easier to visually verify a good fiberglass butt joint vs a scarf since you can see through the glass and know that you don’t have voids.
I’ve built a few boats using more traditional building methods and always scarf my boards and one scarfed all the plywood. I’m not opposed to scarfs, just pointing out that there are benefits and downsides to both methods depending on the design and the builder. On another designer’s website there’s a scarfing tutorial that I wrote along with photos of the process.
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Re: At last a build thread: CR16 skiff
I definitely would not argue with any of that... it's also worth pointing out that unlike me, guys like Jacques and Evan know exactly where strength is necessary and design to an actual spec. They choose the joins they do for good reason.
I'm more like a completely unknown, unsuccessful Renn Tolman with zero track record: I'm some dude with a pencil and a saw. Would a glass splice be adequate for the core? Probably. Am I going to engineer it and know that to be true? Hell no. I'll just scarf it and know empirically that it's plenty skookum.
I'm more like a completely unknown, unsuccessful Renn Tolman with zero track record: I'm some dude with a pencil and a saw. Would a glass splice be adequate for the core? Probably. Am I going to engineer it and know that to be true? Hell no. I'll just scarf it and know empirically that it's plenty skookum.
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Re: At last a build thread: CR16 skiff
To be clear, I wasn’t saying you shouldn’t scarf or trying to down your choice. I was just adding to the discussion with a few thoughts.
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Re: At last a build thread: CR16 skiff
No, I didn't take it that way at all. Lots of ways to skin this cat, and most of my decisions are legitimately questionable anyway.
- gstanfield
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Re: At last a build thread: CR16 skiff
I can definitely relate to that!cracked_ribs wrote: ↑Wed Nov 11, 2020 7:36 pm ... most of my decisions are legitimately questionable anyway.
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Re: At last a build thread: CR16 skiff
Today was overcast but not rainy so I dragged the plywood out onto the deck and beveled it for the controversial scarf joints!
That's most of what I got done today, but it's slightly fiddly work and I had to do a fair bit of cleanup afterwards so it ate up a big chunk of my day.
I started off by mounting a router on a piece of leftover hardwood flooring...I just punched a hole through the center and then countersunk a couple of machine screws using the router itself.
That let me bulk off the majority of the wood just by clamping a couple of straight boards to either end of the wood.
The areas I couldn't hit with the router, I knocked down with a plane until they were roughly in shape, and then fine-tuned it all with an orbital sander. I don't like to overthink this stuff, I just get it into shape and let the glue do the work after this.
I kind of like the look of the multi-toned plane curls.
That's most of what I got done today, but it's slightly fiddly work and I had to do a fair bit of cleanup afterwards so it ate up a big chunk of my day.
I started off by mounting a router on a piece of leftover hardwood flooring...I just punched a hole through the center and then countersunk a couple of machine screws using the router itself.
That let me bulk off the majority of the wood just by clamping a couple of straight boards to either end of the wood.
The areas I couldn't hit with the router, I knocked down with a plane until they were roughly in shape, and then fine-tuned it all with an orbital sander. I don't like to overthink this stuff, I just get it into shape and let the glue do the work after this.
I kind of like the look of the multi-toned plane curls.
Re: At last a build thread: CR16 skiff
Beautiful work and I don’t like scarfs!!!! Jeff
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Re: At last a build thread: CR16 skiff
Thank you very much - it's a bit hypnotic to do; lots of people hate them but I kind of enjoy it, in a way.
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