Scarf or butt?

[smacrae]

Have just received my CS17 plans (#164).

Need to decide on scarfing the ply sheets or butt joining. I know there are pros and cons for each method. Any thoughts would be greatly appreciated.

With thanks.

Steve

[Norman Colter]

G'day Steve,

I'm building a different boat but was faced with the same question. After a lot of internal debate I chose to scarf.

I used the stairstep method described in Devlin's Boat Building. (A great resource) I made a couple passes with a power plane but felt much more comfortable with my trusted hand planes. Finished them with a belt sander.

Be real careful with orientation. When cutting, one is face up, while its mate is face down. The joints go from interior to exterior, fore to aft. I cut one end of six pieces to start, then the other end of two. I have since also scarfed the two bottom panels. Four pieces at once. It was easiest to do the six at once.

When glueing I used a full sheet at the bottom of the pile to help with alignment. Covered with plastic I made the joint in the middle of the sheet so i had four feet on either side to align to. Then I carefully checked the over all length to make sure my joint was perfect. Lay out another piece of plastic and do the other. Clamp well and leave for three days.

When I had both sides done I stacked them face to face and cut both at once. Before seperating them I transfered all the locations to the other side.

It wasn't as difficult as I expected. My sides and bottom have beautiful fair lines. Sighting along the sides leaves no notion of where the scarf is. No flat spots

Hope that helps. Have fun.

[Garry]

Scarfing is the way to go. It really isn't hard even if you have never done it before. I simply marked the sheets and stacked them in a stairstep fashion based on the length of the scarf. I clamped them together and added a few small finish nails to ensure nothing slipped.

Then I took my trusty belt sander and sanded down to the marks. The glue lines give excellent indication of how even your work is and you can tell where you need to go farther and where you need to ease up.

A little filler mixed with the resin will take care of any uneveness. When you clamp for gluing, make sure the clamp boards are wider than the scarf so the thickness is controlled by the unsanded material.

[PeterP]

G'Day Mate,

Seems to me you already decided to complicate your life by building your own boat. What's one more thing! Scarfs are a lot slower yet ten times more satisfying to do than butts. Do the scarfs for yourself and save the butts for when you go pro.

[Charlie Jones]

Hey!! I'm a pro builder and I use the scarfs. Much nicer looking to me.

Simple to do too. I use a hand power plane to rough them down then finish with a block plane, but a sharp bench plane makes quick work of them also.

Graham teaches classes on scarfing and he has students use a bench plane. Of course, then you MUST learn how to sharpen it, but you need to know that anyway.

[PeterP]

:shock: Sorry Mr Jones, No offence meant to you or any other pros out there. Peter

[Charlie Jones]

Non taken- see the smilies? I was just funning ya.

[PeterP]

Seriously, I think you want to be comfortable with both. I scarfed the bottom panels and the topsides in my boats because I find it is easier to fair scarfs and both both sides are visible. I did plywood butts for seats and decks or in places where the backer is not seen. Also, ply backer can add a lot of strenght to your panel. Think 1/4 in (6mm) plywood in the seat tops. In my first seventeen the seat tops ( with tape butts) proved a little too springy precisely where people invariably stepped into the boat. The seams were strong enough but a bit on the mushy side. So, the next boat got 10 in wide plywood backers (doubling the the thickness). Save you cutting in extra 1x2 in for support beams. Finally, my decks are clear coated so it's critical to have a super tight joints there, hence I do a butts in that area. Peter

[PAR]

Butted pieces need a backer (butt block) and some areas of the boat will not permit this, because of space limitations or aesthetic reasons. The butt joint is perfectly acceptable, easy and fast to complete. That said, I use scarfs almost exclusively. I use a sliding router jig, over adjustable, tapered ramps for most of my scarfs. I hit the stock with a power plane to get it close and then plow through with machine accuracy using a router. You can get similar results with hand tools, though it can be a chore if you have a lot of scarfs to do that day.

[smacrae]

Thanks everyone for your helpful replies.

It looks like I'll just have to get off my butt and start scarfing.

Steve

[Greg Luckett]

When scarfing planking I use a Makita power plane for the roughing, then switch to a Bosch belt sander to finish the scarf. I tend to use hand blocks for small pieces, but use a band saw to get close first. Using power tools is more unforgiving, but if I am careful, will save huge amounts of time.