quick scarf joint & sheer clamp questions

I've just begun building a 16LT, and this is my first post to a forum on which I've long been a lurker. Thanks in advance for your tolerance of what I'm sure will be ongoing, silly questions! To get started:

1) How "clean" must the scarf joints be? In assembling the pieces for the hull, I've achieved good, strong joints w/ minimal epoxy seep (I used tape to protect the areas around the joint). But, at each joint there is perhaps a 1/16-inch bead of epoxy that, although I've sanded them down until they're flush w/ the wood, still create a color variation to the rest of the panels. Am I correct in thinking (hoping) that once the hull is glassed/epoxied/sanded/varnished these color variations on the scarf joints will not be noticeable in the finished product? If not, what's the remedy?

2) Why, with a 16LT (~15' 8" boat), was I given sheer clamps that when assempled = 18ft? I just trim these after assembly and installation to the correct length, right?

Many thanks for your expertise and patience. I'll be vsititing aain soon, I'm sure!

Kind regards, John

8 replies:

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RE: quick scarf joint & sheer clamp questions


I am building a Mill Creek 16.5 and I have also built the Passagemaker. The epoxy 'soak' at the scarf joints will disappear when the rest is coated with unthickened epoxy. The Shear clamps, according to my Mill Creek manual, are long to enable you to trim the ends easily where the meet at the bow and stern.

Regards, Alan

RE: quick scarf joint & sheer clamp questions

It sounds like you made a nice clean scarf joint - something that is not easy to do. That 1/16" line will show up dark, though, as will any other kind of joint you might make. My opinion and practice is that plywood should always be painted, which is one way to hide the joints.

RE: quick scarf joint & sheer clamp questions

I have scarf joints, I had epoxy seep on the joints, sanded them down, and stained them again.  Now that they're glassed, I can hardly notice the scarfs.   Esp. the darker stain (mine is two-toned)  The boat is looking really nice.  I've got to fill the weave one more time and sand it down, then do the hull.  My carpenter friend Dave made the scarf joints for me.  He stayed with the puzzle joints, and he is going to paint his.  But I think mine looks really nice.  And like I said, the scarf joints look great. 

RE: quick scarf joint & sheer clamp questions

Many thanks, gents, for your input; I very much appreciate it. The majority of you (thus far) seem to think that the joints won't be an aesthetic concern after glassing/varnishing, and that's a relief to me.


Although I appreciate that painting the hull would totally hide the joints, I really am determined to varnish in order not to mask the beauty of the wood.


Thanks again,


RE: quick scarf joint & sheer clamp questions


For scarfing wood-to-wood joints you probably used a thickener.  I used the silica equivalent shipped by CLC as part of the kit.  The thickened epoxy does have a color that will show through the glass if you do not remove it by sanding. It will apear white if thickened with silica or brown if thickened with wood flour.  The thickening agent, however, remains on the joint surface and does not soak into the wood.  So, as mentioned above, any epoxy that soaked into the wood will not be a problem but make sure that all of the "squeeze out" glue has been sanded away.


RE: quick scarf joint & sheer clamp questions

Thank you, Tim. Will do.



RE: quick scarf joint & sheer clamp questions

This is my first time building a boat and I got a little nervous when I uncovered the dried scarf joints and found quite a bit of epoxy overflow. I am using 120 grit sandpaper to sand the dried epoxy overflow from the scarf joints on my Chesapeake Double. 

I just want to make sure that I don't sand too much.  The joint is now sanded completely smooth, but there is some remaining epoxy that I could continue to sand off, but I don't want to "take away" too much of the plywood and make a depression at the joint.

This forum gives conflicting advice on whether or not the epoxy (plus silica) will show up in the final varnishing.  I will let you know how mine turns out.  I am only going to sand the epoxy smooth at the joints, not competely remove it.


RE: quick scarf joint & sheer clamp questions

One comment: I've found scrapers (I bought the ones sold by CLC) to be great for removing epoxy on joints, drips, etc. Much more controlled than sand paper--you can shave off the epoxy without sanding down the wood around it.

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