Cleanliness of scarf joints

Hi Folks...

I'm a few hours into a Wood Duck 12 hybrid from plans, my first boat.  I'm reasonably handy but have never done any sort of precision/high-quality woodwork.  I've done my first scarf joint, by hand with a plane, and now I'm working on a jig to make the others come out better.  I'll figure that out I'm sure, but one question resulting from my first scarf is, how clean does the epoxy job have to be to provide a nice finish when all is said and done?  Assuming I had a nice straight scarf (which I don't,) I would still expect to have at least a line of epoxy visible.  Will this show up through the glass, epoxy, and varnish that will cover the boat?  For a clean final finish, should I see nothing but wood at the joint?


Compounding the problem of visible epoxy at the joint is the fact that I thickened it with wood flour, so it has a nice dark peanut butter color compared to the light okoume.  Should I have not thickened, or thickened with something else?


When I started this project I resolved to not become paralyzed by details, and just build the damn thing.  So I'm not exactly worried about these joints, just wondering the best approach for the remainder (I also expect to have enough wood to discard one half of my ugly first scarf and give it another go with a fresh piece.)


Thanks for any help you might be able to provide....



4 replies:

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RE: Cleanliness of scarf joints


I didn't use scarf-joints, instead I used a 45 degree "scarf" joint, glassed on the inside of the boat with two layers of glass.  The joint worked very well, but left a line on the outside of my hull, similar to what you describe.  My solution is to paint the hull bottom a solid color, with a stripe at the side joint.  But at each scarf joint I'm putting a forward-slanting painted stripe from bottom to deck that'll hide the scarf (otherwise, the sides will be wood/varnished).  It'll give the boat a "racey" design (I think) and hide those annoying glue joints.  Other than that, you'd have to almost use a router with a jig to get a perfect "scarf," then glue it together with almost no error in alignment.  I prefer my method, a forward slanting "stripe" connecting the bottome to the deck, covering the joints in the middle of the boat.  The end of the boat (stern) will be painted far enough forward to cover that joint (about 16 inches from the stern) with a matching forward slant, and I'll put a similar slant at the bow, just for asthetics.  Like they say, if you can't hide it, decorate it!  I'll be posting pictures, when I get there.

 Good luck,



RE: Cleanliness of scarf joints

Larry's idea is a good one. I took my latest boat one step further and painted the entire hull. It really sets off the varnished strip deck and covers that awful scar at the scarf joint. I'm now convinced that plywood should always be painted, with the possible exception of the Shearwater and Wood Duck decks. You can see a photo of my boat at the end of my kayak blog:

RE: Cleanliness of scarf joints

Link to a scarf joint jig if interested.  The way I look at it, you can either spend a few hours practicing with a block plane or use the time to build a jig and get it right everytime.

I used only colloidal silica as a thickener for gluing applications.  The colour is cloudy clear so any excess (if the the area as not masked) does not stand out on a bright finish.

RE: Cleanliness of scarf joints

Many thanks for the responses.


Chris, I think your last sentence is just what I was looking for.  It's more of an expoy question than a scarfing question.


Twofoot...I had checked out your page before, but didn't realize the hull was painted.  Beautiful boat!  And Larry I've been watching yours too.



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