To tab seams, or not to tab...

Hi all,


I've got about 90% of my Ches 16 stitched together right now(ran out of copper wire two feet from the stern), and am trying to decide how to proceed with fillets once I finish the stitching tomorrow.  I've read that some people tab the hull and then remove all the stitches before filetting.  This technique appeals to me, but I'm a little unsure as to how to go about doing it.  What type of mix to do you use: wood flour, cell-o-fill, etc?  How often do you apply tabs to the seams (between every stitch, every other?)?  Are there any downsides to this method?  

 Any advice/info would be great!   

5 replies:

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RE: To tab seams, or not to tab...

Here's how I did it on my WD12 (click on picture for larger image). It's the same thing I did on my wife's CH16LT.

I put a tab between each wire since the hull curved so strongly. The tabs were made from woodflour and epoxy/hardener mixed to a runny putty consistency. The mix was forced into the cracks, rather than being a bump on top of the wood. This is to allow the fillets to be small & smooth.

Let the tabs harden for at least 24 hours, 48 would be even better, before removing the wires (this is why this techniques is not used in the 1-week boatbuilding classes). Once the tabs are cured, they are plenty strong to hold the hull together while the filleting is done. Check out Building a Wood Duck 12 - Interior Fillets & Glass for more info. Good luck.



RE: To tab seams, or not to tab...

As always, Laszlo speaks with the voice of an angel!

I followed this process with my just-completed Shearwater 17, both on the hull and on the pre-assembled deck structure.   As I understand it, the tabbing (or welding or tacking) step is mainly taken so the builder can pull out the wire stitches, then complete the job with a final full-length over-fillet.   I found it easy to remove 95%+ of wires, leaving just a handful at the extreme ends of the craft.

If necessary to give that final sought-after very smooth fillet, you can quickly run some coarse sandpaper wrapped around a short length of broom handle along the cured tabs, just to tidy-up any little peaks or jags.

I went a half-step further (picking up on Laszlo's point about the consistency of the tabbing epoxy): I painted the chines (inside) with a thinned-out epoxy mix, to penetrate the cut edges of the ply that butt against each other, in turn leading to better penetration of the epoxy in the filletting material.   By no means essential, but it took only minutes and I though it had some merit.

Enjoy the rest of the build!



RE: To tab seams, or not to tab...

I'm planking a Northeaster Dory, and seal seams with unthickened MAS before applying fillets. I "seal" the interior seam with tape to prevent runthrough.


But "seal" is not accurate. I cannot find a masking tape or duct tape that will not release when in contact with fresh-mixed MAS. I have several paper masking tapes, and a really tenacious holding duct tape, but the duct tape is the worst for releasing contact when fresh MAS hits it, and that takes only a very small amount.

 Does anyone have experience with a brand other than 3M paper masking tape or Intertape Ploymer Group of Sarasota FL grey duct tape? By experience, I mean a good outcome in holding adhesion and resisting release when MAS applied.

 Denny Hugg

Gulfport, MS


RE: To tab seams, or not to tab...

Well, I went ahead and tabbed the seams yesterday.  Gave it about 30 hours to cure and started removing wires today.  So far, the boat has kept its shape without having panels pop off (I'll take that as a good sign).  I do have a bit of excess glue on the inside of the panels around the tabs due to using the wrong sized tool.  I'm going to smooth the seams themselves with Wordsmith's idea of a broomstick and sandpaper... should I also hit the inside panels with the random orbital to knock off the excess glue?  I'm thinking it may be worth the effort since I'm going to all the effort of smaller, cleaner fillets.  


Anyway, just wanted to give an update... so far, so good!   

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