backer boards for butt joint for Shearwater plans build

We are at th epoint where we need to joint the pieces we cut out for our Shearwater Sport plans built (do not ask me how ling we have been at this point, but it is time to start moving again). 

 

Simple question. Plan is to put packing tape on outside of each piece to catch any squeeze through. Slather up the end of each piece and than a portion of the inside and mount a backing board. Let set with pressure applied (weight or screws) and than wrap in fiberglass

Questions:

  • back board is needed right?
  • 1.5" on each side? or is their a science to this?
  • Should fiberblass be added after joint drys or while everything is wet?

jh


5 replies:

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RE: backer boards for butt joint for Shearwater plans build

   I am not sure what butt joints you are referring to.  I built my Shearwater Double from kit which uses puzzle joints.  I am pretty sure that plans builders use scarf and not butt joints.  I am on the road otherwise I would look at the plans for the answer.  When in doubt, call CLC.

RE: backer boards for butt joint for Shearwater plans build

puzzle and scarfs 1x4 wrapped in clear packing tape, with seran wrap on the floor. For true butt joints, the same thickness ply wood or fiberglass tape on both sides. More info, if you let us know what type of joint you are doing.   

RE: backer boards for butt joint for Shearwater plans build

Ok, so this is a build from plans. Not kit. So no puzzle joints unless I attempt them myself - but I'd do scarfs before trying that.

The plans say "butt joint here" or something similar where the two longer sections of each piece are joined. Right where the puzzle joints are with the kit. I am not sure I can do scarfs because the plans indicate butt joints and I think they are measured for that type of joint - where you lose no length. 

I can take a photos of this section of the plans to clarify. Or we can ask hypothetically - if one were to do a butt joint, is there a formular or best practice for how wide the backer plate should be?

 

 

RE: backer boards for butt joint for Shearwater plans build

   I did scarf joints for my NE dory before cutting the pieces. I am now building a Pygmy kayak and it uses butt joints with glass tape on both sides. I spoke with the owner of Pygmy a few years ago and he said they haven't had failures and have been doing it that way for years.  The puzzle joints ensure correct alignment of the pieces.  Barry

RE: backer boards for butt joint for Shearwater plans build

for butt joints, a layer of glass tape on the inside side of pieice aligned with the joint is all that you need at this stage to hold the sections together so that you can stitch up the deck and the hull.

once you stitch it together, the inside of the deck and the hull will get another layer of glass (which will go over the butt joint/glass tape).  and the outside will be glassed as well.

no tape is necessary on the outside of the butt joint...it will just make a bulge (so tap e ok on the inside....not ok on the outside).

it's basically the same technique for the shearwater with puzzle joints or the arctic hawk with butt joints or the old clc kits with scarf joints - tape on the inside only for getting the parts together.

h

 

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