Sunday, February 24, 2013

Timeout Life...I Have A Boat To Build

I had to take some time out from life to spend with Summa. She was becoming jealous and I honestly do not blame her. I picked up where I left off and I must say that after a few hours in the garage with Summa and Philip Glass, I was in bliss.

I had to finish the doublers for the transom and bulkhead 2. I mixed up some epoxy and quickly bonded on the doublers.



After bulkhead 2 had cured, I cut the remaining upper section of the access hole (matching the upper contour). I left a small step around the access hole with the doubler to help properly seat the hatch.

I also finished laying out the transom doubler for the tiller hole and was able to prep that for bonding. For this doubler, I bonded together two scrap pieces of the 6mm plywood sheet. I will show a picture later after it has been bonded to the transom.

I was then ready to start the bottom panel scarf joint. This is somewhat of a milestone for me. It is also somewhat intimidating considering I only have two remaining sheets of 9mm and thus no room for error. I decided to try and 'freehand' the joint using a hand plane instead of using a powertool with a tool. I have seen this joint completed using a hand plane on a couple of other Navigator blogs and it looked straight forward. This is my first time to use a hand plane and what better time to learn than with a little applied pressure. 

The recommended taper ratio was 8:1. I marked it out and clamped the sheets together with an additional two sheets of 6mm to provide some additional support/stiffness.


I adjusted the plane and went to work. It was actually quite easy and seemed to be easy to control. I was afraid I would somehow gouge the plywood but I proceeded slowly and was able to create a nice taper.


The nice thing about working with plywood is that the layers aid you in remaining straight when scarfing the joint. I had about 70 percent of it complete after about 20 minutes. 


I then noticed a small gap in the center of the panel between the two sheets. You can see the gap in the below image. This was due to the slight curvature that developed from the way the plywood sat on the jig.


To remedy this I used a couple of 2x4's and clamps and was able to finish off the joint. I then used a finishing sander to smooth the two surfaces. 


I was now ready to bond the two together. I used epoxy with a silica thickener. This made the epoxy almost like a paste and I applied one layer across the joint. I will go back after this has cured and apply another layer to both the upper and lower bond lines.  


I placed one sheet on top of the other and took a quick pic showing the upper bond line. Not bad for a novice.


I then quickly covered the joint in wax paper and then applied pressure using a couple of sets of 2x4's and clamps. I screwed the bottom 2x4 to the jig to keep it level. The diagonal 2x4's and clamps required a little help from the wife to set up. Looking back I wish I had used a slightly smaller angle relative to the board normal to apply more pressure across the middle of the joint...hindsight is always 20x20.



I will let this cure and then apply another layer of epoxy/silica mix to the upper and lower bond line. After a little touch up sanding I should be ready to go....bliss.