Day 6

5/10/2012

Time to commit to the shape of the boat's deck and hull by tack welding the joints, however I don't want to permanently join the two halves together just yet.  

First I removed the temporary stitches and the shrink wrap and transferred the deck to another set of saw horses. 

To prevent the deck and hull from becoming prematurely permanently joined I covered all of the edges of the hull with masking tape including the forms and bulkhead.  This way and drips from the deck will not stick wood to wood.  I also covered the floor under the deck with a sheet of plastic to catch any drips there.


With the deck off I noticed that the hull had a lot of gaps betweeen panel edges especially along the keel line.  This was probably due to the copper stitches stretching over time.  Whatever the cause I needed to close those up so the tack welds and later the fillets won't drip out, so I flipped the hull upside down and tightened all of the loose stitches.  I also wanted to be sure that the bow and stern closed up tightly, so I applied a number clamps to both ends.  Some folded sand paper helps the clamps grip the angles better.





To tack weld the seams, I mixed epoxy resin and hardener with some wood flour (processed saw dust) to the consistency of ketchup.  Then that mixture is drawn up into a syringe and a bead is injected into all of the seams of the hull.  Its important to avoid tack welding the stitches or else it will be hard to remove them later.  Temporary forms were not tack welded, but the permanent bulkhead was.

It took a little practice to avoid creating big globs of goo so I used my gloved finger to try to smooth out the epoxy after it was applied.  Once the entire hull was finished I moved on to the deck.

Drawing up the thickened epoxy into a syringe can be difficult and is a little messy.  I used a shop rag to remove the excess epoxy from the end of the syringe before moving to the boat to avoid drips, but even then I still ended up with a few.

After both hull and deck had received their tack welds, I made fillets in the bow and stern.  Since both of these areas are narrow, it was impossible to get a syringe into them. Instead I mixed up some epoxy and wood flour to the consistency of peanut butter and then applied a smooth coating to those joints pressing it into place with a filleting tool (basically just small strip of plywood with rounded ends).


The wires in the bow and stern were covered by the fillets which will make getting them out more difficult.  It may be possible to heat them with a torch to loosen the epoxy, but if that doesn't work I can just clip them off and sand them down and it should not be noticeable.  For now I needed them to keep doing their jobs until the epoxy is fully cured.

With the tack welds and fillets in place it was time to attach the deck back to the hull so that everything cured with the right shape.  Before doing that, since I had fillets at both ends and since I still want to be able to remove the deck later, I decided it would be a good idea to apply some masking tape to the underside of the deck at the bow and stern.


This turned out to be a really good idea, because even with the tape hours later it took some effort to separate the nose of the deck from the hull.  Permanently attaching these two parts at this stage would have been a disaster.

Then I restitched the deck and hull together using a mix of copper stitches and shrink wrap.  You'll notice I used more shrink wrap this time.  Since this is shape the boat is going to take forever, I felt it was important to get it right.


After squeezing everything together I noticed a little epoxy oozing through the joints.  I assume this is some form of capillary action where the epoxy is soaking through the fibers of the wood. It tells me that I am getting a good tight bond between the panels, and once the entire boat gets sanded and coated with more layers of epoxy the dark spots  will be blended right in.  

I spent the next hour or so going over every joint of the boat making sure that the panels were aligned properly.  The easiest way I found to do this was to take a thin putty know and insert it between the panels, loosen the stitches on either side, wedge the panels into the proper form, then tighten the stitches and gently remove the putty knife.  Since I am using epoxy with a slow hardener I had time to do all of this before the epoxy was fully cured.

I also applied more clamps to the bow and stern to ensure that those panels lined up properly and there were no overlapping panels.

Here's a few shots of the interior of the cockpit with the take welds in place along the permanent bulkhead.
Here's one of the underside of the cockpit with the temporary spacers in place.

Next I'll be cutting in the hatch for the rear bulkhead access.

Total time on this phase: 3.5 hrs. 
Total time on construction: 16.5 hours

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