Dynel, Cleats, and Building Jig

Since last update I applied dynel fabric to the leading edge and bottom of the rudder and centerboard.  Dynel is reputed to have very good abrasion resistance, and I put several layers on the parts that will drag first when the water gets thin.  Shown here is the front corner of the centerboard.

I also cut, planed, and routed some stock for cleats to reinforce the joints where plywood pieces meet in the boat.  These are just plain pine boards from Menards.  I've got 80' prepared.  There are some knots in this #2 lumber, but I will just cut around those and work with the clear wood.  Yellow cedar is recommended, but not to be found around here.  I will precoat these pieces with three coats of epoxy on the sides that will not be glued to other pieces.

Then I got started assembling the building jig.  I set up the legs and started gathering pieces, 

And held them in place with some clamps, 

And spent quite a bit of time shimming and checking for level both lengthwise and crosswise.

Then I screwed the bottom to the legs, and screwed in cleats to hold the sides to the bottom.  It stiffened up very nicely and now feels sturdy.

And ended the night by placing the first boat part on the jig - the hull bottom.  I think the shop is going to start feeling pretty small soon...

Rudder/centerboard work and more puzzle joints

Since last update I have been epoxy coating and sanding more parts, and am running out of those.  I've been finishing up the rudder and centerboard by adding  fiberglass cloth to the trailing edges and the top edges.

Then I got a little carried away and started applying epoxy mixed for fairing, but just realized while writing this I haven't put on the dynel cloth on the front edges, so will need to backtrack a bit on that.

I also glued up the puzzle joints in the deck side pieces tonight.  One more puzzle joint glue up to go, where these side pieces are joined to the front piece.  I plan to do that before assembling the jig for the boat, which will take up a lot of my workspace.

Cleanup

Spent a little time today trimming off the excess fiberglass and feathering in the overlap, photos below.  I need to check with the SCAMP community regarding a couple things.

First, I wonder if there is any reason to keep areas like this square?

I'm thinking of putting about 1/4" round over on there and then fiberglassing the edge.

Secondly, I thought I was done applying glass on these parts (other than doubling up the edges), but then I saw a couple references today to other builders putting on two layers of fiberglass.  I reviewed the build manual and didn't see reference to that there, so not sure where that came from.

Rudder and centerboard fiberglassing

The rudder and centerboard glue-up turned out great.  I spent some time cleaning up glue squeeze-out and making sure all the surfaces were rounded off to the extent I thought right, and then decided to go ahead and put the fiberglass on.

Since the entire sides of the parts get fiberglass, and the cloth is to wrap around the leading edges, I wondered how to hold the parts while I applied the cloth and epoxy.  I decided to put a couple dowels in a stick of wood that would match up with the holes in the parts.  Then I could put the stick in the vise and have unobstructed access to one side at a time.

Here's the rudder ready to go.  Since this part was light I was not too worried about the strength of my fixture.

The centerboard was a different story.  There's about 22 lbs of lead in the board, and it's all hanging out at the far end.  Kinda scary - I wondered if I'd be able to cantilever that out.  I used a 5/8 wooden dowel in the big hole, and a steel pin in the small hole.  And I had to triangulate the stick with a brace against the bench so the whole works would not twist in the vise.  Seemed to hold OK for this job.

Holding the parts like this worked out well.  I had access to the entire side, and could work the far side where the fiberglass wrapped around.  

Here's the rudder with the fiberglass wet out.  The white patch is some fairing compound (epoxy and glass microballoons) showing through the cloth.

Today, after the first sides were cured, I trimmed the excess fiberglass off, and feathered in the edge of the cloth that would be covered when applying glass to the second side.  Here I'm using a utility knife blade as a scraper, and that worked very well.  This is a tip from Howard Rice on the SCAMP forum.  

After getting the parts cleaned up, I reversed the holding jigs and applied cloth to the other sides.

Rudder and centerboard lamination

I decided it was time to get the rudder and centerboard pieces assembled, so I spread glue on the mating faces, using a notched spreader to distribute the epoxy across the surface.

 Then applied clamps until I had squeeze out all along the seam.

Here's a shot of the centerboard clamping.  It takes a lot of clamps!  At the far end of the table you can catch a glimpse of my 23 gauge pin nailer.  After I slid the halves around until they were in alignment I shot a few 1" stainless pins in to keep the parts from sliding around while clamping pressure was applied.  That worked well.

I've also glued up the puzzle joint in the cockpit sole, and have been busy epoxy coating all the major parts of the boat that would need it sooner or later.  Sole, sole doubler, deck parts, transom cap.  I'm running out of parts, so that's good.  It will be nice to have them all ready to go at assembly time.

Thinking about the jig

I've continued to work on the boat and thought I was getting close to starting to put some more pieces together, which means it was time to gather the jig parts and see how those fit together.

Looks like all the pieces are there.

But then I realized I didn't have lumber on hand for cleats to hold the parts together or for building legs to get the jig up off the floor to make it easier to work on the boat.  

So, I made a trip to Menards for some lumber.  I ripped some 2x4s into 2x2s for the cleats, and built some legs out of 2x6 stock.  In this photo they are stacked two high.

But at this point I reconsidered assembling the building jig right away.  I realized that it would replace my temporary bench in the best work area, and there were still some more pieces that need to be epoxy coated sooner or later, so I decided to do some more of that.  

Here the inside of the cabin roof and sides are coated.  I'm also doing the seats, cockpit sole, and sole doubler.

It's pretty comfortable working in the shop with a good fire in the stove.

More centerboard weight

Before I glued in the centerboard weights I put them on the scale to see how far off my target of 22 lbs I ended up.  I found they weighed 20 1/4 lbs, which was not too far off.  However, I decided that at this stage I could easily get closer than that, and by doing so I wouldn't always have a nagging feeling that I was a little light in the centerboard!

I had gathered up a bunch of the lead shavings from the initial machining (see one of the first posts in this blog), and I melted those down with a propane torch and a little cast iron ladle I picked up at an antique store once.

I drilled two test holes with Forstner bits, 3/4" and 1", and filled them with lead.  I then weighed the slugs and calculated how many I would need to make up the 1 3/4 lb deficit.  I ended up needing about 20 of the larger size, so I drilled 10 holes in each of  the two halves of the centerboard to a depth of about 5/16".

And poured them full of lead.  I had shavings enough for only about half the job, so I melted the remainder off of one of my leftover ingots by putting it in the flame and catching the drips in the ladle.  That worked out smoother than I expected.

One job for tomorrow is to scrape these down to level, and then these halves will be ready for assembly.

Graphite pinholes, centerboard fairing and weights

I had noticed as I had been coating the inside of the centerboard case parts with epoxy thickened with graphite that there were some places that weren't taking the epoxy.  I don't know why that happened.  I thought they would fill on subsequent coats, but they didn't.  

Probably not a big deal, but I wanted a smooth surface in these areas that would be inaccessible once assembled.

I sanded the shine off to make the spots more visible, mixed up some epoxy/microballoon fairing mix, and filled in the little holes.  Hopefully the filler will adhere OK and will give a smooth appearance when I add the next coat.

Tonight I also finished up the fairing work on the centerboard and rudder pieces.  I used a homemade longboard as well as the random orbit sander.  These pieces are now ready to be covered with fiberglass after the halves are glued together.

And to get another step closer to that, I glued the weights in the centerboard.