Thursday, October 30, 2014

Shaping skegs using router and template

With the skegs rough cut and laminated, the next step was to bring them down to final dimension.  Keeping the curves fair and the right shape to fit the hull, and keeping both skegs identical was a daunting prospect.  

However, I realized that I could use the pattern I cut to trace out the parts as a router template to trim the skegs to final shape.  The first step was to screw the pattern to the rough-shaped part.

I then used a pattern bit with a bottom bearing in the router table to trim the stock to the final dimension.  As you can see, the bit is not long enough to to the entire side, and there is also a little lip on the bottom between the bearing and the bit.  This won't be a problem.

Here's a shot of the nice curve towards the stern. 

Once I went all the way around, I removed the template, and switched to a pattern bit with a top bearing. The bearing now bears against the part of the skeg that's already routed to final dimension, and brings the remainder of the edge into line.  I flipped the stock over to get both edges finished.

The masonite I used for a pattern was a little bit too short, so I now drew in the curve at the stern and cut that out with a jigsaw.

And shaped it to final dimension with my Shinto rasp. 

Looking good.  The fit to the hull is as good as you make the pattern.  In my case, I'll have to do just a bit of minor fitting before I'm satisfied.

Next I routed the finger grips in the sides of the skegs with a bit that looks like this.  This is 3/8" radius, and I cut about 1/4" deep.

The grooves look like this.  The gentle curve of the skeg was easy to run against the fence for consistent spacing.

I followed up with a 1/4" roundover bit on the edges so that my fiberglass cloth will lay over there nicely, and hand sanded the edges of the finger grooves to get rid of the sharp edge.

Next I put tape over the bottom of the holes where there were voids in the plywood, and poured in unthickened epoxy to fill those spaces.  

After that cures I will do a little fairing work to fill the slight depressions that are left, some edges that chipped out a bit, and any other irregularities.  Then I will fiberglass these parts.

Sunday, October 26, 2014

Skegs under construction

Pretty much the last bits of boat to build and install are the two skegs on the bottom of the hull. These provide a stable base for the boat while on the trailer or beach and also are handy handholds to right the boat if capsized.

I looked through my bits of wood laying around and didn't find any solid stock that was inspiring, so I decided to build these from standard ACX plywood.  Two thicknesses of 3/4" ply is the right thickness, and as these will be completely fiberglassed  I think they will hold up just fine. And if not, I can always replace them with something else.

Working with the sheet plywood means that I won't have to splice parts together, and it should be easier to build parts that are straight.  Any voids I find I plan to fill with epoxy.

The first step in the process was a trip to the local newspaper, where I bought an end-roll of newsprint.  I unrolled a length and layed out the pattern for the skeg based on dimensions in the plan addendum.

I then perforated the pattern with an ice pick and mallet to transfer the curves to a piece of masonite, which I then cut out with a jigsaw.

I faired the curves with block plane and sandpaper and the result is shown here on the hull:

With the pattern made, I could trace out the four pieces I needed to cut.  Another alternative would have been to cut out and finish one piece, and then trace from that.

I used a jigsaw to cut the four pieces to rough shape,

And laminated the two pairs.

I was careful to ensure the glueup was straight.  In the foreground you can see a tall bar clamp applying a bit of down pressure, in the middle a stack of plywood cutoffs supports the center, and in the background the tips are under a ladder step to bend them down a touch.  I used a 4-foot level as a 'straight' reference before all the clamps were in the way.

Here are the rough glued up parts in approximate location on the hull.  I'll next bring the edges down to final dimension, fill a couple voids in the ply with epoxy, rout finger grips in the sides, and round over the edges that are not in contact with the hull. 

I'm thinking I will fiberglass these off the boat, since it will be easier to work on them.  When they are finished I'd then install them with epoxy and fillet them generously to the hull.  I'm thinking right now that I do not need to apply fiberglass tape to those fillets, and that will save time finishing that area.

Hull fairing and final epoxy coat

Upon my return from Sail Oklahoma, I continued work on the hull bottom.  In places where the fiberglass overlapped I needed to apply fairing compound and sand it back to make the transition gradual.

At the bow, the cloth on the garboard planks overlaps the bow transom, and the cloth on the tramsom overlaps the other way, and onto planks 2 and 3, which have no cloth.

The seam in the cloth falls across the garboard plank in front of the centerboard slot,

And at the stern transom cloth laps both ways, plus an extra thickness where the seam between the two pieces of cloth on the bottom meet.

The fairing mixture I used was epoxy thickened with micro-balloons (tiny glass spheres that sand easily.  I applied it to all the places shown above and sanded it back.  There were still a couple low spots (more easily detected with the hand than the eye), so I applied more to those areas and sanded again.  

I eventually got to a point where I decided it was good enough', and then applied a final coat of epoxy.  I did that because I felt there were some tiny spots in the weave of the glass cloth that were not fully filled, and on planks 2 and 3 there were a couple areas where I had accidentally sanded down to or close to bare wood.

The real test of how well I did on the fairing will be when the paint is on and the boat is out in the sun catching reflections from everything around.  But the shiny fresh epoxy gives a preview and confirms that it's good enough for me.

Sail Oklahoma report

A couple weeks ago my build progress got interrupted for a week as I traveled with my wife to the Sail Oklahoma 2014 small boat gathering.  We had a great time meeting new people and looking at a wide variety of home-built boats - everything from skin-on-frame paddle craft to large multihull boats.  

There were classes on various subjects and talks by boat designers from across the globe - U.S., Canada, Britain, Australia and New Zealand.  And the weather was poor enough at times with the remains of a hurricane wetting down the site that cramming into shelter and listening was a perfect use of the time.

I was particularly pleased to meet and talk with John Welsford, the designer of the SCAMP sailboat.  Here's John teaching one of his classes - this one was on sharpening tools.

There were three SCAMPs there on the water, and the Monies' Red Scamp, which was on display in the yard. 

Here's Paul Breeding's "Forever Young", attending from Colorado.  This is the SCAMP that got me inspired to build my boat when I saw it at the Lake Pepin Messabout 18 months ago, and Paul was nice enough to take me out in her:

Here's Phil McGowan's Scamp, down from Idado, which I was also able to sail in:

And from Florida, here's Kenjamin's experimental take on the design, with his wishbone mast in evidence. 

There were also other Welsford designs attending - here's a Tread Lightly from Kansas:

And a real nice Houdini from Tennessee:

A Navigator from the local area, 

And a John Fisher's Sweet Pea, also from Colorado.  We had a nice sail on her.  She's a much bigger boat than the Scamp, and has been on the TX200:

Probably the single design with the best representation were the Puddle Duck racers.  PDRs are boxy 4 foot wide 8 foot long sailboats.  The hull form is specified, but above that anything goes.  Here's a cool artistic take on the design - the Chevy Duck, with working lights:

Those duckers have a lot of fun - here's a shot of them out on the course rounding the first buoy in their class race.  Of course the buoy is - an inflatable duck!

These are simple boats that are a lot of fun - I may have to put one of these together after my Scamp is done...

Thursday, October 2, 2014

Fiberglassing the hull

With the hull bottom filled, sanded, and edges rounded over I could proceed to apply fiberglass.  I purchased 50" wide fiberglass, which I believe is the widest that is generally available.  Even so, this width is not wide enough to cover the hull bottom and both garboard panels, so a seam is needed.

I determined that I could lay the cloth on the hull so the seam would run through the middle of the centerboard slot, reducing the amount of overlap that needs to be faired and smoothed over.  I covered the remainder of the hull with a leftover piece of a narrower width left over from a previous kayak project.

After trimming the edges I started saturating the fiberglass.  Rather than using a squeegee this time, I used a roller to apply the epoxy.  This worked well, was very controllable, but was somewhat slow.

Job done.  Here you can see the overlap seam aft of the centerboard slot.  As it turns out, this will be near the skeg that is installed later, so any unevenness in the seam will be fairly unobtrusive.  Another reason to run the seam here vs. down the center of the hull bottom.

Here's where I ran the seam in front of the centerboard, minimizing the amound of fairing I will need to do.

I also applied cloth to the bow and stern transoms, and overlapped that onto the hull panels. This was a little fussy, as I had to cut away around the hull strake laps.

And here's a shot with the first coat of thickened epoxy on the cloth, and the 2nd coat of epoxy on hull panels 2 and 3.

After I finish filling the weave of the fiberglass, the skegs get installed, and then paint.

Rolling the hull and prepping for fiberglass

Now came a moment I'd been anticipating for a long time - rolling over the hull.  To prep for this I got 4 hefty eye bolts and screwed them into the ceiling joists.  After removing the four screws holding the boat to the jig, I looped my big cargo straps under the hull, ratcheted it up, and removed the building jig.

I resisted the urge to climb in and sway around and pretend I was at sea...

I was able to roll the boat pretty easily, while my wife watched that the front strap didn't slip off the bow.  The hull didn't really spin freely in the straps - I had to lift and slide.

When it was completely upside down I placed a couple sawhorses under the seats after measuring to ensure they were tall enough to keep the cabin roof off the floor.

These straps quick release rather than gradually lowering, so we worked this by me supporting the boat, my wife releasing the strap, then I would lower the boat a bit and she would tighten the strap again to support it.  It took a couple iterations, switching from one end of the boat to the other, and then we were securely on the saw horses. About a half hour process overall.

With the hull upside down I could clean up around the ballast tank drain.

And trim off the ends of the centerboard case. 

And fillet the hull panels and fill in the garboard/hull bottom joint with thickend epoxy.

After that cured I gave that joint a generous round-over,

And also rounded over the hull panels where they join the bow and stern transoms. 

And routed a round-over around the centerboard case opening.

I finished up by sanding the hull in the areas that will have fiberglass applied, to remove any rough spots.  

I feel good about getting past this step of the process!

Rubrails installed

Rubrails are just about the last structural item to install.  

But before doing that, I put on this trim piece on the bow.  The plans call for the bow transom to be completely flat, but when I installed the deck I noted that I had a bit of extra length, and so left it in place.  I now cut this piece to finish off the bow.  No steam bending or anything here, it's just cut to shape.  It has beveled edges top and bottom and fits in nicely.  There will be a shadow under this and I think it will look better than a completely flat front.

For rubrails I elected to use some clear fir I had on hand in 14' lengths, old floorboards. They were pretty dirty to I cleaned most of that off with a sander, then ran them through the surface planer, and cut them to width with a circular saw.  The sheer curves horizontally, vertically, and twists, so I had to soften these up with the steamer.  It took a lot of steaming, and even then this wood didn't bend too well, but it was enough.  

I clamped them in place below the gunwale to hold their shape.

And after they cooled down removed the plastic back and reclamped them to dry.

Then installed them with epoxy and used screws to clamp them.

All trimming and rounding of edges will be done with them installed on the boat.