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.

Hatches and Secret Passageways

Starting with the stack of hatch opening reinforcements and hatch stiffeners from my last post, I have laminated, cleaned up glue squeeze-out, trimmed, rounded corners and edges, and sanded until I've had about enough of that for a while!  But now they are all ready to go.

Here's a pile of laminated hatch stiffeners on the left and the port seat hatch reinforcement on the right.

Here are the cockpit sole hatch opening reinforcements ready to install.

And here they are clamped up waiting for epoxy to cure.  I made these PVC pipe clamps about 15 years ago when I built my first kayak.  The idea is from Chesapeake Light Craft, and they are made from 4" schedule 40 PVC, cut about 1 1/4" wide, and then cut so they can spread open.  They work well, and are cheap to make.  I find they are best clamping about 1" thickness, they are a bit less effective on this thinner glue-up, so I used a bunch of them.

First coat of sealing epoxy is on those now.  I'll sand the fuzz off and put a couple more coats on before this gets installed.  Same progress with the hatches in both seat tops.

I've also started gluing on the hatch stiffeners to the back side of the hatch lids.  As with the hatches I did for B3, there is some twist in the plywood, so I twist it a bit the other way (see the 4 mm spacer at lower right) and glue it up.  I try to guess right with the spacer so that when unclamped it springs back until it's flat.

As I was doing all this hatch work I was thinking about drainage.  I was thinking that the cracks around the hatches in the cockpit sole are likely to get filled with water in the normal course of events from wet swimsuits climbing in, rain, overflow from filling the ballast tank, etc., and that water would fill the cracks and stay there until it drains into the storage areas if the hatch gets opened.  It seemed to me that could be irritating.

I have seen others rout a channel the full depth of the sole doubler (the top layer) to allow that water to drain away.  But I didn't like the look of that.  After a bit I came up with my idea of "Secret Passageway" drainage!  

I routed a drainage channel on the underside of the sole doubler leading from one corner of the hatch opening to the gutter that runs down to the sump in the rear of the boat.  I cut the channel about half the thickness of the plywood, and angled it back at a 55 degree angle.  The sole has a slight tilt towards the rear so water should drain through here by gravity.

The openings are pretty much invisible, and the cockpit floor is undisturbed.

If these would ever get plugged with gunk it should be pretty easy to poke something through there from the hatch opening side to clean them out.

These channels will be well coated with several coats of epoxy to prevent water from seeping into the plywood, and I'm making a special tool (ok, basically a rounded stick) to run through the channels as I glue the two pieces together, to clean out any thickened epoxy that squeezes into the channel and would block it. 

I think this is going to work nicely.  Any other SCAMP builders that want to borrow the idea please feel free!

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July 27, 2014 addendum - I had a question in the comments about the router and templates I'm using for some of the build sequence, so heres' a shot of the Porter-Cable router.  I've had this for probably 20 years - I don't know if they still make this model (#693 with a #6931 plunge base)

Here's a photo of the bottom with a template guide bushing installed, and some of the other spacers that I've used on this project: 

And here's a shot from above showing the knurled ring that fixes the template guide in place.

Cutting cockpit sole and seat top hatch openings

With the hull panels now installed, I put a coat of paint on the inside, and will show a photo of that when I've got the final coat done.  I took a little break from painting and turned my attention to constructing the remaining hatches in the cockpit sole and the seat tops.

I used the same technique I described earlier in > this blog post <.  I used all the same template guide bushings and reused the template itself for three of the cockpit sole hatches and for the hatch on the port seat.  I needed to make additional templates for the ballast tank opening, the starboard seat top hatch, which is narrower due to the centerboard trunk, and the round openings for the plastic hatches in the back corners of the seats.

I took a while to finalize the locations of the cockpit sole hatches, measured (several times!), and started making sawdust. 

Here are the holes completed in the top layer.   These were cut out with a 1/8" bit, and I plan to use the sections cut out as the hatch covers.

In the bottom layer I cut the holes smaller, and included a groove for the gasket.

And then I spent a few hours cutting all the additional backing plates and hatch stiffeners from 1/4" birch ply.  Lots of changing template guides, collets and bits was involved.

Next up, I will sand off the fuzz and round edges and corners, laminate two layers where appropriate, and install them.

B3 hatch openings cut and backing plates installed

After completing the installation of bulkheads 4 through 7, the next order of business is to install B1 - B3.   However, I wanted to install access hatches in B3, and decided I should do that before installing the bulkhead, as it's much easier to work on now.

I needed to cut out the hatches, manufacture a backing plate for the hatch to seal against, and make hatch stiffeners to reinforce the hatch itself.  I decided to make a router template to make all the cuts.

First I did some paperwork to figure out the template spacer diameters I would need.  I used a 1/8" bit to cut out the hatch, a 1/4" diameter bit to cut the groove for the gasket, and a 1/2" bit to cut the inner rim of the backing plate.

With dimensions in hand I moved to the lathe to cut out the spacers.  I used a template guide with no spacer for the first cut, so just needed to create two.  I used 1/4 aluminum.  In the photo above you can see dimples on the spacer where I hit it with a ball pein hammer to snug up the inner diameter.

I then drew out the template.  The opening size I decided on was 12" x 18", and I needed a line outside that to account for the first template guide.  I then cut out the template with a jig saw, and smoothed it with spokeshave and drum sander.

Then clamped the template to B3, took a deep breath, and cut out the hatches.

As I was cutting out the backing plates, I realized I could also cut the hatch stiffeners from the same piece of ply, using the same template, by making a big spacer (about 6" diameter).  I cut that spacer out of plywood, and it worked fine.

 After cutting out the backing plates, I checked for fit.  Looks about right.

Next I laminated the hatch stiffeners.  I am using two layers of 1/4" baltic birch plywood.  Nice wood.  I would have bought 1/2" thick if it was available.

And then laminated the backing plates.

After cleaning up the glue squeeze out, rounding over the edges, and an overall sanding, I 

installed the backing plates in the bulkhead and cleaned up the glue squeeze-out.  

I had to clampea board across the bulkhead to keep it from sagging from the weight of the clamps!

Nice to have that job done.  There will be a little followup work on these to coat with epoxy, but I can do that after the bulkhead is in the boat.

I'll be able to use this same technique for the seat-top hatches and the cockpit sole hatches.  I can use the same router bits and template spacers, I'll just need to make a new template for different sized hatches.  Should go a lot quicker next time.

Lead Pour - centerboard and rudder

Thanksgiving Day in the shop - I worked today on adding lead ballast to the centerboard (22 lbs) and the rudder (2 1/2 lbs).  The latest plans addendum was published just in time.

Starting with the centerboard, I used a large calipers to verify the thickness, marking the 13mm contour so the router would not break through at a depth of 10mm.  

I calculated how much space was needed and built a template for the router out of one of the offcuts from the kit.  I fastened the the template on with 1/2" pins driven with my Cadex 23 gauge pin nailer, which worked great.  When done, the template pulled off, leaving the pins, which I pulled with a pliers.  I cut to a depth of 10mm and left an island in the middle so the router wouldn't dive in, and later put a big base on the router and removed the island.

I did the same for the rudder, but cut these only 7.5 mm deep.

I got out my little aluminum foundry and fired it up to melt the lead.

Fun to pour metal...

There must be a bit of moisture in the plywood, as the lead bubbled and boiled.  This was a much bigger issue on the centerboard pours which have a lot more metal in them.  

Due to the bubbling, there are some voids in the underside that I may fill in after I get things smoothed out and check the final weight.

So, I'm happy with this progress today!