Side Panels Cut and Scarfing Plan

 With this plan I cut both sides and both sheer-strakes from 5 sheets of plywood.

cut plan

 

sheet 5 cut plan

My cut plan aligns the pieces slightly different.  If lofted directly from the plans the pieces fit, but allow little room if I decide to raise the top of the sheer line of the sheer strake.  By rotating the side a few degrees and rotating the sheer strake 180, I gain a wide space in between the two.  I've drawn the possible rise of the sheer strake top with extra lines in the bottom drawing..

 

Sanding my scarf joint

One of the purposes of a scarf joint is to maintain the plywood's thickness.  When sanding down the first of my scarf joints I came up with an idea for a "leveling" sanding block.

 A found a good flat piece of red oak scrap in my shop and checked it's flatness with a metal straight edge.  I then affixed sand paper to the center of it, using a 6 inch peel-n-stick sand paper intended for a random orbital sander.  I don't know why I had this laying around my shop as I don't own a 6 inch random orbital sander (mine's a 5 inch model).  Using a digital caliper I measured the thickness of the board and sand-paper together and then added layers of tape at both ends of the board to achieve the same thickness (approximately).  In my case I used three layers of an aluminum metal duct tape.

 On the scarf joint not only did the epoxy need sanding, but the thin edge of the scarf was pushed up or curled up a little in places.  I used the random orbital sander to take down the bulk of the high areas and then used the sanding block to finish.

Using a regular sanding block to level a surface would require periodically stopping to check progress using a straight edge.  This new block checks the flatness during the sanding with not one, but two methods.  First when the block is over a high spot, the ends of the block will see-saw up and down.  The smaller the amount of see-sawing the closer you are to being flat.  Second, when actively sanding you can feel the bite of the sand-paper.  When the high spot is sanded away, the sand-paper no longer bites and the block slides more easily with less friction (being then supported mainly by the tape on the ends).

Now you might say a really long sanding block will also flatten a surface.  But I think that the ends of such a sanding block can't help but sand areas other than the high spots.  This block only has sand-paper in the middle of it to concentrate the sanding on the high spot while 'leveling' to a much longer area.

 

 

The second Scarf Joint and The Process explained

I had two worries when it came to gluing up a scarf joint.  One was to keep the alignment of the two pieces of plywood parallel (within reason) and the second was to prevent one taper from 'climbing up' the other taper by being pushed too far (making the joint thicker than the plywood).  The "stepped-scarf" method would have easily dealt with both these issues, but the tapered scarf has both these possibilities.  

After some consideration I came up with this process.  The first piece is turned taper down and secured tightly to the table with screws.  This makes it such that pushing the second piece against it, the tapers cannot climb up (not without tearing the screws securing the first piece out of the table) and the two pieces align parallel simply by being pushed together until they can go no further.

During gluing up the second scarf (another 8-footer) I took some photos to document this alignment and gluing process.

Step one was to cover the area of the table with plastic.  I was concerned that when I push the scarf together that I may push the plastic also and have a fold of plastic pushed into the scarf joint.  To prevent this I taped the full edge of the plastic to the table top. 

Step two: With the two pieces scarf-taper up, I wet out the wood with straight epoxy.  The board in the picture acts like a paint roller tray.  I spoon some epoxy out of the mixing bowl onto the tray, wet the roller up well, and then roll it out on the tapers.

The wet-out is completed.

Step Three: The smaller top-piece of plywood is then flipped over, taper down, and screwed down to the table with the clamping blocks.  The clamp blocks have plastic tape on the bottom to prevent being permanently glued down.  The blocks are about 16 inches apart, and in fact use the same screw holes from when the scarf was cut.  The screw in question is the one about in the middle of the blocks.  It looks far from the edge, but is just beyond the taper edge underneath.  The blocks are extra long on the right side to provided leverage to hold the outer edge of the taper down better during the process.

Here is the thickened epoxy glue and the tools I'll use.

Step Four:  Gluing up the taper.  Using the putty-knife I put some beads of glue across the taper and then spread them with the notched trowel.  Okay... I didn't get enough down and not close enough together.

That's better!

Completed

 Step Five:  Before pushing the joint together, I first pulled the plywood back to clean the excess off the plastic.  Don't want a smear underneath.

Step Six:  I push the plywood to within an inch of closing up the joint.  Then I set up two ratchet straps to help with the final squeeze.

Step Seven:  Working the ratchet straps carefully, I close the joint up until I get the joint edges looking to be a proper distance.  I had previously dry fit the joint and knew what the distance should be without a glue layer.  I also knew from the taper angle that a 1mm glue layer would mean the distance would be 6mm wider than a dry fit.  I was also rewarded with seeing a nice amount of glue squeezed out of the joint.  Little to no glue squeezed out of yesterday's scarf joint.  I made the glue less thick than yesterdays and put more of it on the joint today.

 Step Eight:  I screw down the further end of the clamping blocks and remove the ratchet straps.  I also scraped away the excess glue so I will have less to sand down later. 

 

 

Gluing the first Scarf joint

 I completed gluing up the first two 8-foot long scarf joints this week.  The first on Wednesday and the second on Thursday.

On Wednesday the first seemed to go okay, far from perfect, but maybe good enough or adequate.  I think I may have forced the tapers too far together, but I kept hoping some epoxy would squish out the top to show that I had the joint fully filled with glue and closed up well enough.  There was little to no epoxy squished out.

 On Thursday, I removed the clamps and cleaned up and sanded the joint flat.  I don't have x-ray eyes so I can't be certain about the results, but I got the feeling that it actually turned out better than I had thought the previous day.  I think this first scarf joint is not only 'good-enough' or adequate, but probably 'good'.

 

table side of the scarf, after cleaning and sanding.

top side results after cleaning and sanding.

top side end  

 The last picture looks wide, but that was because the taper was cut to such a thinness that it broke away.

Basic Hull pieces / The sheer strake

 Here's my computer drawing.  Many of the pieces are not drawn exactly, but it lets me view it in three dimensions to see what changes might look like.

 Here's the basic hull pieces.  The frames, sides, and first bottom panel.  These are the pieces that will be 'stitched' together when the hull first gets assembled.

 This is a simplified drawing of the basic hull pieces.  The frames in brown.  The two bottom panel layers in blue, and the sides in yellow.  There is also the 'sheer strake' in green.

The sheer strake goes along the top of the sides and visually is what gives the boat's profile view its graceful look.  In this construction it also makes the top 6 inches of the side panels a double thickness.

 

Bottom Panels Cut and Scarfing Plan

To minimize the number of sheets of plywood I'm using, I will scarf my sheets together as shown here.  Yielding both bottom layers from 5 sheets.

Two bottom panels.

Cut plan for sheet 5

The fore and aft scarf joints will be placed one to port and the other to starboard.  The side to side (beam to beam) scarf joints will be on top of each other, but I will mitigate that situation by preventing the scarfs from being contiguous.  If a scarf fails and begins to crack, that crack should not continue into the scarf of the other layer.  My current cut plan allows for at least the 'good' alignment.  Whether I'll be able to shift one layer's cut an inch or two to achieve the 'best' alignment I'll find out.
 

Aligning scarfs of the bottom two layers.

 

 

Scarf Cutting Completed (for now)

 Last weekend I managed to complete the four 8-foot long scarf cuts.  By the end of this weekend I had completed the eight 4-foot scarf cuts.  This completes all the cutting that can be done at this time.  The last two scarfs to cut are the side-to-side scarfs of the bottom panel layers.  They can't be cut until the panels are first widened by gluing up those four 8-foot long scarfs. 

a 4-foot scarf ready to cut.

 

Router Gauge

 This weekend's scarfing showed me the need for an easier way to adjust the router's bit-depth.  

Using some scrap of red oak planking I made a stout little block.  Good weight for a little block and perfectly flat bottom.

Then I found a really old tape measure that had a millimeters scale on it.  Carefully cut it and taped it to the block using some two-sided carpet tape.  I covered the rest of the carpet tape over with duct tape.

gauge block

21.2 mm

Scarfing Begins

In the 'stitch and glue' method of building the hull, the bottom and sides must be single pieces.  On a 18'-6" boat this means the bottom and sides are far larger than a standard 4x8 foot sheet of plywood.  Scarfing is the technique of joining sheets of plywood together to make really big pieces of plywood.

After a couple of weeks of testing both 'stepped scarfing' and the traditional 'tapered scarfing', I chose traditional tapering.  It has two advantages; setting router bit height is easier than the stepped scarfing method, and the flat taper is far easier to spread epoxy glue on.

There are numerous ways of cutting the taper.  Since I already owned a good router I chose this method and made a jig to router the taper at a consistent angle.  Searching the internet shows many jigs for router scarfing but most are for narrow boards.  I need to scarf the entire 8 foot length of my plywood and pondered some days away to design this carriage sliding along a groove in a straight edge.

 This jig is specific to 12mm plywood, cut to a 3 inch wide taper.  The angle the router runs up and down at is determined by the height of the carriage runners.  The bottom runner slides directly on the table and the upper runner slides in a channel on the straight edge.  

I did a test on some scrape plywood in my basement shop. This gave me an important piece of knowledge.  With this jig setup and method it is very important that the table, plywood, and straight-edge guide be at precise heights.  I accomplished this by screwing the two sheets of plywood to the table every 16 inches and screwing down the guide every 8 inches, holding the whole works tightly together.  Yes, this puts many screw holes in my boat, but putty and paint cures many things.

Side notes; Carriage and straight-edge guide are made from an old piece of pergo flooring.  To prevent the carriage from bending to the weight of the router I nailed and glued two short walls on either side just under the router handles.  Also, I placed the bottom stop precisely to prevent the router from cutting into the table, which in my case is other pieces of plywood stacked up.

Cutting is done in three stages.  The first two takes off about 5mm each stage, then the third time the router bit-depth is carefully adjusted to do the final cut.  Even with the vacuum attached to the router, I had to stop a half dozen times to vacuum away the piles of sawdust.

The first 4 feet cut.  The guide is then moved to the remaining 4 feet.  The plywood remains screwed in place. 

First 4 feet of the 8 foot length.

 The finished cut, unscrewed from the table and separated.

The finished cut.

 There are 12 scarf joints to be done before the bottom and side panels can be cut out.  There are four 8-foot scarfs, and eight 4-foot scarfs.  A total of 64 feet of scarfing to do.  I managed to get two 8-foot scarfs cut on Saturday and two more on Sunday, that's 4 of 12 scarfs and half the total distance.  

Today I rest.

 

Progress again. Second coat of Epoxy.

 April was a busy time at work but I'm now into my part-time phase of retiring so I've managed to find a little time to continue on the boat.

I've managed to get two coats of epoxy on the frames and bulkheads.  I feel this is enough to seal the wood, which is the primary goal at this point.  After the hull is assembled the plywood will receive several coats of either paint or varnish (varnished 'bright-work' will be mostly inside the cabin only). 

all shiny now.

 The first coat of epoxy was to 'wet' the plywood and so was spread fairly thin using a plastic squeegee and then rolled with a foam roller.  Like any first-coat, this raised the fibers of the wood and received some sanding before the second coat.

I wanted the second coat to have some thickness and I sought a way of distributing an even amount of epoxy across the plywood.  At first I tried a notched trowel, but found the thin and runny (low viscosity) epoxy just flowed through without really spreading.  Then I tried my plastic squeegee but couldn't regulate all the areas to have roughly the same amount of epoxy.  

4-1/2 inch mixing bowl, 3/4 inch wide mixing stick, and 4 inch foam roller 

 I ended up with a technique of making a batch of epoxy (estimating how much to make up).  Then I used my mixing stick to spoon it out of the bowl and drizzle it around the entire piece until the bowl was empty and the drizzled epoxy looked roughly distributed evenly.  (Oh, the binder clip on the mixing cup??  That's a reminder to always pick it up from the same side, so I don't get the epoxy all over my clean gloves.)

Next step was to roll the drizzles flat to spread them out.  If my roller was new, I made one area of drizzles extra thick and started my roller there so that the amount of epoxy used to wet out the roller did not leave the starting area too thin.  Roll with long strokes and keep away from the edges at this point, you don't want a thick drizzle splotch pushed over the edge.  (I can't recommend having palsy in your old-age, but the shaky hands do, in fact, make drizzling back and forth effortless.)

After the initial roll out, I worked the edges.  Using shorter strokes and the roller at an angle to the edge.  The angle allows me to roll most of roller past the edge without actually dropping over or off the edge. 

After all the edges are coated, I finished by rolling the entire area first one direction then the other.  This gave what at least appeared to be a fairly even and uniform thickness of epoxy across the whole works.

Using a slow version of epoxy hardener, allowed the epoxy to still be fairly wet after the rolling.  This allowed time for the low-viscosity epoxy to spread and level itself resulting in a somewhat smooth surface without roller marks or impressions.

I did not do the 'tipping' the books talk about.  Tipping is following the roller work with a gentle one direction brushing to help smooth things, pop air bubbles, etc.  

 

update... still here

 I've been busy with work stuff, so the progress on the boat is at a stand-still for a while.

I did manage to get down to the club saturday morning.  It was nice to hang out for a while that was not work or home.  One of the members brought his mostly finished boat in and gave a talk and answered questions.  Afterwards another member and I assisted him in launching it for a trial.  He was testing the seating position.

It's propelled by a curious foot pedal mechanism.  The pedals don't go round like a bicycle, but push back and forth.  This causes the two blades on the bottom to flap side to side.  When moving each direction they tilt at a slight angle which translates to forward motion.

 

Epoxy Coating

 When I was repairing the old rowboat I bought a gallon of System Three epoxy, but since then I've done a lot more reading on epoxy.  One of the drawbacks of epoxy is that when it fully cures a by-product called 'amine blush' rises to the surface.  This must be removed before you can do another layer of epoxy.  Although amine-blush is a wax like substance, it is water soluble and is fairly easy to clean off.

But with further searching I found the MAS brand of epoxy whose formula prevents any significant amine-blush, so it does not require washing between coats.  It still recommends sanding between coats like System Three, but there's no messy washing and drying every little part.

I will use up the System Three doing the gluing of layers together and for filleting in the corners, but for all the surface coating and for the fiber-glassing I will be using the MAS brand. 

 I managed to get a couple of hours epoxy work done this last weekend, and succeeded in getting one side of all seven pieces coated.  I did the three larger pieces on Saturday and finished the others on Sunday.  Each session lasting about an hour.  During this hour, I mixed 3 to 4 batches of epoxy, so it was always fresh, but the foam roller began to gel and stiffen up by the end of the hour.

 My technique consisted of drizzling a line of epoxy at one end, scraping it out with a squeegee to cover as much area as I could, and then rolling over it with the foam roller to even it all out.  I was using moderate pressure with the squeegee so this may be a thinner layer than other people do.  All my reading has not turned up any specification for layer thickness (some recommendation saying how many grams of epoxy covers what area would be nice??).  This one coat of one side of these 7 pieces used about 11 ounces so far, out of the 1-1/2 gallon (192 ounces) jugs.

Whether I will do two coats or three coats at this point, I don't know.  This is a pre-assembly stage and there's plenty of opportunity later for more coats. 

All Frames Cut

 All the frames have been cut.  With the exception of the tops of 2, 4, and 6 which form the cabin top and motor well cover whose heights are yet to be determined.  In this picture I drew where 2 and 4 might be cut.

The next step is to paint them thoroughly with epoxy to seal the wood.  Two or three coats of epoxy will be required.  I've arranged them around the various tables of my basement so that I'll be able to paint all seven at once.  At least one side of all seven.

I'm concerned with how much garbage that working with epoxy generates.  If I use a brush or roller there is no cleaning it and it simply becomes trash.  My mixing bowls are paper soup bowls and wood stirring sticks, but those too become garbage.  Thus I will attempt to paint all seven in a single go.

Online Outboards

 Purchasing online from a company and website you've never dealt with before can be a risk.

Even after googling and searching forums for reviews still left a small chance it would be a total scam.  The feelings are only reinforced by the very good prices compared to known stores.

So if you're out there wondering about Online Outboards, I will add my review for what it's worth to you.

This place was excellent!  

The online purchase was easy and seemed secure.  The price on the motor's webpage was exactly what I paid, no hidden fees and free shipping.  All the confirmation and receipt emails were prompt and looked good.  The shipping included a tracking number within a couple of days of purchase.  It arrived across country in about a week.  The shipping was free and included having FedEx deliver using a 'lift-gate' truck.  The outboard's large box came on a special size pallet.  The outboard is spec'd at 118 lbs, but the whole package and pallet was listed as 190 lbs on FedEx.  But no worries, the driver used his pallet jack to move it from his truck right into my garage.

(This website is NOT monetized and I received nothing from Online-Outboards for this review.) 

Outboard Purchase

An early stage in assembling the hull in a Redwing is building the motor well.  To make this right, it needs to be designed to fit the motor that will be installed.  To get the measurements right I really need the motor in-hand to really figure this out.  Thus the motor is being purchased long before the hull is complete or the boat hits the water. 

The first thoughts were to get a Honda 8 h.p.  This boat is intended to be a slow cruiser and 8 to 10 hp should do it well.  Honda has a stellar reputation for reliability and quietness.

Further research found that the Honda 8hp and the Honda 9.9hp are in fact the exact same motor.  The Honda 8hp is just a throttled down version.  So I thought I would get a Honda 9.9hp.

The Redwing-18 is best fitted with a 'short' shaft outboard.  Also, the Redwing uses a ship's wheel not an outboard's tiller handle, so setting it up for remote control is needed.  Honda makes the short shaft versions, but does not offer a remote controlled version in the short shaft length, only on the long and extra long versions. This would mean that a few essential modifications to the Honda would be needed for remote control and some of these parts (Honda OEM parts) are not particularly cheap.

I had my eye on a Honda 9.9hp at OnlineOutboards.com, but before I could pull the trigger they went out-of-stock. After some weeks of waiting for Honda to be back in stock, I went to the local Boat Show.  Not a Honda in sight!  Nearly all the displays were Suzuki or Tohatsu.  

Browsing Online-Outboards, I found not only plenty of Suzuki but lots of Suzuki models in remote versions complete with the Suzuki throttle included.  In addition, the Suzuki 9.9hp remote version was on sale as an overstock item, $2,710.  This one is also their electric start and power-tilt version.  Just what an old man needs.  The motor comes standard with a 3-gallon fuel tank and the fuel line.  The included throttle handle came with the wiring harness that is plenty long enough for the Redwing.

The Honda 8hp and 9.9hp are the same engine (same 222cc displacement, bore & stroke).  It turns out the Suzuki line does the same strategy of sharing the same motor for different HP sizes.  In the case of Suzuki, the 9.9hp is the same engine as the 15hp and the 20hp (same 327cc displacement, bore & stroke).  So whereas the Honda 9.9 would be the maximum h.p. for that engine, the Suzuki 9.9hp is the 20hp throttled and restricted down to be 9.9hp.  A 20hp engine working along nice and easy as a 9.9hp version.
 

Signs...

 How can an employer tell if an employee is considering retirement??

There's an outboard motor under his desk!

 

The Frames explained.

 It dawns on me that I haven't shown a decent picture of what the frames are and where.

1: frame-1 is at the foot of the berths.  My feet will stick through this when sleeping.

2: frame-2 forms the front of the cabin area and so its upper portion is also a 'bulkhead' between the cabin and the fore-deck area.

3: frame-3 meets only the bottom and sides the hull.  

4: bulkhead-4 is the largest and is the bulkhead between the outside cockpit and the inside cabin.  It will contain a door.  The roof of the cabin also has a sliding hatch.

5: frame-5 is the middle of the cockpit area.

6: bulkhead-6 is the front of the enclosed stern area which includes the motor well, and encloses the outboard motor.

7: although the Transom is the back of the boat and is double thick plywood, in this case it does not support an outboard motor.  The outboard is mounted on the front of the motor well structure. 

 

So far I have completed the Transom, frame-4, and frame-1.  The others have been drawn on the plywood and rough cut around them with a jigsaw.  Getting all the frames done and coated with epoxy is the goal for the winter and can be done inside a warm basement workshop (I'm still working full-time during this period).

 

Progress on Frames (Frame-1 completed)

 I've been delayed a little with work and minor health issues.  A bad back had me spending most of the weekend in bed.

I did manage to get the #1 frame completed.  It was one of three frames that were cut in 2 pieces and had to be scarfed back together.  This is not the plywood scarfing that boat builders usually talk about where the plywood is cut at a taper and joined so to keep the plywood the same thickness as if its one long piece.  This is what I'm calling a 'construction' scarf.  In home building if you're joining two boards in length you add another board along side it.  That added board is known as a scarf.

Here's the completed frame-1 (soda can for size perspective.)  You can clearly see the glue joint down the center. 

 Here's the back side, showing the two scarf boards.  Frame-1 supports the fore-deck which may have two people standing on it, so I chose to do the scarf the full width to make the top of frame-1 a more solid beam.

 This is the butt-joint of the two pieces with the scarf board over it.

The bottom, top, and sides were cut at angles to align to the hull and deck.  These are just approximate angles.  It all gets embedded in epoxy glue and fillets, so precise match of angles is not necessary.

Just for fun, I added a fillet and sanded round the ends of the scarf boards.

Frame-1 is the foot-end of the sleeping bunks.  I used a router to round over the sides and top of the inside of the frame so that bashing your toes is a little less painful.