Building Frame and Inner Stem

Been a while since the last entry, but I’ve been pressing on.


In the week or so before Labor Day I’d assembled the building frame that will provide a solid platform on which to assemble the boat at a convenient height.  It’s not at all sophisticated, just two long 2×6 beams and a series of cross-members.  Unfortunately, in spite of my best efforts, it ended up with a twist at one end.  So the corner nearest you in the picture is high by a bit less than 1/4″; more than I could take out by shimming it around.  One of the main points of the building frame is to provide a level surface for the temporary forms to sit on, so this is not ideal.  I briefly contemplated starting over, but decided instead to just cut the top surface down as  required in the area where the last mold will get set up.  The molds will need to be checked and fine-tuned anyway one they are set up.

Nevertheless, I needed to level it as best I could, which I did by building a water-level out of some scraps of wood along with a length of tubing and a couple of stainless-steel rulers from Home Depot.  For those unfamiliar, the principle of operation is that the tube is (mostly) filled with water with the ends left open to the air.  The level of the water in each end of the tube will always be at exactly the same height.


This arrangement worked pretty well to get the level close over the length of the frame (save for the aforementioned defect).  The only headache was that I think the inside of the tube on one end became contaminated with something so that the meniscus was considerably deeper at one end than the other, making reading it tricky.  I compensated by factoring in the offset when the two ends were set up next to each other on the same surface and double checked measurements by swapping the two ends.  Hopefully, it’s Good Enough™.

Then it was time to set up the molds set up at their locations; check that they were perfectly (haha, sure) vertical, level, and square to the centerline; and brace them in place.


You may notice that two of the molds still need to be braced.  That is because I decided to spend yesterday FINALLY making a part that will stay on the boat.  First up is the inner stem (described in a previous post) which is laminated (glued out of many strips bent around a form).  I am using Douglas Fir which is fairly strong and not too heavy and takes epoxy well.

I used a circular saw with a home-made ripping fence to cut strips 3/16″ wide.



The form is blocks of wood screwed down around the curve from the pattern I made from the lofting.  This picture Dry_Fitshows the form with the strips temporarily dry-fit to practice getting it clamped up and to confirm that the strips would bend without breaking (in fact one did; fortunately I’d ripped a couple extra).  Once mixed, the epoxy starts to cure in the pot within 20-ish minutes, so taking the time to work through the process once before it was a race against the clock seemed wise.

After laying down some plastic sheeting and taping the form blocks and clamp pads with packing tape (to avoid the form and the clamps becoming part of the boat), and making sure everything needed was handy, I was ready to go.


15 frantic minutes later, including a minute or two of panic when I found I hadn’t mixed enough epoxy to begin with and had to whip up another batch with the strips partially coated, and the die was cast.


There was a bit of sweep in the original board that the strips came out of meaning that the strips don’t lie perfectly flat along their edges.  I flipped every other strip over  so there wasn’t a bias towards one direction in the final part and crossed my fingers that I could tap them down flat (hence the mallet) and that the friction (even slathered with epoxy) would hold them there while it cured.  I’m not sure I got it totally flat, so some trimming may be required.  Hopefully not very much as the width of the strips is already pretty much the minimum required to get the intended final width of the part – a limitation based on the available size of lumber I could get without a lot of resawing and planing which I don’t really have the equipment for.

The acid test will come after a day or so when it’s cured completely and I can pull it off the form.

You’re not supposed to clamp epoxy laminations too tightly for fear of squeezing all of the goo out of the joint.  That’s a good thing because tightening all those small round clamp handles much at all with slippery epoxy-gloves was nearly a lost cause.  I did manage to get it pulled in to the form, but it was a pain.  The quick-grip clamps like this might be a better tool for this job.


Over the weekend I finished up the temporary molds that I started working on in May.  There are seven of these total, and they were quite a bit more time consuming than I had expected (I sense this may become a theme…).


The fore-most and aft-most molds (the first two in the picture) don’t have too much curvature to them, so they are made up of just two pieces plus the cross-member at the top.  These took me around 3 hours each.  The process for each was

  • rough-cut stock for the two halves
  • transfer the curve from the lofting using the nail-heads technique described last time
  • cut and fair the curves
  • trim the mating faces
  • mark the top of the inner-keel, waterline, and sheerline
  • assemble the mold halves and the cross-member
  • mark and cut the “pocket” into which the inner-keel/inner-stem will be located.

The other 5 molds have enough curvature that each half needs to be made up of two boards joined together at an angle so in addition to the above, there is an additional step of joining the two boards together to make up each half of the mold.  These 5 each ended up taking me between 4.5 and 5 hours.

With them all finally complete, I couldn’t resist setting them up roughly in their positions on the floor to get a sense of the shape and scale.


Happily, it passed the sort-of-looks-like-it-could-be-a-boat test.  The shape looks lovely in person, although you don’t quite get the full picture without the fore and aft stem profiles which I couldn’t set up because they extend below the floor-level here.  So that will have to wait until the permanent set up on the building frame.

Then it was tear-down time for the lofting and an hour or so of shop clean-up in preparation for starting on the building frame.

Finally Back At It

I’ve finally picked back up with the boat project after a several month hiatus through the winter and early spring. The lines plan on the lofting is now essentially complete.  There are a few other details I may lay down on the lofting here and there for reference as I find them useful, but for the purposes of the fundamental structure it’s all there.  So I’ve moved on now to pattern- and mold-making.

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Arcs and Arks

On returning from an evening out a week or so ago, Jude stopped in to say hi and snap a couple of pictures while I was hard at work lofting the aft stem profile.  For the benefit of non-boat-types, this boat is a double-ender which comes to a point at both the front and the back.  The pointy ends are the stems.  Stern_BattensAs I bent a batten to the arc of the stem Jude observed that this was a very obvious step seeing as how I am building an ark.  Little did she know that the very line I was drawing for the stem is called the rabbet, and there will even be a pair of rabbets on this ark. Okay, rabbets not rabbits, but who’s quibbling over details.

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On To Lofting

It may seem a bit ironic that this entry comes very nearly two weeks after my Something Every Week entry.  But, in fact, there has been progress in the meantime.  In the last episode, our ambitious (read: novice) boatbuilder completed the lofting floor and readied himself for beginning to lay down the grid and lines.

First up was laying out the grid for the lofted drawing.  Boat shapes are captured in two dimensions on the drawings in the form of lines and coordinates of the hull’s intersection with three sets of planes in space.  These datum planes are the Stations, which are vertical transverse planes (think a sliced loaf of bread); the Waterlines, which are horizontal planes parallel to the (wait for it…) waterline; and Buttocks, which are vertical planes aligned parallel to the longitudinal centerline.

DrawingStationLines_smallerSo to begin the lofting, lines representing these various planes intersected with the lofting floor are laid down.  These will form the grid on which the various intersection lines of the hull shape are projected in profile, plan, and body (i.e. end-on) views.  Here, I’m using an improvised beam compass and some high school geometry to mark the station lines perpendicular the base line.

Next up was to get some battens together to use for drawing and fairing the curved lines representing the boat shape.  These need to principally be straight, uniform, and have appropriate stiffness to be able to be bent into fair curves.  I was able to find a few pieces of lattice at the local lumberyard of suitable dimensions for some of the shorter, tightly-curved lines, but for the longer, gentler curves like the sheer profile and such I needed to make something up.

Making this long batten proved to be more of a hassle than I anticipated.  I found a 14′ length of 3/4″x4″ clear, vertical grain cedar molding which looked promising to rip a couple of strips from to be glued together for a nice, almost 28′ batten.  This is essentially what I did, but the only fence I was able to find for my circular saw really wasn’t up to the job (sloppy fit, etc.) so there was quite a bit of wander on the cut.  This meant a lot of time spent with a plane trying to recover a uniform thickness.  My intention had been to rip to 1/2″.  In the end, as a result of the wander in the cut, it ended up at about 3/8″ thick.  In then end it worked out okay, but what I’d expected to take me 1 to 2 hours ended up taking the better part of the day.  In hindsight, I should have cut (pardon the pun) my losses and ripped two new pieces with a better fence arrangement.  Anyway, here it is during glue-up.  This is close to the longest thing I can glue in my workspace. 🙂  GluingBatten_smaller

With Fairing1_smallerthe batten made, it is on to lofting proper – the first time something vaguely boaty shaped will appear in the shop!  The first step is to lay down the sheer profile (side-view) based on the height above the design water line (DWL) at each station, taken from the drawings.  With the points plotted on the grid, the batten is used to join them in as fair a curve as possible, tweaking the the locations a tad if necessary.  Even though the batten ended up thinner than I’d envisioned, it seemed to work out well.  It is edge set here, and seemed to be a good stiffness in that arrangement.  This picture is mid-process.   Towards the center  there’s a bit of un-fairness which I was eventually able to get out.

Finally, with the curve fair, it is drawn in.  Since the various views (profile, plan, and body) will all be superimposed, I got some colored pencils to aid in distinguishing which lines correspond to which views.  Profile=Red.

So with that, Ta-Da! The sheer profile! (NB: The only hope you have of seeing it in these pictures is to click and open up the full-size view.)


Sheer Profile From Bow


Sheer Profile From Stern

Something Every Week

They say that one of the keys to completing long and challenging projects in your spare time is to do everything you can to do *something* every week.  Even if all you have time for is something small and seemingly insignificant, it’s important for the psyche to feel that you’re making progress, however slowly.

The past week or so has been busy with a house guest and a trip over an extended Labor Day weekend so there hasn’t been much time for the project.  Nevertheless, in a couple of hours here and there I’ve finished constructing the lofting floor and put down a couple of coats of paint in preparation to begin lofting.


Next I’ll lay down the grid and start assembling some long battens for the lofting.

Start of Work and First (Small) Oops

Today I spent a few hours cleaning up the space where the build will happen and laying down a floor of sorts (1/2″ OSB on 2×4’s) on which to loft the lines of the boat.  Lofting is the process of scaling up the lines from sheet scale (in this case 1:8) to full-size so that patterns can be made of the critical section shapes.  These will then be used to construct a building frame around which the hull will be planked.  The OSB floor will be a substrate on which I will put down 1/4″ Luan painted white which will be the canvas for the lofting.

Everything got off to a good start and I was in the groove when I discovered that somehow I’d messed up my count of how much lumber I needed to lay down the floor (oops).  So, at the end of the first day of actual work, I have a cleaner workspace and 2/3 of a lofting floor to show for it.


My goal had been to get the Luan down and painted today, so I fell a bit short, but nevertheless it felt good to be off and running.  It should now be a quick job to get the rest of the materials and finish the lofting floor.

A Birthday Turns a Dream Into a Project

When I was growing up there were two things I dreamed of doing.  One was to build a Caterham Seven and one was to build a boat.  The Caterham Seven dream was spawned by an article that appeared in a 1986 or ’87 issue of Car and Driver.  I’d never seen one before and as soon as I read about it, I knew that I wanted one.  For about the next decade I made a point of seeking out every article, photograph, or mention that I could find.  The boat dream had a more gradual gestation; the seed planted by Dad teaching me to sail, and then nourished by family trips to Cape Cod, bareboat charters, and boat shows.  It was always lurking in my mind and would manifest itself in various magazine subscriptions, book purchases, etc. but it always seemed much farther off.

Caterham 7Fast forward 14 or 15 years from that first Car and Driver article and, by some good fortune, I’d managed the Seven dream. Assembled in the little 1-car garage at my apartment in Cincinnati, it’s been a joy for the last 12 years and the catalyst for various adventures and friendships.

CaterhamDJ2To me, it is the purest expression of the notion of “sportscar.” Anything not essential to the task in eschewed in favor of simplicity, performance, and driving involvement. No A/C, heater, radio, or power seats/locks (actually no locks full stop). No brake booster, steering assist, ABS, or traction control.  Two seats and just enough of a boot (it is British after all) to swallow a weekend bag.  Other than that, it’s you, your companion of choice, and the road.

All of this forms the backdrop for the highlight of my 39th birthday this year when dream #2 took a giant leap towards reality.  Judith (aka Companion of Choice) graciously bought me my first set of boat plans.  The boat of choice is Iain Oughtred’s Sooty Tern, a 19’8″ open sail-and-oar boat inspired in part by the Sheltand yoals that plied the waters of northern Scotland.  The plans actually consist of the detailed plans for Oughtred’s 18’2″ Arctic Tern with a couple of additional sheets showing details for stretching the additional foot-and-a-bit.


Much of what appeals to me about this particular design is that, as the Seven is to pleasure driving, it represents a minimalist approach to pleasure boating.  No outboard, no cabin, no winches.  If the wind dies, the oars are deployed and the crew is put to work.  For over-nighting in a secluded spot somewhere, a tent is erected, either on the shore or on the boat.  If a change of scenery is desired, it can be easily trailered to unfamiliar waters.

As a first-time boatbuilder, the project is daunting.  It will be at least an order of magnitude more demanding than what amounted to assembly of the Seven.  In future episodes I will attempt to chronicle the process, warts and all.  Happily, I have a very supportive partner who is as excited about my undertaking the project as I am.  One only need consider that buying me the plans for my birthday was her idea, not mine. Thank you, Jude.  I love you.