A Project Named Clancy - III. Setting Up The Jig

The jig assembly (illustration from Build a Clancy)

Clancy is built on a jig -- a form that holds key structural elements in the correct position in three dimensional space so that they can be attached to each other.  The jig for Clancy is a 10-ft x 3-ft ladder frame made from 2x4s, with a vertical plywood "crutch" to hold the bulkhead and transom, a plywood center mold to give shape to the boat's midsection, and a piece of timber at the forward end of the jig for the top of the stem to land on. 

When building Clancy, it is useful to have both a copy of one of the Clancy books, and the drawings from the New Yankee Workshop.  The books contain step by step instructions and details not contained in the New Yankee plans/videos, but the New Yankee plans are superior than those in the book.  The New Yankee draftsmanship is better, plans for all parts are condensed to two sheets of paper, plywood layouts are included, etc. 

Test fit of the crutch and centre mold

Laying out jig parts

I started by marking and cutting out all of the plywood parts for the jig.  A 4'x8' sheet of 1/2" plywood (not marine grade!) is required for the jig.  I had a spare sheet of AC laying around that I used.   If not for having the plywood on hand, MDF would probably be a better choice, being easier to mark up precisely.  I used a combination of a measuring tape, carpenter's square and straightedge to lay out the parts.  Having a long T-square and metal straight edge rule would have made the job easier and more precise. 

Outer perimeter of the frame. Note the Eastport
Pram draped in plastic below. 

The next step is to assemble the ladder frame.  The rails of the frame are 10-ft 2x4s, and the rungs a 3-ft lengths of 2x4, spaced per the dimensions in the plans.  Having very straight timber here is beneficial.  With the way the coronavirus pandemic has disrupted the lumber market, it was hard to find straight 10 footers at the local big box store!  All joints are reinforced by 12-in plywood gussets.  The plans call for gluing all joints, but between the gussets and attaching everything with screws, the frame is brutally strong, so I omitted the glue (which also makes it easier to disassemble later).  

Completed ladder frame

At this point, it is worth talking about the situation in the Lee Boatworks Shop.  It is full of boats.  In a space just the size of a very small 2 car garage (maybe a 1.5 car garage), there is a kayak on the wall (Redfish), a kayak on the ceiling (Pygmy), and a kayak in three parts on the floor (CLC Shearwater Sectional)  There's a rowboat against a wall (Fern), and a small sailing dinghy (CLC Eastport Pram) on the floor.  This is in addition to the shop tools, garden tools and storage typical to a garage.  There is no room to build a Clancy.  To solve this, I added legs and casters to the Clancy building jig, so that the Eastport Pram on the floor could be tucked under it.  So, I am literally building boats on top of boats.

Boats everywhere, and almost nowhere left to 
work! The plywood at the far end is for the jig 
and has already been cut down notably.

In the next installment I'll talk more about marking the plywood parts for Clancy, but it is worth noting that prior to finishing the jig, I found the ladder frame made a great table to hold the plywood sheets when I marked them and cut them out.  A scrap piece of plywood on top of the ladder also made a great surface for coating parts like the daggerboard case and rudder in epoxy.

The jig, now on legs, being used as a work table

With the frame complete (and freed from its duties as a table, the next step was to mark the centerline of the jig.  Marking the center of each end and snapping a chalk line would have worked, but I chose to give my laser level a workout.  

The crutch is cut out from 1/2" plywood, and has several slots cut into it which will be used to hold the center mold, and the bulkheads and transom in the correct position.  Some b2x2 blocking is added at each slot to give a surface to temporarily clamp/screw the bulkheads to.  The bulkheads and center mold slots are vertical, and the transom's is raked 22.5 deg.  Log #1, a 2x2 that is used to attach the crutch to the frame is lined up with one edge along the centerline and screwed to the frame.  The crutch is then attached to this.  This results in the left edge of the crutch being right on the centerline of the boat.  The crutch is held plumb with gussets.  When the bulkheads and transom are later put into position, their centerlines just need to be aligned with the left edge of the crutch, ensuring a straight boat. 

The jig from the behind...

...and ahead (log #3 has not been installed yet here)

The center mold slides onto the crutch and, after being made square with the crutch is screwed down to 2x2's, which are in turn secured to the ladder.  Logs #2 and #3, also 2x2's are aligned with their centers on the centerline of  jig.  Log #2 runs between the front of the jig and the first rung and is used to secure log #3 which is screwed to the top of it.  Log #3 is where the top of the stem will later be attached.

The jig itself was a simple and enjoyable carpentry project, but did take some time to get right.  I worked in a few hour-long sessions on weeknights, and, including the addition of the castered legs, probably spent 6 hours on it.  Everything needs to be aligned with the center of the jig, and squared up, but diligence here pays huge dividends later.