Building an Adirondack Guideboat-Hanging the Garboard Plank

The nascent hull is just about ready to begin planking.  Hanging planks on a traditionally built guideboat is the most difficult task when building one.  Since it has been three years since I built my last boat I feel a bit rusty.  Will the nuances in planking that I learned by trial and error back then come back to me?  My apprehension is well founded as you will learn as we go along.

Before I start planking I must attend to some final details of preparing the hull for the planks.  The ribs and stems are now attached to the bottom board, the spline is in place, and the hull is braced.  Now I must shave away the leading edges of the higher numbered ribs so that the planks will land on a flat surface and not a rib edge.  I start with a spoke shave to knock down the leading edge of every rib that needs it.

Shaving away the leading edge of a rib to provide a flat landing for the planking.

Here is where my sanding long board comes in handy.  It spans several ribs and ensures that they are all in line when receiving a plank.

Using the sanding long board to ensure that the higher numbered ribs are all in line to receive planking.

The final effort before planking is to lay out the position of each plank on every rib.  I have a series of “tick tapes” do do this.  They are paper strips for each rib with the location of the trailing edge of each plank marked on them.  Here I am laying out the plank trailing edges using the tick tapes.  The Pony clamp is holding the tape to the rib.

Using tick tapes to layout the planking.

The garboard is the first plank to be hung.  I was puzzled by the term “garboard” so I searched for its origins on the Net.  The term comes from the Dutch words “garen” (gather) and “boord” (board) which when combined became gaarboord.  By the early 17th century it had evolved to garboard.

The garboard plank is the easiest to hang on a guideboat for two reasons.  First you don’t have to fit it to a previously hung plank, an enormous plus.  You need only to cut one bevel on the side of the plank opposite the bottom board. Since the next plank must conform to the garboard you don’t have get its width just right.  Any deviation in the garboard plank’s width of up to an 1/8 inch or so will be made up by the next plank.  The second reason is that the bottom board side of the plank gets planed down to the level of the bottom board.  That is easy to do since it doesn’t have to be exact.

So I laid out the garboard shape by spiling.  I found that spiling didn’t allow for enough upward sheer near the stems.  This is probably because the last rib where you can strike an arc when spiling, number 11, is some distance from the stem.  So my first attempt at laying out the plank didn’t work,  The next time around I accounted for the amount of sheer and I was successful.

Fitting the stem end, or hood end, of the plank takes patience.  It must fit as closely as possible into the stem rabbet. I get a close approximation to the shape of the hood end using my template for the stem rabbet.

Checking the hood end with the stem rabbet template.

I use my sanding long board to shape the hood end until it fits.

Shaping the hood end with the sanding long board.

Next, I cut the bevel.  I layout a 5/8″ line down the plank and then cut away the majority with a block plane.  I finish up with a cabinet scraper.  It gives me more control and takes off any rounding that may come from using the plane.

Cutting the bevel with a block plane.

I then hang the plank temporarily and cut away as much of the overhang of the plank on the bottom board side as I can.  Here I am using a small flush cut saw which didn’t work very well.  I tried using a chisel too but I didn’t find the perfect way to do this.  You just have to be patient.

Cutting away the excess plank on the bottom board side.

Now I walk unsuspectingly into a trap.  All four planks are ready to be hung but I must provide a scarf joint to join them.  The position of the scarf is always on top of a rib.  This hides the interior side of the scarf and provides a nice landing for it. I was unaware of this tradition when I built my first guideboat so the scarfs on that boat lie between ribs.  After almost twenty years of hard use their location has not been a problem.

So I marked off where the scarf was to fall on one of the planks and cut it along the line. Remember up front I said I felt a bit rusty.  Well I marked off the plank on the trailing edge rather that the leading edge where it should have been.  So when the plank was hung it was left flapping in the breeze, so to speak.

What to do? Well, there is nothing to do but scrap it.  Hours of work down the drain.  Then I remembered Bunny Austin’s advice to his nephew Keith who had just tried to hang a plank and had it crack on him.  You might remember that Bunny is a fine guideboat builder who comes from a line of six generations of guideboat builders.  Bunny told Keith to find himself a “crying chair” and get it out of his system.  Here I am with my crying stool getting my dumb mistake out of my system.

On my crying stool with the scrapped plank.

Not all was lost.  I had a perfect pattern for the successor plank.  And I might just be able to modify this plank for the number eight plank round.  It takes three planks on each side for that round and this might serve as the middle plank.  We’ll see.

Finally comes the time to permanently hang the garboard planks.  I apply a line of Sikaflex 291 LOT bedding compound to the bottom board and stem rabbet and fasten the planks with screws located at the center of each rib.  Screws are also located at the hood end and along the bottom board edge at 1 1/2″ intervals.

Bedding compound has been applied to the bottom board and the step rabbet.

Here I am laying out the screw positions along the bottom board edge using a compass.

Laying out screw locations along the bottom board using a compass.

Then the screws go on.

Fastening screws along the bottom board edge.

So here is the garboard plank hung on the hull.

Garboard plank hung on the hull.

And here is the scarf done correctly.

Scarf on the garboard plank.

Next time tacks!  There are about 4000 of them in a guideboat.

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