The Keuka Whaler - Part Four

By Craig Hohm - The Finger Lakes, New York - USA

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Planking the whaleboat - Spiling


The spiling batten is a flat piece of wood that fits on the boat mold within the confines of the space defined by the plank measurements; the batten should be somewhat overlong; you spile the curve beyond the actual length of the plank pieces so that the scarf is fair.

Spiling batten

The spiling batten should lie flat on the mold; the clamp nearest you shows a small spacer to bring it down flush with the planking batten. The blue tape shows the position of the anticipated scarf joint. Using a compass, trace arcs along the length of the spiling batten using the lap line as the reference.

Compass arcs to determine upper plank line

Transfer vertical measurements to the spiling batten at the ribs and spaced intervals, writing down the distance between the lap line and the planking batten every 12” or so: 6-1+ in this case at station 4.

Vertical measures of plank thickness

When all these measures are done, take the spiling batten to the plywood planking stock. Using a smaller batten, join the arcs on the spiling batten into a matching reference curve by driving nails where the arc meets the edge of the small batten.

Connecting the compass arcs

Draw the line , mark the interval vertical distances on either edge of the spiling batten.

Transferring line to planking stock

Then transfer the arcs onto the plywood, allowing for width needed on the final plank. Redraw this line using the small batten to the outside of the nails, and then measure the interval vertical distances off the small batten.

Using batten to draw line on planking stock

These points become the bottom edge of the complete plank, and are connected with the small batten as a fair curve guide.

Scribing lower plank line with batten

Cut it out and plane it to the line. I like to clamp it to the bench and use a hand plane and then finish with a stanley 95, to ensure a square edge.

Cutting to the line
Clean up with stanley 95

This is important because the final step involves copying this hard-won plank using a pattern bit router, which takes about 5”.

Copying plank pattern

The whaleboat requires 4 spiled pieces per side


Now the plank pieces need to be joined together with scarf joints; these are beveled to a 1:8 slope. One could glue up all the scarfs and then glue the plank on; I have found it more convenient to do the two end scarfs, fair them, and then do the middle scarf as the plank is glued on; this makes it a one man operation. Lay the plank sections on the boat in position and mark the overlap (3” in this case for 3/8 “ plywood). I like to write “s” on the surface that is scarfed and “no” on the side that is not (been there, done that mistake).

Marking scarf overlap

The planks are then stacked with the scarf sides up and planed together. This picture below shows about how far I am willing to go with the power plane.

Roughing out scarf

It is then finished up with hand planes.

Finish scarf

The uniform ply sections show it is flat and fair. Now the two sections of plank can be glued together while aligned on the boat. Don’t forget to tape the lap bevel (clear plastic packing tape) at the scarfs, or you will be cutting them off. After the glue is dry the edges are cleaned up and, if there is any unfairness to the appearance of the edge line, it can be smoothed out on the bench.

Clamping scarf

Some tape leaves a residue on the bevel; be sure to clean it off so the epoxy will penetrate.

Rabbets 2

Finally the rabbets are cut on the plank edges. With the planks clamped in position on the boat I mark the overlap of the lap line and then cut it out on the bench. The depth here is only a 1/3 of the thickness, giving more strength to the outer side of the final rabbet joint.

Cutting plank rabbet

Take it down to somewhat less than you think you need, and put it on the boat to see how it is coming.

Finishing stem landing

Also at this time do the final bevel on the stem; the landing surface on the stem needs to be flat so that the plywood is not forced to bend in two directions. Place a block plane on the stem bevel surface and rock it to find the high spots.

All that needs doing now is marking and cutting the final scarf, rounding the inside edges of the planks halves, and sealing the inside edge with two coats of epoxy; this sealing step saves time when it comes to finishing off the inside. Also seal the bare wood of the the faired ribs with two coats

Some notes about epoxy. I use WEST and have been very satisfied with it (and their customer support line), but at times the coated surfaces will develop an “amine blush” which prevents paint adherence. It is easy to wash off with just water but forgetting to do it will, in the words of one of my instructors, “hurt your feelings”. Epoxy also forms precipitates if it get cold, so I keep my containers on an orchid warmer mat in the winter. Chose your hardener for the operation: I use “fast” when I am doing multiple coats in a day, and “slow“ when I want working time (see plank gluing error above). Mix it in smallish batches (6-8 oz) and plan on using it up before getting more. It is also possible to conserve glue by, for example, gluing half the plank down, collecting squeeze out, and using this residue to continue gluing. Epoxy is expensive. I also place the foam roller and brush from the first sealing coat in the freezer while waiting for the coat to dry so I don’t have to saturate another roller for the second coat. I clean up with vinegar which works well and is far more pleasant (and cheaper!) than alcohol or lacquer thinner.

Before the final glue, mark the rib landings on the plank pieces (glue goes there too ), and lay out glue along the lap line and its mating surface on the plank. Don’t forget to retape any areas of the molds that were marred in the fairing process so the planks won’t stick to them. In the final glue up I put the bottom scarf piece down first; I saturate the scarf with unthickened epoxy before spreading out the thickened glue.

Gluing aft piece

Sight along the scarf to make sure the line runs fair; It can be tweaked a bit after it dries with a shoulder plane if needed. The stern photo shows a scarf, marked with a pointer.

Gluing fore piece

To my eye it looks a little high there, and maybe I should take off a 1/16 or so just for looks.

Here’s the final appearance.

Clamps in place

When the glue is dry I put screws in the stem ends and at the ribs; Some designers say it is unnecessary, but it makes me feel better.

Screwing to ribs

You will note my use of so-called antique tools. Most of these tools I have from Ebay. They are cheap (where collectors have not taken notice of them), fun to use, and highly functional. The Yankee screwdriver for example, allows rapid screwing with subtle control, just the thing for fragile bronze screws where a power driver might mar them or snap them off.

The final photo shows the lay out of the last three planks.

Final plank layout

The interior is next.


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