America's Most Historic Yacht

Planking season

Posted By on February 5, 2014

It’s going to be planking season for quite a while now. Sorry for the long delay between posts, but here we go.

As of November, the garboard (the first and lowest plank on a boat) was being installed. Here’s the starboard forward end.

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Louie Sauzedde has joined the crew working on planking.


He has a series of informational videos that you may find interesting under the heading Tips from a Shipwright on YouTube.

Louie was fairing the deadwood by the sternpost when I stopped by the shop last November.


Everyone has their own take on how to spile planks, and Louie is no exception. Spiling is the process of transferring the shape of a plank as it’s laid out on the boat to the raw planking stock. It’s part of a multi step process that goes like this:

  1. Lay out the plank lines on the boat. The plank locations are marked out along the length of the boat using long, fair battens. This allows the builders to step back and see how the planks will eventually look. Any wiggles, flat spots, or unfair lines are addressed here. The edges of the planks are drawn onto the frames.
  2. Spile the planks. This step copies the shape of the drawn planks onto flexible stock (often thin plywood) that can be removed from the boat.
  3. Copy the spiling pattern onto the plank stock. In this step, the spiling pattern is laid down onto rough stock, and the shape is precisely drawn.
  4. Determine the planking bevels and draw them onto the stock as well. Planks rarely have square edges since they attach to surfaces with flare and hollow. In order for two planks to butt together tightly, their edges need to be beveled.
  5. Cut out and bevel the planks. Cut a slight caulking bevel along the edge to allow for later caulking. Shape the inner face of the plank to lie snugly against the frames as need be.
  6. Steam the plank if needed (usually just for areas with twist or curve).
  7. Attach the plank to the frames with just enough hanging spikes to hold it solidly in place.
  8. Drill and trunnel the plank to fasten it to the frames.

Phew. And you thought they just threw those suckers on.

There are 4 spiling methods that I know, and I’ll show you a couple of them. All spiling methods use some kind of flexible wood as a base It’s often plywood, but it can be anything that fits easily against the frames. This is called spiling stock. The spiling stock has to fit within the edges of the plank that it’s copying. The stock is tacked onto the frames, and the locations of the plank lines are copied onto the stock. Some people do this using a compass like this:


The point of the compass sits right on the plank line and a curve is drawn onto the stock. When that spiling stock is placed on the plank wood, the curve can be used to re-create the exact location of the compass point (and thus the location of the plank line) onto the wood.

Some people like hot gluing little wooden fingers onto their planking stock.


The tips of these fingers are placed to just touch the plank line. The nice thing about this method is that it’s easy to copy the pattern onto the plank stock by tacking down a batten that just touches the tips of each of these fingers.

The compass method is a bit slow, and the finger method requires making lots of little fingers and messing around with hot glue. Louie likes a third method. He uses sticky file folder labels as fingers.

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This method is quick, inexpensive, and you can easily rip the old fingers off and replace them with new ones to reuse the spiling stock.

By the end of January, the planking was marching right along. Here’s a butt joint with the caulking bevel clearly visible below it.  The bevel opens up from the line marked on the plank.


A butt joint is where two planks butt up to one another at their ends. These joints are commonly located on frames so that the end of each plank is solidly fastened into a frame.

Here you can see the hanging spikes (dark) and the trunnels (light) holding the planks to the frames. The hanging spikes are large bronze square nails that hold the plank in place until they are fastened with the trunnels.

Trunnels (short for “tree nails”) are wooden pegs, usually locust for rot resistance that are driven though the planks and into the frames. A small wedge is driven into the end of the trunnel just before it’s pounded home to add extra gripping power.


This plank is from the Charles W. Morgan whaling ship. Coronet’s planks are a little nicer looking…

Often planks are steamed before they’re attached to the boat. Steaming softens the wood a bit and makes it more amenable to twisting and curving. The usual way to do this is to build a steam box, pipe in hot steam, steam the plank (1 hr. / inch plank thickness), carry the hot plank to the boat and clamp it in place. After the plank has cooled for about a day, it’s fastened to the frames.

Louie decided to try steaming the planks in place. He bagged the plank, clamped it to the frames, and piped steam directly into the bag. After cooking for the proper amount of time, the bag can be removed and the plank clamped again to the frames.

Here’s his steamer in action. It’s a section of double walled stove pipe with a coil of copper piping inside and a burner below.


Water feeds through the copper pipe, flash boils, and comes out of a rubber hose as you will see.

In this video, Louie has just gotten the generator going and it’s kicking out steam like there’s no tomorrow. He plugs the hose into a pvc pipe that goes into the bag and spreads the steam out along its length through a series of holes. You can see the white pipe inside the bag here.


Unfortunately, the pvc was softened too much by the steam, so the pipe / hose connection failed. There’s more than one way to do this, however, including just putting the hose directly into the bag. We’ll see how the system has been modified during the next visit.

In the meantime, here’s the planking progress so far. Starboard:

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Leo brings in a plank for spiling.


The overhead crane is priceless.

Up top, the deck furniture is in place and the tops of the frames have all been tied in at bulwark level.

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Erik has been forging the bronze hanging spikes.

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A few of the finished products.


Until next time!



7 Responses to “Planking season”

  1. Bob Easton says:

    THANKS Tom!
    Updates about Coronet are always welcome.

    I really like Louie’s fast and inexpensive spiling method.

    Thanks also for the videos.

  2. E.Wrann says:

    Always enjoy these posts. My great great grandfather was a crew member on the Coronet during its race with the Dauntless in 1887.

  3. Randy solt says:

    While I understand planking season is a long process. Maybe we could see a few updates on how the season is progressing. I love following the restoration and am excited for her to become more like her normal self. I am sure I am not alone when I say we could all use a few snap shots of the planking process.

    Thanks so much for the dedication to this vessel.

  4. admin says:

    Hi Randy,
    It’s been tough getting up to Newport to keep this current as we’ve been finishing up the whaling ship Charles W. Morgan here at the Seaport. Now that she’s downriver and ballasted I’ll have more time to get up to RI and get these updates coming again. Sorry for the long delays…

  5. Randy Solt says:

    Thank you Tom. Look forward to it. While I dont know much about ship building I do enjoy looking at this. do you have any info on the whaling sip that was being finished up? thanks again and will keep coming back.

  6. admin says:

    I’ve got lots of info on the whaling ship since I’m one of the shipwrights involved in her restoration. I’ve only been on the project for the past 2 1/2 years (out of 5), but I’ve been writing a blog about the rebuilding for the past 2 years or so. You can see it here:

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