Spiling and Hanging the Garboard

Fair warning:  this is a long post.  But there’s good news – it also has a lot of pictures.

Remember what I said in a previous post about boatbuilders and their vocabulary?  Here’s a few more terms:

Planks versus Strakes:  I mentioned previously that the type of construction for this boat is called glued lapstrake, because it consists of strakes overlapping one another. A strake runs the full length of the boat, from stem to transom.  The sheets of plywood are standard length, only 8 feet.  A plank is what I cut from the plywood sheet; I’ll have to join two planks together to form a strake.  The planks will be joined together with a scarf joint, which means each plank will have an opposing bevel.  The bevel is cut at a slope of 1:8, or in other words, for the 6mm (approx. 1/4″) ply I’m using, each bevel will have a width of 2″.  There are several ways to cut scarfs, many use specialized jigs and power tools.  I love using the power tools I have, but sometimes low tech is the way to go.  I cut a practice piece from the ply and made a scarf using the old fashioned block plane.  Better to screw up on a practice than a full-length plank!  The laminations in the plywood helped me make a smooth scarf.

2016 05 07 practice scarf
2016 05 07 practice scarf

Garboards:  the garboards are  the lowest strakes on the boat, attached to the keelson.  They are often also the most difficult to install, because they have a wicked twist to them.  The garboard is nearly flat amidships, but will twist to vertical where it joins the stem.  On my boat the garboards also have a significant twist at the transom.

Spiling:  (verb:  to spile)  the strakes are not straight.  Most are C-shaped to some degree; on some craft they may even have an S-bend when laid flat.  Further complicating matters is that the garboard will not be shaped the same as the strake above it, which will not be the same as the strake above that, and so on.  Spiling is the technique of determining the shape of the strake so that when laid flat on plywood stock, the planks can be accurately cut.  Traditional boatbuilding books describe several methods of spiling planks; the uninitiated may feel that these methods involve some amounts of black magic and voodoo.  Such is not the case, I used traditional methods when spiling the planks on my grandson’s little rocking boat:

Wee Lad, my grandson's little rocking boat, next to Wee Lass.
Wee Lad, my grandson’s little rocking boat, next to Wee Lass.

However, for spiling the strakes on Tammie Norrie, I wanted something as foolproof as possible.  I found a method described on the WoodenBoat forum that fit the bill:  long battens are secured to the upper and lower edges of where the strake will lie, and small pieces of wood or plywood are temporarily tacked to generate the shape of the strake.  For the garboard, I attached one batten to the centerline of the keelson, and the other to the marks on each of the mold I had made when lining off.  The result is a “truss” that I can use as a pattern for cutting out the planks.  I need two planks per strake, but because the strakes are identical port and starboard, I can use the same truss for either side.

2016-04-23 Spiling the garboard, fore
2016-04-23 Spiling the garboard, fore
2016 04-23 Spiling the garboard, midships
2016 04-23 Spiling the garboard, midships

Once the truss is tacked in place, take it off the boat and to the workbench where it can be used to cut the planks.  The planks are cut using a fine-toothed (metal cutting) blade on the jig saw, and cleaned up with the block plane.

2016-04-24 garboard truss
2016-04-24 garboard truss

I chose to cut the starboard planks first, to test the concept, then cut the port side planks later.  Once the planks are cut, offer up to the boat and check for fit:

2016-05-07 Test fitting the first plank
2016-05-07 Test fitting the first plank

The edges of the garboard would be screwed to the stem and the keelson.  I used stainless steel screws on Wee Lass, but this boat would use screws made of silicon bronze.  Because bronze is softer than stainless, I decided to get out my test piece and practice to make sure I had drilled the pilot holes the correct size and didn’t over-torque the screws.

2016 05 08 Practice piece
2016 05 08 Practice piece

I also epoxied the strakes in two steps.  On Saturday afternoon, I epoxied the scarfs for each of the two strakes.  This was done on the boat; I didn’t have room in the garage for a table long enough for the strakes to sit on the bench overnight (I can jury rig something during the day when the weather is nice; Wee Lass will sit in the driveway.  But Wee Lass spends the night in the garage, out of the evening dew.)  The next day I epoxied the strakes to the stem, keelson, and transom, after first covering the edges of the molds with clear plastic tape.

2016 05 08
2016 05 08
2016 05 08 Aft view, hanging the garboards
2016 05 08 Aft view, hanging the garboards

This is a milestone.  The first strakes have been hung.

3 thoughts on “Spiling and Hanging the Garboard”

  1. Al,
    Good luck with your project. I read through all of the previous posts. Very interesting. Thanks for sharing.
    Robert Campbell

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: