Over the past few weeks, the 2nd year students have been working steadily on both Corsair and the Herreshoff 12 1/2 rebuild.
Corsair has quite a history. She was built in 1939 at the Herreshoff Manufacturing Company in Bristol RI as a launch for JP Morgan's 343' (yes, you read right, Three Hundred and Forty Three Feet Long) yacht, Corsair IV, but never served her original purpose. Corsair IV was sent to join the British Navy during World War II, before Corsair was finished, and never came home. Corsair IV ran aground off of Acapulco and her engines were salvagesd to generate electricity for the city... does that give some indication as to the size of the yacht? Jay Picotte has written an excellent article about both Corsair and her mother ship's history in the
Spring 2008 issue of Restoration Quarterly, and it's well worth a read.
Our little Corsair needed quite a bit of work when she came in. She's been completely reframed and the students are working on replanking her from about the waterline down. She is double planked, meaning that there are 2 thin layers of planking to contend with. The inner planking is cedar and the outer layer is mahogany. The garboard plank (the bottommost plank) is full-thickness mahogany.
Here, the students have patterned out the garboard and are installing it.
It's quite the celebration of clamps.
You see the little lip on the top of the plank? The cedar inner planking will butt up to the top of the plank and the mahogany outer planking will lap over the cedar and sit in that step (known as a rabbet).
After the garboard is installed, the students remove the planking up to the level that they'll be replanking, and then begin to pattern out the shape of the new planks. This process is called "spiling."
Here you can see where the planks have been removed as well as one of the new planks that have been installed. The new one is the one that's just below the shiny older planking...
The planking is installed in overlaps; first an inner plank is attached, then an outer one is attached on top of it, with the seam of the outer plank landing about in the middle of the inner plank. Thickened shellac is traditionally applied between the 2 layers of planking to both glue them together and to seal the seams.
Here, the student is spiling out the shape of the next outer plank. The inner plank has been installed, and a line has been drawn on it showing the exact location for the edge of the outer plank. He's using a long strip of white plywood that's been temporarily tacked to the inner planking to copy the shape of the new plank.
You can see the dark pencil line on the lighter cedar, marking out the lower edge of the new plank. The upper edge is defined by the mahogany plank you see installed above. In order to pattern out the shape of the new plank, he needs to have a way to exactly duplicate how the plank will curve from the front to the rear of the boat. To do this, he first tacks the white board to the boat so that it lands somewhere in the middle of where the plank will eventually go. This is called the spiling batten. Next, he hot glues a little rectangle of wood to this spiling batten so that it just touches the underside of the plank above it, and then glues another block so that it just comes down to the line representing the bottom of the plank.
These 2 blocks give the student the exact width of the new plank at that location on the boat. Here he is setting up the next lower block. He first puts a temporary block of wood exactly on the lower plank line.
Then places a new rectangle of wood with hot glue on it so that it just touches this block.
And the glue sets very quickly, holding the block in place.
When you get enough of these blocks glued on, you end up with a long spiling batten that has many points laid on it with these little blocks.
After spiling the entire plank, he'll take the spiling batten off of the boat, lay it on top of some mahogany planking stock, mark the width of the plank using all of these little rectangles, and mark a smooth line connecting all the points... just like a giant connect-the-dots. That will give him the exact shape of the plank that he needs. A little fitting to fine tune it, and violat! A new plank.
Of course, when you take old planks off of a boat, you end up with lots of holes left over from the previous fasteners. These need to be filled before you put new planks on top of them. Take this little area around the transom for instance.
You can see both the holes, and some little plugs that have been used to patch some of the holes. One of the 2nd years came up with a snazzy system to make those plugs quickly.
He made a reamer bit that's shaped exactly like a pencil point to start.
Chuck this into a drill, and ream out an old screw hole.
The hole is exactly the shape of a pencil,
sooo.... if you take some square mahogany stock, put it in the pencil sharpener and sharpen it to a pencil point, you'll get a wood plug that fits your hole exactly. A little glue, a little tap with the hammer, and presto! Instant plug! The fit is so good that you can also pare off the excess wood as soon as you drive it in, you don't even need to wait for the glue to dry.
Here's an oak plug just under the layer of bedding compound up by the stem.
Very creative fellows, these 2nd years.
Now that the boat has been framed and the frames are held in place with the existing planking, there is no need for the forms that were previously placed around the boat to hold it to the correct shape while the frames were bent into place.
So, let's lose those puppies.
Over on the 12 1/2, the students have been riveting the sheer clamp to the sheer strake (the top most plank). Riveting is loud, long work. The process is simple, really. You drill a hole, insert a copper nail in through the outside of the boat, put a copper washer over the protruding nail on the inside of the boat, clip all but about a nail's thickness off, and pound the end of the nail over so that it mushrooms over the washer. You normally use a ball peen hammer to do this, and the process is called "peening." That's where ball peen gets its name from, in case you didn't know. Essentially, you're creating a 2-headed nail. It's somewhat slow, loud, and frustrating when you have to peen over your nail in a tight space where it's hard to swing a hammer.
Enter the impact driver. With a good tool, one can make this process less tiring, but nothing can stop it from being loud. Using a special attachment for an air-powered impact driver, the students can peen over the end of the copper rivet much more quickly than they would be able to were they to do it all by hand.
Here's the nail with a washer (called a "rove") on it,
And here's the driver pounding the heck out of it (sorry, I didn't show them clipping the nail down to the right length).
Other projects are going on simultaneously with the 12 1/2 as well. For instance, here's a student cutting out the shape needed to nest the hardware used to hang the rudder onto the boat.
There's always something going on around here.