These drifts are exactly like fin neck bolts, and we made them from plain bronze rod stock in the same manner as the bolts. The main difference between the drifts and the bolts is that the drifts aren't threaded. Instead, we make little dings all along the lower third of the shafts using a cold chisel. When we hammer them into the holes we've drilled for them, the dings help to catch and hold against the wood fibers. When you pound one of these puppies in, they're pretty close to permanent.
We use drifts to fasten floors to the stern post. Here's a view that you've seen before:
We fasten a floor on each of those flat spots that have been cut into the top face of the stern post knee. You can see the holes in these areas that have already been drilled for the drifts. We don't hammer them into un-drilled wood, like nails, because they'd split the wood. We don't use bolts here, because that would require us to send a very long bolt through the knee, and out through the stern post. You may recall that the stern post has a round cut out for the rudder on the underside:
It's impractical to put a bolt through that round surface. Much easier to just pin things together.
Backtracking a bit... before we fasten these floors in, we have to cut the notches for the frames that will socket into the keel next to floors. Recall that the whole function of the floor is to provide a link between the frames and the keel. The frames will socket into the keel, but they'll be through-bolted to the floors where they rest up along side them. The notches are just to left of where the floors will sit on the stern knee in this photo.
Ok, so, we now clamp the floor in place just where we want it, drill a hole that's just a bit deeper than the drift is long, and pound the drifts home with a 2# sledge.
Clamping these puppies in place was a bit of a challenge at first. The tricky part is figuring out a way to get a clamp to hold against the sloped, coved, and thin-edged underside of the stern post. The solution was to take a half-round length of oak that fits snugly into the stern post cove, notch it to accept a clamp, and then put sandpaper on the half-round surface so that it would stay in place with a friction fit when we clamped it.
This allowed us to clamp the floor in place while we pre-drilled holes for the drifts.
Ok, NOW we can pound the drifts in.
A little close up of the dings that provide extra holding power. You can see that we've previously countersunk for the fin neck head.
When they're in, they look just like nails from the top.
Ok, pretty rustic, hand made nails.
I think it adds to the charm, and is the sign of a truly hand-forged fastener.
And in a short time, we've got a row of floors fastened to the stern post knee.
Good thing, too, because as soon as we get the floors fastened, the crew that's installing the molds can keep moving forward.
Often when people walk into the museum they want to know if the molds will stay in the boat. That's a perfectly reasonable question if you've never built a boat before, but it took us by surprise at first. I mean, come on... who would put pine and plywood held together with drywall screws in their beautiful boat?? But for many people, it's not even close to obvious that the molds are just there to hold the ribbands and give shape to the boat.
So, in case you happen to be one of the people that would ask about the molds, here's how the process works. We get the molds set in place very accurately, and then we bend long strips of wood, called ribbands over the molds from front to back. This makes the boat look like a basket almost. Since the ribbands are stretched across the molds, and the molds are exactly the shape of the inside of the boat, the inside faces of the ribbands also define the exact inside shape of the boat. We then steam bend oak ribs (also called frames), insert one end into the sockets we've cut in the keel, and force them tight against the inside surface of those ribbands. When the ribs cool, they hold their shape and thus help to define the shape of the boat. When we fasten planking to those ribs, we take the ribbands off one by one to get them out of the way. When we're done planking, we take out the molds, and we're left with a hull that's exactly the right shape.
There you go, crash lesson in boat building.
So, a lot of time is spent getting all the molds exactly right... level, plumb, and in just the right location along the length of the boat.
While some folks have been doing that, the ballast keel plug mold is getting closer to its final shape.
It's a far cry from those first square-edged lifts.
David Stimson, our project leader, has started working out the shape of the transom. This is a tricky bit since it's curved and angled. Here's the mold he made up that reflects the shape of the transom.
A short aside is in order here. David is the GM at Boothbay Harbor Shipyard, and the shipyard has donated his time along with all the wood used in this boat to the project. That's huge. Not only is that a substantial financial investment, but without his expertise, we'd be scratching our heads so much that the floor would be carpeted in hair. The wood we're using does not come cheaply either, and we've been floored by some of the beautiful, wide planks of wana we've been able to use. We've been extremely fortunate to have them sponsor this project.
Where were we? Ah yes, the transom. David had patterned out the shape of the transom, traced it on this fine translucent film (formerly the bag that regatta shirts came in), and used the tracing to cut out some wood for the transom frames.
These frames need to fit this curved shape exactly, so he carves each one to fit the mold.
There's lots of fitting in this operation.
This is what separates new boat builders from experienced ones. Being able to carve out a chunk of wood that sits exactly right on curved form is not a simple task.
Soon we'll be ready to set up the ribbands and steam some frames on this gal!