America's Most Historic Yacht

Progress through June 2010

Posted By on September 21, 2010

Large wooden boats are built from the backbone up.  Everything that comes after the backbone is laid depends on these parts being exactly in the right place.   If the backbone was flat, this would be relatively easy; just draw a straight line on the floor and follow it.  The problem comes when you have parts of the backbone that rise off of the floor.  In situations like this, it’s critical to keep everything lined up, even when it’s off of the floor.  This is where a laser comes in handy.

This laser can shine a vertical beam, essentially a plane, with great precision over long distances.

Claes starts with the laser set on a platform that has a centerline exactly lined up with the centerline of the boat.  This line on the floor is directly under the center of the boat.  With the laser starting off from this line, all he has to do is carefully adjust it left and right until it’s exactly on the center of the keel.

With this done, Chris can move forward and make sure that the forekeel and stem are lined up on the vertical beam.  The large angled posts to either side of the backbone are anchored to concrete pads in the floor, and can be shimmed to move the backbone until it’s lined up perfectly.

As high tech as this system is, the centerline that everything comes from was first laid out the way they’ve been laying out centerlines for hundreds of years:  with a taut string .

These days the string it brightly colored to make it easier to see.  The one in the photo above is orange.

With a precise vertical line (the laser) in place, the forekeel, forefoot, and stem can now be assembled and moved into position.

These parts are given a good coating of tar along their mating (also called “faying”) surfaces.  The flexible tar will bridge and waterproof any gaps that open along these surfaces as the wood shrinks and swells.

These parts are all clamped together as solidly as possible while they are being lined up.

A long diagonal brace holds the stem in place while it awaits final fastening and bracing.

While Claes, Chris and Leo work on lining everything up, Eric has been working on the futtocks.  Remember that fancy beam saw?  Here’s what it looks like in action.

The beam saw doesn’t do the final cuts on the futtocks, it just gets the builders close to their lines and removes a lot of waste wood.  This makes it much easier to do the final cuts using the ship’s saw since there’s less wood to heave around.

The ship’s saw can make accurate, beveled cuts that change along the length of the part.  If the guys didn’t have this saw, they would be forced to lay out all of these bevels and cut them by hand.  While the outer (convex) faces could be done somewhat quickly using a power planer, the inner (concave) faces would have to be roughed out with the beam saw or adze, and finished using either a power planer with a curved sole, or a compass plane.

Multiply that by hundreds of futtocks and it becomes quickly apparent that a ship’s saw is more than worth the cost.


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