Sunday, July 26, 2009

Zenos paradox


Or why it is taking so long for me to finish the hull of the boat.



Zeno was a 5th century B.C. philosopher.
Achilles was trying to catch a tortoise. No matter how fast Achilles would run, by the time he reached where the tortoise was the tortoise had moved a little further. Thus Achilles could never catch the tortoise.

To paraphrase the paradox.

On the first day you complete one half of the distance to your goal.

On the second day and each subsequent day you complete one half of the remaining distance.

You will never be able to reach your goal because there will always remain at least a small distance between you and your goal.







The first plywood hull panels went on fairly quickly. They were pretty big and pretty flat. Before long I was working towards the bow.





As the hull developed more and more curve the panels had to be made shorter and shorter so they could be bent to the shape. Because the panels are curving the straight edges of the plywood could no longer simply be butted together.

To fit nicely each edge had to be gently curved.


The closer I got to the bow.

The more difficult the fit and the slower my progress.





The piece in the foreground is dark because I have soaked it to make it take the shape more easily.


There is more than one way to scarf a cut

The plywood pieces that make up the hull need to be fastened together.


You can butt the ends together and reinforce with epoxy fiberglass.


Or there is the hard way.





When you cut through plywood at an angle the layers of wood form an interesting pattern.


In a previous post What Knot I described cutting a scarf joint in the 1x4 by 24 foot board that was to become the keelson.


Here I am cutting a scarf joint in the 1/4 inch plywood that is to become the sides of the hull.



I have been too chicken to try to get the circular saw to cut the slope down to a feather edge so I finish the job with a plane.




Here are some of the panels forming the side of the hull.




Wednesday, July 1, 2009

Hull


The bottom hull panels of an EC 22 are two layers of 4mm plywood.





Here the first layer is being glued down.






After the first layer is on, a second layer is glued on top.

The joints are staggered.







I used a notched spreader to apply a thin coat of thickened epoxy.





Additives are used to thicken the epoxy to a consistency tailored for each job.


There are at least a half dozen additives that can be used. Phenolic microballons give the mixture I am using the brick red color.





The second layer needs to be held down firmly and evenly to make a nice epoxy sandwich.





Staples, clamps, screws, weights, whatever can hold the sandwich together.












The reason for using two layers of plywood is that up near the bow the bottom panels begin to bend quite sharply.

A single thicker layer of ply would not be able to make the bend. Even the 4mm plywood takes a good deal of force to take the bends near the bow.