Sunday, October 17, 2010


In the Pacific Northwet, er, Northwest we tend to get a lot of rain. Well, that is, ever since the plywood was delivered we have had a lot of rain. In addition, we had had some extraordinarily humid days and nights.

Why am I bringing this up? Well, most lumber is dried in a kiln or in an air environment where moisture is drawn from the wood and brought to a more or less uniform level. This makes the wood consistent from piece to piece and makes it a bit lighter as well.

In my house and especially my garage where I have been putting together unsealed thin wooden panels, the high humidity and dry wood combine to make high humidity and not-quite-but-almost damp wood. This is not good.

1. The wood weighs more than it did from the factory. This means the boat weighs more.
2. When the wood is finally sealed with resin and cloth, that moisture is sealed in with the wood.
3. When the wood is exposed to summer time temperatures that moisture will be expelled from the wood and it needs to go somewhere. This can cause problems with the glass.

What really brought this to a head was when I had made the skirt for the seat from sheets of copy paper. The next day the paper was limper than cooked spaghetti - and the unsealed seat panels had been exposed to this air for days. The stabilizers were exposed for even longer.

While not quite so bad, the rest of the boat panels were in my family room. With the arrival of fall and the turning on of the forced air furnace, the interior humidity of the house was somewhat less than that of the garage and the outdoors.

What is the solution?

Buy a dehumidifier, or wait until the middle of winter.

Yes, the problem would eventually fix it self as the weather got colder and the difference between the heated indoor air and the cold, humid outdoor would bring down the humidity. Still, I wanted to get working on the boat sooner than later. A controlled environment makes quite a bit of difference as there is no guarantee that it will get dry enough until well into winter.

I did some research and bought a high capacity GE dehumidifier. It was purchased online as the local stores either couldn't be bothered to call me back or the models offered were rated as unsatisfactory by Consumers Reports. The price of $218, including shipping, was also the quite reasonable. It arrived last Friday, and has been on for a couple of days in the family room.

At first the humidity in the room measured 75%. Wow! I didn't know it was so high - and this was on a less humid day!

Overnight and one tank of water drained later, the humidity was down to 55%. There was definitely more of a crispness to the air and the cardboard on which the panels sat.

On Sunday and another tank drained, the humidity was down to 45%. The weight of one of the stabilizers was down to 3 pounds, 14 oz. The other was down to 13 pounds, 15 oz. This was a drop of at least 1 oz, as I forget which was the one I had originally weighed.

I'll let things continue to dry out for a week or so and proceed once the moisture level stabilizes.

Saturday, October 09, 2010

Seat Bulkhead

The panels for the seat are not quite enough by themselves to distribute the forces of one pedaling at full tilt. In addition, it is difficult to make sure the seat panels are properly positioned with respect to each other and the deck.

Part of the solution is to make an internal horizontal bulkhead. This will help transfer forces from the seat back to the side and rear panels. It will also help keep the panels from falling inward when the panel edges are glued together with thickened resin.

Since the shape is a bit irregular, I made a paper skirt. While there are probably a dozen other ways to do it, I did it this way.
1. Get a dozen 8-1/2 by 11 inch sheets of paper, an adhesive tape dispenser and a small level
2. Take two sheets of paper, butt them together along the long edge, and apply tape to the two pieces so that you now have a 17 x 11 inch piece of paper.
3. Using the level to make sure the edge of the paper is level, center and tape the long edge of this 17x11 sheet of paper to the seat back about half way up. Don't use more than one or two small pieces of tape for this.
4. While holding the sheet horizontal, take the level to one of the adjacent side panels of the seat and hold one end at the same height where the sheet intersects the side of the seat back.
5. Take another sheet, center and tape it to the side panel so that the long edge is at the same level as the edge of the paper on the seat back.
6. Hold both the 17x11 sheet and the new 8-1/2x11 sheet horizontal. The end of one sheet should overlap the end of the other sheet.
7. Tape the overlapping ends together, taking care to make sure the paper remains horizontal.

Repeat the process going around the seat panels until you arrive back at the seat back.

You should now have an irregular ring of paper, or skirt, that more or less is sticking out around the seat panels at the same height.

Carefully remove the skirt from the seat panels so that the shape is preserved.

You can either use the skirt as-is, or take more sheets of paper, tape them together, and trace the pentagonal hole onto them, and cut out the traced drawing. This makes a simple template for the bulkhead.

Note: Since the hole is taken from the outside of the seat panels, you will need to subtract the thickness of the panels from the outer edges of the template.

Take the template and use it to mark the shape of the bulkhead on whatever you plan to use for the bulkhead, and cut out the bulkhead.

I chose some scrap blue styrofoam insulation that I had laying about. As it turned out it was almost exactly the width of the inside of the seat. It was also nearly 2 inches thick, so the slant of the seat back and the rear-most panels needed to be taken into account.

Using a protractor level (Sears), I measured the seat back at about 60 degrees. The rear panels measured at about 7 degrees. The sides, being parallel, can be ignored.

Using the protractor level I tilted it to 60 degrees with one end at the lower corner of the foam and the upper end towards the interior of the foam. The template was placed at the intersection of the top of the foam and the level. A line was drawn across the foam along the edge of the template.

The triangular opposite end of the template was also traced on the foam at this time.

The foam was now cut. I used a bandsaw as it makes a very smooth, clean edge. It also has a nice tilting table marked in degrees, which made the 60 degree and 7 degree cuts very easy.

Saturday, October 02, 2010

Seat Back Dimensional Adjustment

The photos of the seat back preliminary setup didn't easily show it, but the panels didn't quite line up, and there was a gap of about 0.25" between the top of the seat back panel and the rest of the structure. There was also a gap between the rear two panels. They would not align closely enough to match the triangular top piece.

I ended up taking 0.25 inches off the bottoms of the four seat side panels with the belt sander, and sanding down the angled edge where the back two panels meet. This was quick work with the bench belt sander.

This now allows the top of the seat back panel to rest against the top triangular piece for some additional back support, and all the pieces now meet with reasonably flush edges.

I took some pictures of the seat pieced together, but not yet glued.

I think I can glue the entire seat back together in one go, using thickened resin.

I haven't figured out a good way to clamp it together. The paint can technique seems to be OK in holding the seat back and sides in place, but the back two pieces don't comply - in particular at the top. The top edges like to skew inward or outward at the least provocation.

Stitching it might be a solution, but there would likely still be some play.

Adding a slightly smaller triangular plate to the inside bottom of the top triangle piece is a standard woodworking trick that could solve this. I just might give that a try.

Fitting and refitting the panels, and trying different ways to set it up for gluing took about an hour.