Saturday, January 22, 2011

Big Glue Day

This past week I picked up a foam insulation board from Home Depot to remake two bulkheads that were just slightly undersized. While there I also picked up a tube of Liquid Nails with the intention of using it to secure the bulkheads to the panels. I also ordered another quart of structural fillet, figuring that the original quart would not be adequate to do the entire hull. Lastly, I cut 3 to 3.5 inch wide strips of the 12 ounce biaxial knit cloth to back the lower seams of the hull.

Taking the stuffing box I found it didn't quite fit through the oval hole cut into the hull - at least not at the 14 degree angle. So, using a half-round rasp/file I spent some quality time enlarging the hole, primarily beveling the inside fore and external aft surfaces. This worked quite well.

Today I reassembled the hull. This was necessary to make sure that the new bulkheads fit properly. Some additional sanding was needed to get the bottom edges of the hull to fit to the bottom panel, and to get the cockpit floor panel to properly cover the sides. It was also done to shim the bottom panel to make sure the side panels would properly mate with it from stem to stern.

Once this was done, I disassembled the hull, spread the panels on the benches so that the bottom hull panel was accessible and the two side panels were stacked, with one accessible.

Finally, everything was ready to be glued.

I mixed a small bucket of resin, and poured it along the length of the bottom panel and one side panel. Taking a squeegee I spread it over the surfaces, working it into the grain. As the resin soaked in, the wood changed color twice. First, it changed to an intermediate slightly darker color. Second, after a minute or so it would change to a darker, richer color that was very pleasing to the eye.

The small bucket of resin was depleted before the first side was completely done. Another batch was mixed and applied, completing the surface. It was now time for applying resin to the edge.

For this task I used a sponge brush. It was somewhat messy, as the sponge was fairly flimsy and the resin viscous. There were a few drips on the floor and elsewhere.

Once the first side panel was finished, with resin applied to the interior side and bottom edge, it was put in place on the bottom panel. Paint cans were used to keep it from flopping over.

The second side panel was coated, and resin applied to the bottom edge. It, too, was put in place on the bottom panel, supported by paint cans.

The next phase should have been to apply the fillet material and glass reinforcements. However, the sides refused to stay where they were supposed to be. So, plan B went into effect: Glue the bulkheads into place and apply the fillet and glass afterwards.

I used leftover resin on the sides of the bulkheads. It was starting to kick off, and was pretty viscous, so it stayed in place pretty well. Shrink wrap plastic strips were tied around the hull at strategic places to hold things together. Wedges of foam under the shrink wrap were used to apply pressure were the side panels were misbehaving. Spring clips were used at the bow and stern to hold the tips, and a clamp was used at the stern where the panels wanted to twist to one side.

About two thirds of the quart of fillet material was mixed in the now empty resin bucket. The green and red components turned into a muddy brown goo.

This goo was applied with a small squeegee to the bottom seams of the hull. It was easy to apply too much fillet, but also pretty easy to scrape up the stuff that managed to get spread far from the seam. Once I got the hang of it I was able to apply it along the most of the length of the hull - at least until the squeegee couldn't fit any more.

Fillet was applied to the fore side of the wooden bulkhead as well as the aft side below the deck. It was also applied to the foam bulkheads until I ran out.

The glass strips I had pre-cut were now too long. They had to be cut to fit between bulkheads.

After they were cut to fit the strips were put in place. This was a bit messier and somewhat more difficult as the edges of the strips were rough. When they brushed the side panels they tended to stick - often in not quite the right place. The strips also tended to stretch longitudinally just by handling them, and had to be fattened (stretched laterally) to return to their proper dimensions.

Twelve ounce knit cloth really soaks up resin. It took four large cups to saturate the cloth on the bottom seams as well as the wooden bulkhead. It also took two small foam brushes to do the job as they quickly lost their shape and integrity.

Four hours after I started it was done. Whew!

Saturday, January 15, 2011

Starting Main Hull Assembly

Instead of working on the boat over the holiday break between Christmas and New Year's I took my family to Orlando, FL, to visit theme parks and the Kennedy Space Center. So, nothing was done, with the exception of ordering fiberglass tubing from Nimbus Paddles in Canada, and getting another gallon of resin and half gallon of hardener.

I still have over half a gallon of resin + hardener from the original order, but the next couple of stages will use a lot - and I don't want to run out in the middle of a lay up.

The fiberglass tubes are for several things:
1. 1 inch OD by 0.75 inch ID by 64 inches for the stuffing box. This will allow a prop shaft of up to 0.5 inches diameter, with allowances for sleeve style teflon, nylon or oiled bronze bearings.
2. 1.375 inch ID with 0.1 inch wall by 3 feet for mounting the akas. This will be cut into several pieces, with two short lengths on the amas and an 11 inch piece to mount on the hull to anchor the akas. The extra length will be used as part of the dipping rudder mechanism or grab tube steering.
3. 1.375 inch OD by 1.25 inch ID by 3 feet by two pieces for the akas.
4. An extra 1.375 inch OD by 1.25 inch ID by 3 feet piece for use as a grab tube, part of the dipping rudder mechanism, etc.

I also got a couple of stainless steel push buttons to be used for quick securing or removal of the akas. Some stainless spring ball pins will be used to secure the akas to the stabilizers/amas. This will be just like the stabilizers used on the Cadence, so the stabilizer angle of attack can be easily adjusted on the beach, and the stabilizers can be removed while on the water for docking purposes, etc.

Today I spent some quality time with my ancient Black & Decker 2-1/2 inch belt sander removing the excess resin from the scarfed joints. Apparently the cold temperature in the garage encouraged the resin to stay much thicker on the spots where pressure was not applied from the other panels, so there was a lot to remove.

In the process, however, the toothed belt driving the sander's belt finally wore out and broke, disabling the sander. Oh, well. I bought the thing maybe 25 years ago and used it on countless projects. I guess I got my money's worth out of it!

The trouble is, I haven't seen many 2-1/2 inch belt sanders for sale. The smallest one these days is 3 inches - and they are much heavier and harder to use for intricate or lighter duty tasks such as this.

Rather than give up I chose to use the Sears Professional random orbital sander I bought late last year. Lo and behold - it worked better than the belt sander!

While it took a little longer the results on sanding the resin areas were smoother and with fewer issues. The integrated vacuum pickup was much better at eliminating dust clouds in the shop, too.

The next step was to taper the tips of the bow and stern sides so that they match the bottom panel of the hull. I had concerns that the orbital sander would not be up to the task, but there was nothing to worry about. With a little care and patience it did an excellent job of sanding through the plywood at the proper taper, leaving perhaps half of the outermost ply at the very tips on each piece. Excellent!

After vacuuming and sweeping the remaining dust off the panels, I did an initial assembly of the hull bottom and sides. Paint cans were employed to keep the sides vertical, and the foam bulkheads were inserted at 1, 2, 3, 3.6, 4 and 5 meters to keep the sides from falling inward. The single interior wood bulkhead panel was also put in its place at the front side of the cockpit, but it didn't want to stay in position without assistance.

One really great feature included with these cut-out panels is the scoring done by the NC machine. The different panels are easily aligned by matching the scores on one panel with the matching score on the other. The accuracy achieved is within 0.05 inches - perfectly adequate for this sort of assembly.

The next step is to make sure the bulkheads properly match the taper of the hull form at their stations. This is easily done with a sanding block, and should take very little time.

Total time today, for the removal of excess resin, tapering the panels at the bow and stern, cleaning up from the previous work and getting the bulkheads in position: approximately 3 hours.