Monday, March 31, 2008

V-berth (Making partitions)

I was sitting in the V-berth space, chin in hand, trying to visualize what I was planning to build.
I knew I wanted a single platform with a hanging locker on the starboard side.
The problem was; the hull stiffeners, deck, and previous tabbing all formed visual lines that kept tricking my brain. What I thought was level was sloping radically upwards, what was level, appeared to be diving down at the bow. It was clear I would need some reference lines to get a better picture in my head before proceeding. If I can't "see" it, I can't build it.

I emailed a picture of my interior to John Irving, a fellow Alberg 30 owner who is refitting his vessel. We have been sharing information and ideas and I asked if he could supply me with some measurements of the interior of his boat so I could get an idea of where things used to be in my boat. When I checked my email I was both amazed and delighted; John was leaving for vacation that morning but had taken the time and drove to his vessel to get some measurements for me.
I received four pages of pictures that were covered with measurements and reference points!
I printed the pictures and took them into my vessel and plotted the locations. At last I was able to "see" what had been before, and could visualize what I wanted to build.

It made my week-end!

I placed listings athwart-ship on the forward and main bulkheads to get the height I wanted.
Then cut four 2x4's to length and placed them fore and aft on the listings to be used as reference points for templating the partitions that will go under the V-berth platform/bunk.

The partition was made by clamping a listing athwart-ship under the 2x4's (the 2x4's ensured that the height of the partition was correct). A plumb-bob was used to project the location from the listing to the hull and marked with a felt pen. The partition template was then built using strips of 1/8 inch plywood in the same manner we have used to make all of the bulkheads.

Installing the Main Bulkheads

3M 5200 was used applied to the bulkhead / deck joint and Tyler helped me fit the bulkhead into place and secure it with wedges. It was tabbed to the hull stiffeners and left to cure.

The following weekend Noah helped me vacuum bag the starboard side forward hull stiffeners into place. We left it to cure for 24 hours and then installed the starboard bulkhead. While the tabbing cured we made foam spacers to fill the small gap we had deliberately left between the bulkhead and the hull to prevent cyclic fatigue. We mixed up some West System filleting compound and resin and and applied it to the joint. We used the curved end of the West System mixing sticks to shape it into a radius curve that the biaxial tabbing will be rolled onto.

Sunday, March 16, 2008

Vacuum bagging hull stiffeners

I decided to glass in some Taco hull stiffeners to add some stiffness to the hull. They are made of a stiff but flexible plastic and were very easy to install. When accidentally stepped on they would deform and spring right back into shape, a nice feature when installing them into confined spaces where the odd mis-step is inevitable. Two of us held them in place and drew the location on the hull, then they were removed to the cockpit for safe keeping and the area was sanded with a Dewalt zirconia flap disc. The area was vacuumed several times and the stiffeners were spot glued into place using a hot glue gun. A final sanding was done with 80 grit da disks and the area was vacuumed once more. Mastic was applied around the area to be bagged.
Note: In the picture below the mastic was applied around only one stiffener, we changed this to surround both stiffeners when we realized the bagging film was large enough to cover two at once.

I borrowed the propane tent heater from work and set it up under the boat and ducted it into the lazzerette hatch with 16 inch insulated flex duct. The heater was ran for an hour to warm the hull and turned off during the glassing layup. The temperature of the outside of the hull was taken using an infra red temp gun. The cockpit area was 131 degrees F., the temperature dropped as readings were taken moving towards the bow with the outside hull temperature in the area of the vacuum bagging being 75 degrees F.

The biaxial glass and vacuum bagging materials were cut to fit and placed in the cockpit.
West system epoxy was used and the resin dispensed into several mixing tubs ready for the hardener to be added as required. The first batch was mixed and placed into the wringer basin, a small amount was taken below and rolled onto the area to wet it out.
The cloth was fed into the resin bath and then through the rollers to remove excess resin. This is definitely a two person job! Be sure to tape the leading edge of the cloth to prevent stray strands from winding themselves around the rollers. The cloth is throughly wet out but can held on edge without resin dripping from it. The cloth was taken below, laid in place, and rolled with a 4" foam roller. Peel ply (release fabric), breather cloth, and the plastic bag film were then applied. A small cut was made in the film and the vacuum suction cup placed onto it. This was the first time I had used the vacuum bagging equipment and it was impossible to achieve a vacuum on the irregular hull surface using the mastic alone. After several failed attempts to achieve a vacuum, shrink wrapping tape was applied around the perimeter and a vacuum was created. For the next round of vacuum bagging the area where the mastic is applied will have a coat of west system epoxy thickened with some low density fairing compound applied to ensure a smooth and regular surface for the sealant.

Once the vacuum was achieved the heater was turned on and the tools cleaned with acetone.