Sunday, May 31, 2015

Mounting Ama Stringers

Leading up to mounting the ama stringers on the hull panels, there were several tasks.

Scarfing the fir stringers.  Two scarfs per side.  25 feet each.

Rounding over the bottom edge to fit the CNCed bulkheads.

The stringer is 38mm vertically.  This was just enough heft to require some serious clamping to pull the curve to match the rocker of the shear.  I had to make up 25 of these reusable blocks to support horizontal clamping.

Stringers glued up with the horizontal clamps removed.   There was enough bend that the panel had to be set back away from the edge of the table.  This meant using screws to clamp vertically as most of my clamps don't have a deep enough throat to reach.  The holes will be filled with a syringe later.

Task time: 28 hours
Total project time: 625 hours

Wednesday, May 27, 2015

Ama Ballast Tank Considerations

About a third of the ama volume will be taken up by twin ballast tanks.  The ballast water is held by the hull and decks directly instead of in discrete tanks. This will probably be one of the most abused areas of the boat.  The tanks will rarely be completely dry.  Instead they will be more like a hot, humid washing machine bouncing across the waves. It's pretty important that these tanks are completely waterproof.

Gougeon has published some Guidelines for Wood/Epoxy Composite Tanks.  To summarize,

  • Tanks should have 5 or 6 coats of epoxy
  • The epoxy should be slightly resin rich to reduce microscopic amine deposits trapped in the cured mix.  The amine could act as a tunnel for water.
  • The tanks should be post cured to at least 120F for 4 to 8 hours.
  • Care to avoid amine contamination should be taken in mixing and cleaning cured surfaces.
Since this is non-potable water, I am planning on using 422 Barrier Coat Additive in the last couple of coats.  I could not find much information on 422's effects on bonding strength, so I will hold off on using it until the ama has been assembled.

The panels are currently up to four coats on the interior and are about ready for assembly

Monday, May 25, 2015

Farrier F-32RS

While in San Diego, I ran across Jailbreak.  She is an all carbon Farrier F-32SR.  I thought the boat had a lot of interesting details and some nice areas of fit and finish.  Here is a short slideshow of some of the details.

She had a newly fitted canting rig that was still being debugged.  It seemed quite complicated with hydraulics and the need to adjust both stays at speed.  Apparently it is a major performance boost.

I liked the tramp attachments.  I recently saw a similar set up on Felix, the Team Turnpoint Design cat.

Jailbreak has all synthetic Colligo Dynex Dux rigging similar to what I am planning.

Sunday, May 24, 2015

Ama Panel Prep

Since joining the panels, there has been a couple weeks of work on the table.  There are quite a few steps to be done on each hull panel interior face.  There are six panels.

  • Cleanup puzzle joints.
  • Fill screw clamp holes from puzzle bonding with a syringe of thickened epoxy.

  • Sand panels and edges.
  • Put three coats of epoxy on edges. I found it was easier to get this done before surface coating. 
  • Sheath the inside with 300gm/sqm satin weave glass.
  • Trim excess glass at edges of the panel at mid cure.
  • Hot coat a second fill coat on the glass before full cure.
  • Once cured, sand any remaining fiberglass overhang missed by trimming flush with panel edge.
  • Scrub amine blush off with 3M Scotch Brite and water. Mop amine off the surface with a sponge.  I use a small bucket of water and I change the water as soon as I see any cloudiness from the collected wax.  Dry the panel with a clean towel before it starts to dry.  You want to get any remaining amine off while it is in solution and has not dried back onto the surface.

  • Hand sand panel with an 80 grit flat board to flatten the coat and knock of high spots where epoxy might have pooled.
  • Sand panel to a dull even color eliminating all shiny spots.  This used a random orbital sander with 80-100 grit.

  • Bevel off interior corners of edges where they will be bonded together to form chines.  This allow the wired panels to sit against each other much easier than with sharp corners.  I used a laminate trimmer with a V bit.

  • Vacuum, vacuum, vacuum and wipe, wipe, wipe the panels clean.
  • Recoat the panel with epoxy, scrub and sand four more times.  I switch down to 120 grit on these coats.
  • Stack the panels in symmetrical pairs.  Measure and mark the locations of holes for wire stitching.  These are placed 1/2 inch from the edges at increments of 5 - 7 inches apart.  I want them evenly spaced so that the panels while tighten uniformly.  The hole locations need to avoid the bulkhead placement points where you won't be able to manipulate a wire.   The two panels to be stitched together must be marked at the same places along the chine.
  • Once the layout is correct.  Drill holes through both panels at the same time.  This is done with a 9/64ths bit.
  • Glue the stringers along the main hull panel shear.  There will be a separate post on this.

Task time: 95 hours
Total project time: 597 hours

Sunday, May 10, 2015

Start of the Ama

I started glueing the puzzle joints on the ama panels yesterday.  Hope to get a strong back going within a week.

Task time: 12 hours
Total project time: 502 hours