Ama Flipped

A couple weeks ago I flipped the ama over and started work on the interior.  

The keel panels needed taping with two or three layers of fiberglass.  Fillets were applied to the keel seam and the bulkhead intersections.

A final coat of epoxy went over the seams and interior.  I went with West's 207 special clear epoxy resin as it contains less amine which is beneficial to the barrier coat.  Also added 422 barrier coat compound.

The ballast tanks were then post cured.   It is suggested that the barrier coat should be heated to 120F (49C) or above for four to eight hours.  I piped hot air from a small ceramic heater into the space.  If you place the the heater inside, the thermal safety circuit will shut the machine down repeatedly.  I also added two 125W infrared light bulbs.  250W bulbs are available, but I was fearful of burning things in the small area.  This setup kept the temperature between 130F  (54C) and 155F (68C).  I clamped the lights to shine on the protruding tops of the bulkheads separately.

Task time: 110 hours

Total project time: 770 hours

Ama Progress

The ama has been making good progress.  The keel panels went on.  Next the seams got cleaned up and filled where the wires had been.  The wire holes were closed.

A main task before moving on was fairing the chines, bow and keel.

Here is a bow filled and capped with a thin strip of glass.  I wanted to fully close the seam.

The bows and keel were about 20mm wide when joined.  The square shape did not look too sleek, so I decided to add a foam nose piece. The top picture show the foam glued over the glass, while the bottom is after shaping.  This is Divinycell H80.  It is strong, though I worry about cosmetic damage in minor bumps.

On the keel, I used the same concept with a strip of plywood.  The plywood has the corners on one edge rounded over.  A thin bullnose was then ripped on the table saw.  #17 finish nails are place prior to gluing.  The nails will act as alignment guide once the strip is wet.  Tape at 2 inch intervals worked pretty well as clamps.  I used fast hardener and added a little 5 minute epoxy to get the glue to stick and kick faster. This is a trick off of the West System site.  Sanding then faired it into the keel panels.

Here is the glass draped and partially smoothed.

The intersection of the bow and keel fairings.

The cloth has been wet out with a roller.  This shows how the bulkhead tabs were glued to the hull panels.

Here is the hull drying prior to the first fill coat.  The skirt will be trimmed off of the shear before the epoxy fully cures.  The skirt is also handy for catching epoxy runs during wet out.

Task time: 50 hours

Total project time: 660 hours

Attaching Ama Panels

The last week has been a lot of gluing, filleting and sanding on the main ama planks.  After wiring things into place, I did an initial glue up.  Using a small syringe, I put a bead of thickened adhesive epoxy along the bulkhead plank intersections.  A small syringe allows you to force a bit of epoxy between the two surfaces.

The area should be cleaned up with a chisel stick to avoid excess sanding.  The seam and any remaining glue still needs to be sanded back dull.  A wider fillet is then put over the corners to provide most of the strength.  I used larger syringes for applying a fillet bead.  Many people use pastry bags, but the corners were a bit tight for my hands and a bag.  The fillets are then sanded a bit. The sanding is mandatory in the ballast tanks, as they will get a couple more barrier coats of epoxy over all the seams.

Stem wired for glueing.

Initial glue joint between bulkhead and plank.

The plans call for solid wood inner stems behind the bows.  I had some black walnut around which has a very high compressive strength and does not weigh a lot more than fir or laminated plywood blocks.

Shaping the stems was pretty ad hoc.   You don't really know the dimensions and angles until the panels are joined.  Once the panels are joined, there is not much room for measurements and visual inspections of the inserted pieces.

I decided to go with two parts per inner stem.  I figured that any inaccuracy in tapering and shaping could be taken up by sliding one wedge forward past the other into the small vee area.

The stem pieces during shaping.  In addition to the vee shape, the leading edge curves a bit.

Dry fitting the inner stem.  The pieces did not end up perfectly symmetrical, but it should be strong.  You can see where the stringers come together at the bottom of the picture.

Task time: 28 hours

Total project time: 638 hours

Dry Fitting first Ama Hull Panels

I got the bulkheads firmly attached and then moved on to the main ama panels.

These were wired together at both bows and then dropped as a envelope over the bulkheads.

Some of the bulkhead tabs required sanding to fit into the slots. The glass and epoxy had widened them.  Future builders may want to skip glassing the tabs as much of it is sanded away.

Things fit together pretty well and the outboard, unsupported stations dropped into place.  The stringers provide plenty of support for the bows at this point.

The next step is to taper the insides of the stringers where they meet at the bows.  I took a conservative amount off of these on the bench, but they are still wide enough to hold the panels apart at the deck level.

Task time: 6 hours

Total project time: 616 hours

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