Although it's not advisable to skip too far out of sequence, I'm guilty of putting off laminating the final outer starboard hull exterior section. Here's the result of my weekends work......8 hours sat; 11 solid hours sunday laying two full runs of 34oz. triaxial glass, resin and peelply. Note 3" overlap section recessed into foam w/ power planer.
Also, In the upper background, you can see my cabin top. In order to preserve shop space, I winched it up into the rafters and tied it off.
Here's the final run of "B" (24 oz. glass) going down over what will be the interior top of the cabin. This photo shows my 10 step lamination technique.
1) lay foam over stringer mold
2) fair all glue joints
3) skim foam with a slurry of epoxy and micro balloons
4) roll wet coat of epoxy over foam using a 3" paint roller w/ 3/8" fur
5) lay glass over wet coat
6) wait until the glass soaks up from below
7) roll another wet coat over glass
8) lay peel ply over wet glass
9) wet top of peel ply with left over epoxy that is on the roller ( this makes it easier to work)
10) work excess epoxy from center to edges using bondo spreader.
Here's a look down the inside of the bow beam. For bonding, I used System three Gel-Magic which is a thixotropic structural epoxy adhesive. It's a pretty handy epoxy "glue" that mixes 2 to 1 like epoxy but it's formulated to turn itself into a gel that will stay put. I spread a decent amount along both bonding surfaces, placed the top chanel over the bottom, rolled them on their side and fixed the bow beam together with temporary screws. The photo confirms that I have 100% internal squeeze-out along the entire length of the seam.
Including building the mold, fabricating the two 19ft. bow beam sections has taken about 16 hours. Considering that I am paying myself 0 dollars / hr, that comes to a total labor cost of 0 dollars. Shown here, after popping it out of the mold, is the 2nd half of the bow beam section. Next step will be trimming it down to spec, bonding the two halves together and skimming the beam with a mixture of micro spheres and epoxy to smooth down the seams and minor imperfections. To eliminate bonding prep work I placed peel ply into the mold top and bottom. Peel ply is my friend.
After bagging one section of the bow beam, I used pressurized air to blow the bag up and then set it out in the sun. Thanks to the green house effect, on a sunny day, the temperature inside the bag can easily reach upwards of 120F.
Here's my helper smoothing down the packing tape along the length of the bow beam mold. The two upper cap beams are in-set about the thickness of what I think the sides will be; thus forming an internal flange. After layup and vac bagging is compete, I'll remove the cap strips and lay up what will become the other half of the full 19 ft. length. Then the two channel sections should fit together and be bonded to form a composite beam that is 7 in. tall, 9 1/2in. wide and 19 ft long.
The one inch thick end grain core insert is now in place. To the left, you can see the piece that I cut out. Again, I used system three polyurethane glue and made sure that it was flush to both the top and bottom surface of the one inch thick core cell deck foam.
The portion of the deck in front of the cabin gets a very high density insert. Here you can see an 8" x 16 in. end grain oak core that will transfer the compressive loads of the mast into the deck, the mast bulkhead and the forward center section bulkhead. Your looking at the under side of the forward portion of the cabin top.
So I've used my oven to form all the foam to fit the cabin top mold. I've used two inch squares of 3/8th in. plywood and sheet rock screws to hold the planks in place. Once all the pieces are "dry fit" together, I found it easier for me to start from the middle; edge gluing the planks together one by one.
I'm using SYSTEM THREE polyurethane glue ( similar to the one part, moisture cure, Gorilla glue)
This is actually the inside of the starboard side cabin top......seen here up side down.
So you're looking into the inside of my heat lamp powered thermoforming oven. It's made from a few two inch thick 4' x 8' sheets of foil backed insulation foam and a total of ten 250 Watt heat lamps......... takes 6 minutes to heat the foam until it can bend easily.......7 minutes and it puffs up into very expensive landfill fodder.....When this oven is on, I have to turn up the radio to drown out the jet engine like sound of my electric meter.
Here's an action shot of the 1 inch foam going down over the cabin top mold.
Here's the core for the forward bridgedeck bulkhead. Notice the 3/4 in. white oak compression member. As shown, this bulkhead incorporates a compression member that helps absorb the loads that will be directed downward into the ship structure from the mast base. This evening, I'll vac bag a total of 6 layers of glass on each side to form the part. When It comes time to install this member, additional layers of unidirectional glass, tape and bedding strips will used.
The Cabin bulkhead consumes the majority of my 8ft. x 12ft. vacuum bagging platform. This cabin bulkhead is 112 inches wide by about 78 inches and is made up of a total of 12 layers of glass ( two layers of 24 oz. tri axial glass on each side of 3/4 inch thick core cell foam) with double strips of uni-directional glass along the edges of what will become the entry door and window openings.
This is one of the largest single flat panels that I have bagged thus far and it required six 1500 ml batches of resin that I mixed and applied one after another. With vacuum bagging, unfortunately, a portion of this expensive resin will end up in a land fill in eastern Oregon because the excess resin is pulled through the perforated membrane that is positioned between the peel ply and the breather medium.
Someday, If I take a 60 ft. wave over the stern, I think I'll be glad that this bulkhead is good and strong. ...... If that happens, it's more likely that I'll wish I was on shore under a palm tree having a beer.
I never thought a 60 ft. shop would seem small but I actually had to lift both hulls up a couple of feet so that I would have enough room to build the cabin mold. Scribing all the lines onto the mold forms using carbon paper and the full size templates is an exercise in patience. I was only able to build, scribe and cut two or three molds per day during the week but a full week end allowed me to set them all up on the strong back and lay down the stringers. Note: I had to resort to using double plywood strips in the high curvature areas. A strip of 5/15 in ply topped with a strip of 1/4 inch ply added up to be close enough to the same thickness as the 3/4 in stringers.
I couldn't resist the opportunity to flip the port side hull up and position it in relationship to the starboard hull. The cabin bulkheads that protrude from each hull are sticking up like fangs. The edges of these bulkheads are 112 inches apart. Note: the port side bow lacks the solid foam stem section so you'll need to use your imagination and pretend you see a sleek pointed bow piercing through blue green tropical waters.
Using the full size cabin templates provided with the plans package, the temporary form frames are being marked onto 3/4 in. chip board. There are about a dozen of these form frames that define the shape of the cabin. Once I cut them all, I'll set them up on the same strong back that was used to create the hulls. When complete, I'll run stringers to create a female mold to which I'll thermoform and fit the one inch corecell structural foam.
Here's a quick way to bond the additional layers of reinforcement glass where the bow cables will attach. I'm vacuum bagging two layers of unidirectional glass and a square of reinforcement tape over the exterior triaxial glass and the high density insert. It calls out for additional reinforcements on the inside as well
Posts
All Comments
