Adventures in cardboard & carbon

Since we’re saving time making the bow sprit from aluminum stock, that eliminated the anticipated fun of trying to make a carbon fiber tube. But we found an outlet – the six foot steering connection rod you’ll see soon between the new tiller pivot point and the rudder cassette.

I don’t have much success getting all-around-glassed parts off the mold or mandrel, So thought we tried the method where you start with a thin fiberglass layer and make a lengthwise slit to get the new tube off the mandrel.

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Once this thin tube was free, we rewaxed the mandrel (which was a piece of metal electrical conduit) and slid the tube back on with the idea that the finished carbon layers would not get stuck to the mandrel. Since we’re “free styling” on this project and it’s the primary steering linkage (a REALLY important part) it seemed that five wraps around with 9oz unidirectional carbon was prudent. Well that many layers of hot epoxy plus the vacuum bag smashing it in and no PVA mold release, etc meant no way was that finished piece sliding off the mandrel. So we made another slit and went back and resealed it afterwards. The result is a pretty thick tube that is comforting-ly stiff when you lean hard on it with no flexing.

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The only metal in the steering system will be stainless steel nuts and ball joints embedded in each end of this tube, plus the bolts to connect pieces. Everything is built now but the rudder bearing I bought isn’t right and needs to be replaced. So stay tuned for the completion soon on that project.

And now to cardboard… It’s not the most elegant way to dream up bathroom cabinets but it works for us. The trick here was designing around the hand pump for the Lavac head and the big mounting brackets where the port side forward beam bolts to the center hull.

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If you’re wondering, it takes six quarters of NFL championship games to cut, recut and generally fiddle with angles to get that mockup done. (poor Packers!) You’re seeing 14 panels that need to be made, adding up to roughly 4′ x 6′ of surface area. Large sheets of double sided laminations were curing on the vac bag table during the two football games.

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And today began the cutting and fitting, like solving a big jigsaw puzzle. One nice trick for cabinet face openings is lining up center points of 4.5″ hole-saw cuts and connecting the arcs.

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It’ll probably take a few days to get this all built out, as there are many intermediate curing steps on adjoining all the panels.

$#!? rolls down hill

The bathroom is never big enough, right? Because our hull bottom is so skinny, the head compartment is cramped and every inch of space needs to be used efficiently. So what goes under the toilet – well, the holding tank makes sense. Thank you Mike L for insisting on that one :). One wants the “black water” tank as large as possible for lazy cruising days, so as to minimize trips to the dreaded pump out station. Rather than buy a expensive, too small tank, we made one that fills the space available. First the blank canvass …

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Now line it with plastic, but NOT like this. Using the loose bag produced nasty ripples along the bottom. Had to cut those out and redo with form-fitting plastic tape instead applied to the hull shape.

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The L shape means the tank is both under your feet and under the toilet base.

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That whole unit lifted out after some prying, and the top pieces were made on the vacuum table. Along with some heavier laminations for the floor and shelf that will sit just above the tank.

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Rather ugly for my first ever tank build, but it held water under testing.
The outlet to the sea is at the bottom, while the inlet / dock pump out, the breather vent, and a spare clean out port sit on top. Rather than installing an expensive and wire-consuming monitor system, there’s a visual level gauge on top – a window we won’t inspect too closely!

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After sealing it all up, the tank slides in place. The hull-facing wall is inset 3/4″ to allow for a bonded-on high density bolting flange (on the wall, not the tank) that will take the weight of the toilet and user, as opposed to actually pushing down on the tank.

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The black pen circle is where the toilet will sit on the shelf just above this tank, but the toilet is not connected to the tank. An exit hose runs from the back of the toilet, up through a pump and a loop up above the waterline, then down in to the tank. The good news is this design means no waste stays in the pipes, which is usually the cause of nasty smells. We’ll see the head installed and the shower floor come together in the next post, and maybe some cardboard mockups of vanity counter / cabinets.

Back on deck, we hung the near finished boom in place and set up the Delta Vee main sheet. Well… The long-tiller steering isn’t going to clear so it makes sense to build a linkage steering system. Messed about with the geometry today until getting the right pivots and control arm lengths.

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The steering action is fast and the tiller throw much shorter; this is a much better solution than the first, including a nice way to attach an electronic tiller pilot independent / redundant from the wind vane system. Farrier’s plans call for all this gear to be inside the aft cabin, but I saw that on a completed F39 and it really interferes with the cabin living space. Other owners would not like the steering gear exposed on deck, but I like the simplicity and obvious inspection ability of the gear in plain sight. Thinking of using a flanged rudder bearing to anchor the tiller pivot, and some combination of carbon bars and stainless steel rods & ball joints for the linkage. Type 304 SS ball joints are easily found – thinking we’ll use those and carry extras vs. hunting for rare type 316 SS ones. Any comments back about that?

Steering complete

The 9′ long steering tiller fit in to the rudder cassette head to complete this project. There is still cosmetic work to do, but it’s nice to know we could pilot the boat now if all this rain keeps flooding the county.

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The tiller makes a full sweeping path across the whole cockpit to get the desired 50 degrees of swing from extreme port to extreme starboard. I think we’ll assume this is comfortable and take it out sailing. But if we find either we want less tiller movement in the cockpit or that the rudder is too limited by the tiller hitting the tower legs, then we will retrofit a linkage system, something like this one on F25c Mojo:

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There are two more primary carbon fiber parts to build, the float-hulls chainplates and the 8′ long bowsprit pole. We’ll start on the plates once the shroud end Terminators get here from Colligo. And this box arrived today for the pole – 20′ of 50″ wide carbon uni to be done in a wrapping fashion and add up to the target wall thickness shown in the F39 plans.

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We’re pretty excited about that little bit of blue plastic; it’s 10′ of shrink wrap sized to fit over the laminated pole and get heated for a nice even squeeze to hold all that carbon in shape. This $240 shipment, plus a pint or so of epoxy, should yield a pole as good as the +$1k cost pre-built blank tubes. Hopefully this shrink wrap idea works as well as the company’s snazzy how-to website.

30 seconds with Anton

To review, months ago we decided to launch with a gas outboard motor instead of an inboard diesel. But there’s been gnawing angst about having the permanent gas tank inside the main hull and all the associated piping. So yesterday during Anton’s first visit to the shop he dives right in to my current “roadblock” issues. On the gas tank, it takes a half minute of looking around to ask, “why aren’t you putting it in that big cockpit coaming box?” Brilliant solve!

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We grabbed some quick measurements before hitting the fish taco place; turns out there are about 27 gallons in the cubic inches available. A custom tank could go where the green tape is marked.

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After an hour of shabby mechanical drawing, we sent off the bid request to ATL flexible fuel tanks in NJ. They make tanks for racing vehicles, insides of airplane wings, spaceships and other tricky applications. The tank will wedge itself in and be very secure. And the fuel line will travel right next to the wiring conduit tube shown a few months back. Here’s what about 6300 cubic inches measures out like:

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And for the future crew reading this, yes this means the “old” tank space under the galley floor just got reclaimed for beer and wine storage. Jimbo’s wine in a bag will be just right.

Anton and Charlie also solved the steering pivot shaft that would not drop in to place. First was inserting the $60 fancy German bushings.

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Rather than trying to machine away a tiny bit of the stainless steel shaft, we made a sanding bore out of wood, tape and sandpaper, spun by the battery drill. With a half hour of messing about the shaft seated in all 8 bushings and the rudder swings perfectly (not a trace of slop / wobble)

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Here’s the cassette holding rudder #1. Note the forward tilt mentioned in a prior post. And that the rudder hits the shop floor about a foot before it gets down in sailing position.

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And the trim tab rudder #2 can’t have the tab swing unless the rudder is all the way down — that’s an interesting way to “turn off” the windvane effect in the future, ie just lift the rudder up a few inches.

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And now to finish the steering, the turning arm was built.

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The forward end gets the foam dug out to make way for the tiller to slide in.

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A big wedge was then cut from the rear portion so the steering arm could surround the cassette.

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So now all that stuff is ready for the tiller. The foam core got shaped with proper attention paid to the driver’s end – we experimented with shapes until finding the right size for Mrs. Carter’s hand. Happy wife, happy boat, right?

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With Keith’s comments in mind, the hoop-strength carbon lamination is curing tonight and the lengthwise unidirectional carbon will be applied Saturday. By Sunday we’ll finally be steering the boat!

Cassette, side 2

We’re now four days in to the rudder cassette build – lots of steps and the result looks very strong.

Here’s the beginning of the steering pivot axis (green tube)

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That green pipe will be vertical; the increasing angle of the cassette away from the vertical hinge means that the rudder will be tilted forward about five degrees. This is important as the boat rises up on plane and less rudder is in the water, the forward rake helps keep the helm balanced and not get very heavy in the driver’s hands.

There are carbon layers between the tube and cassette, with the rest of the gap filled with foam and putty. (In pink)

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Next was wrapping the pivot tube in to the cassette structure with four more layers of thick carbon double bias fabric – look for vertical lines towards the smaller end. And about ten layers of carbon uni-directional in the two areas that match up to the hull’s gudgeons – see the thicker sections along the tube end.

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Ok, this thing is ready for cut-ins at the gudgeon points and trial fitting tomorrow. Then the final step is building the steering tiller. The tiller stub is a built-separate piece that will get permanently bonded to the cassette. Here it starts with a foam core, about 26″ long:

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This piece was laminated and vacuum bagged with its many carbon layers today and will be fitted to the cassette on the boat tomorrow.

Need to decide whether the 9′ long tiller should be made from wood or foam core and carbon. If carbon, we’ll need to solicit ideas on the fabric layup schedule. Any thoughts?

Better than an 8-Track

I remember fondly the day we tore out the 8track in the Chevette and got a Cassette deck. Dorky car with a Radio Shack tape player – geez. Now we’re getting a carbon fiber rudder cassette on a good boat – I like this a lot better than the high school parking lot.

The cassette is built around the rudder for an exact fit, but it has to be oversized to allow low profile carpet to glue along the inside faces. That gives the rudder a snug fit and abrasion prevention. So to create that 4 millimeter gap it was another trip to the fabric store for some 1mil vinyl. (Wrapped in four layers)

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The photo above shows a wax bead laid along the edges to form a nice radius of the cassette lip.

Made a paper pattern to get the vinyl sized just right:

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The white plastic at the bottom will be the sacrificial break away area in case the rudder strikes something – the cassette is designed with a give-way point rather than destroy the rudder or the stern hull structure.

Then six layers of carbon fabric made an 1/8″ cassette body.

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After the epoxy cured a few hammer blows got it separated from the rudder, and looking good.

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And this is roughly where this piece will mount on the boat, after many more steps to create the hinge for turning the rudder and the attachment point for the tiller. Probably another 20 hours for this primary steering build.

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When rudder parts are curing, work goes on in the aft cabin. Floor, bunks, and closet bulkheads are installed. To get the seat backs to conform roughly to the curved hull shape, this telescoping “Third Hand” tool is pushing the two sides in to shape while the fiberglass dries along the bottom edge and I can go eat dinner :)

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With all the cassette talk, the radio got tuned to 80’s music in the shop all day. Took a break from NPR for AC/DC and Duran Duran sing alongs – hope that’s not the chemicals getting to me!

Wind vane and rudder progress

The shop neighbors who were perplexed by the stern tower were satisfied now by seeing the self-steering wind vane installed. It’s the brown unit in these photos. The actual vane that gets pushed by the wind is in a deeply “reefed” position, tilted way back to fit under the skylight ceiling.

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The rudder control cables come thru the tower shelf and will get tied to the legs and then routed to the (to be built) yoke atop the new rudder’s trim tab pivot pin.

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We’ll get back to those details in a couple of weeks when the rudder cassette is built.

The rudder has been shaped, wrapped once in bi-directional carbon and had the 14 layers of carbon unidirectional cloth added in the recessed channels down both sides of the board. First, here’s a look at how that embedded pivot tube just fits inside the shaped rudder.

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And underneath the white fairing compound you can just see the staggered layers of carbon uni.

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The only unexplained part of the rudder plans is how one would keep the blade’s curve intact over the area that gets cut out of the foam core and replaced by that big carbon-wrapped spine piece. So we have a flat spot there that I’ve had to build back up with fairing compound. I’m doing the fairing work now, before adding the final outer layer of carbon wrap.

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Ok, that side is done and we’ll need a few fairing sessions to finish the other.

While the rudder layers cure, work progresses on prepping the windshield and hardtop for paint, and the floors for the aft cabin and equipment room. Pictures soon.