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)
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)
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.
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:
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?
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)
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:
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.
After the epoxy cured a few hammer blows got it separated from the rudder, and looking good.
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.
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 :)
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!
It took a few hours today to get the trim tab properly spaced in its rudder slot, after the hinge-area covers were built in carbon. It’s all done now, ready for some final fairing and paint. Now we can build the rudder cassette that mounts on the stern of the main hull. That needs the completed rudder to serve as the mold for the cassette shell. Work starts next week.
Hinge covers starting out in foam core:
Needed vacuum bagging to conform to the tricky shape …
And the result covers the hinge area nicely, hopefully providing clean enough water flow in the neutral (straight ahead) position.
This building method with the hinge tube imbedded at the start and the tab cut out from the completed rudder has resulted in everything lining up just right. (Sure glad I didn’t try to retrofit a trim tab hinge tube in to the first rudder built last year).
PS – the boat sat quiet for two days when Jeanne turned up the house thermostat on the first cold night this fall – yep, the 25 yr old furnace croaked. Saved a bunch of money by doing our own demolition, new condensate drain under the house and building a sturdy new platform for the furnace man to come in as the hero. Final price tag was ironically exactly the same as the boat’s new Suzuki motor. I like the furnace’s 10yr warranty better!
12 hours later that task was DONE! Woke up early, worried about the geometry of the trim tab swing since the top and bottom edges are not perpendicular to the pivot axis. So we invested an hour in a rough mock up.
That wood is cut at the same angles as the trim tab needs to be, and it showed how a gap needs to be left between the tab and the rudder to allow the 45 degree swing. Now it was time to cut for real…
Now it needs some edge smoothing and figuring out some carbon layup to reinforce all the newly exposed edges. Since we couldn’t cut the rudder on a curve around the pivot tube we need to add back some little wings to cover up the hinge, in terms of keeping good water flow between the rudder and the tab. That should be mellow work, coming off the stress of getting this whole thing built and cut right :)
Try this link to see the trim tab in action:
Sometimes the next step in the boat shop is a scary one. Here we have a nice new 6.5′ tall, 32 pound carbon fiber rudder, all faired out to spec shape and ready for paint.
BUT it’s not done – sitting on the workbench tonight all marked up for cutting out the trim tab section on the trailing edge, so the boat can be steered by the windvane up on the tower shown a couple weeks back. So with at least 50 hours of work and about a grand in materials I decided to sleep on it and take one more check of the measurements before cutting tomorrow. It’s so counter-intuitive to take a saw to a finished product, but the windvane company and the naval architect are all on board and eager to see how this thing works out.
Hopefully good photos will get to you this weekend.