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I have to admit up front that after figuring the potential loads on the rudder for the steering gear I was more than a little intimidated by this part of the project. The thought of this blade hanging 6' below the hull open to the hazzards of the sea supported only by a plastic tube that I made.
The choice was between a machined stainless rudder stock and carbon fiber. Either would have cost in excess of $3,000 to have custom fabricated but the stainless stock would have added more than 100 pounds to the aft end of the boat. I had developed a fair confidence in my vacuum bagging ability so I decided to tackle the carbon stock myself. It is not a simple round tube. It is more or less rectangular tapering towards the bottom and aft to match the lines of the blade. The layup schedule varies to match the expected stresses and two round bosses match the bearing sleaves.
John sent me full scale Mylars with the blade lines and two sets of station cross sections for the stock. The laminations of the stock are formed around a core of H-80 Divinicel that I had to carve to to fit one set of cross sections that were reduced from the finished size by the thickness of the required number of plys.
 I cut the station templates from 1/4" masonite taking care that they were all exactly the same height and fixed them to a form board. The stock could then be laid in the templates periodically to check the profile as I carved and sanded. I don't have any pictures of the core being carved but this is a picture after the first couple of carbon plys were added.
The plys alternated between several layers of heavy unidirectional laid lengthwise and two layers of lighter weight uni wrapped diagonally in oposite directions.
Wrapping wet carbon fiber around an 8' long pole single handed proved to be sonething of a problem. I ended up drilling the ends, inserting bolts and mounting the stock on between to vertical boards. That way I could rotate the stock as I wrapped.
The wraps had to be very tight because the pressure from the vacuum bag compresses the plys and any slack bunches up in the corners, the most critical area.
 For the same reason no more than one set of plys could be bagged at a time. I could lay only one set of vertical plys and one pair of wraps before bagging. Each bagging required a wrap of peel ply and bleader. Then remove from the pivots and slip into the bag.
It took 12 baggings to complete the stock . I managed to get an average of 3 cycles out of a bag so it took quite a bit of vacuum tape to complete. Each session took about 2 hours from start untill the bag was pulled down and another hour to strip the peel ply and clean up.
All together there is about 50 hours of work and $400 in material in this piece. No wonder the custom made carbon stocks are so expensive.
The next step was to post cure the stock. Post curing Proset requires a fairly exact heating profile to about 150ºF in stages over 12 hours, an 8 hour soak and gradual cooling. There are very few people in this world who need their own personal post cure oven but if you have been reading this website regularly you know by now that for me, this presented an irrisistable challange.
 The oven itself is just a box made of 2x4s and fire retqrdant gypsum board. It is 8' long, 4' high and 18" wide on the interior. I packed the walls with fiberglass insulation and covered the outside in cheap 1/4" plywood. It opens from one end and the side to make loading easier. I found 4 2 KW heating elements on Ebay and mounted them on asbestos shingles at the bottom. To aid circulation I added a long shaft to an old attic ventelation fan and mounted it through the top.
Next I had to find a way to control
 it. I found a Fuji temperature controller that can be programmed for two profiles of 5 ramp/soak steps each. One profile was set up for heating and the other for the cool down. With a thermocouple the total cost was $165.
I mounted the controller in an old disk drive case with a solid state relay, power switch and duplex receptical. The controller also has an RS485 interface so I added an RJ45 jack to the front. Using the boat shed's network cable I can adjust and monitor the oven from my computer in the office. I also recorded the actual post cure profiles just for my records.
The core of the blade is also H-80 Divinicell. This was a great way to use up lots of odd shaped scraps left from fabricating bulkheads and other parts. I epoxied 4 layers of 3/4" Divinicell and carved them to shape with a Sureform, belt sander and ROS. The core pieces were first tabbed to the stock with wide strips of unidirectional carbon fiber and faired in with a mixture of epoxy, silica and milled fiber.
 The rudder was then cantelievered off of a pair of sawhorses and covered with the first two plys of bidirectional glass.
After bagging the blade was cleaned up and checked against the masonite tenplates. In order to keep the plys as close to profile as possible I divided the laminations into three baggings. By laying up the skins directly on the rudder I have avoided any seams so that hopefully, unless I bash into something, there will be no water intrusion.
One final ply of 6 oz woven glass and the rudder was ready for final fairing.
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