Rudder(case) part 3.

I managed to reshape + laminate the leading edge of the rudder, so I could continue with the rudder case. Couldn't find a proper 4 mm thick plastic to mold the case. Instead I wrapped the rudder with the frontrunner fabric, and put two thin hard plastic sheets on top of that. Tried to mold the edge of the flanges with clay, but wasn't satisfied and instead just used an epoxy fillet (also handy to keep the mold plates steady). Once the case is out of the mold I can round off the fillet on the inside of the case.

It worked out well, although the case may be a tiny bit too 'loose'. I'll probably have to make the plastic block at the back of the case 1 mm less wide, to squeeze the case a bit together.
Couldn't think of a good way to put the glass spacer plate in the center of the molded case, and just guesstimated when I glued it on. To glue the tube properly alligned to the spacer plate, I put the case upside down on the rudder and used a piece of tube as can be seen in the picture below. I'm sure this method is not very accuate, but it was the only way to allign the tube I could think of.

In the meantime I'll also work on the centerboard. I wanted to use western red cedar as a core, but changed my mind when I found out in the Netherlands this is not the 'economy option'. Divinycell is cheaper. I think it's quite a big blade; should be easier to shape and laminate than the rudder.

Rudder part 2: FAIL

I laminated all layers (2 c-layers with the carbon sandwiched in between + extra layer round leading edge and top) in one go, hoping this would give the most compact laminate. Next time I won't, and just do one layer at a time. All the glass in one go is difficult.

Although the laminate itself came out ok, to my dissapointment the leading edge of the board has a much too big radius. I didn't take into account enough the thickness of the 3 layers C: to get the profile right I should have shaped the leading edge much more precise than I did.

I don't feel ready to throw away the rudder. Instead I'm busy shaping the leading edge again, this time hopefully right, and then re-laminate the front end of the rudder. Because I have to remove almost all the glass from the front till the carbon uniderectional, the carbon won't be totally enclosed by C-glass anymore (I mean: the layers under and above the carbon are not connected to eachother anymore on the front side), so the rudder might be less strong. I'll take the risk.

Rudder, part 1

I could found enough scrap foam to glue a blank for the rudder. Between the two halves I put some glass to make the blank a bit more stable.

Then I glued in the spar. I used fir (or was it pine?) as a core for the spar. Ian Farrier said that's ok, as long as you wrap the spar with the specified cloth.

Here is the blank with the still unsheated spar.

And here I'm gluing the spar in. Some small blocks under the spar (hopefully) keep it centered in the blank. I put some weights on to keep the blank straight while gluing.

The blank is initially shaped using a router. Grant used the same method. I've never shaped a rudder before, but I thought it went quite well this way.

The routed blank looks like a mess......

...but is actually not too hard to shape. I put some marker lines in the corner of the routed areas, and then it's easy to sand down. Just keep on sanding until the lines start to fade. I mostly used a surform to do the rough work, and a longboard to finish. In this picture the top half is nearly done. I was surprised how small (thin) the board is; because it's so small it feels like every mm mistake really counts - and it probably does.

End result so far: blank with 'HD' insert (mahagony) at front end. At the whole back of the blank, and the low tip of the blade, the foam is removed and replaced with putty. I also made the HD fill at the back with putty. This is easy to do because of the layer of cloth in the middle of the blank.
The rebate for the uni-directional with the spar in the middle of it make up a big portion of the whole board, and it feels like all the careful (ahem) shaping has been waisted. After glassing I'll check if the profile is still anything near the real thing and if not try to restore it with fairing compound.

Primer (finally)

I'm finally busy putting high build primer on the top exterior. This time I'm not spraying (too much hassle + needed a lot of thinner) but just rolling. I apply two thin coats in one go: this primer hardens so quickly after applying you only need to wait 15 minutes to be able to roll the second layer without messing up the first layer. I'll sand this layer down (grit 80-120), touch up the last spots (which show much better with the primer applied) and then apply one more layer primer which I'll sand with much finer grit.
One thing I learned is it is easiest to do as much rough sanding as possible within 24 hours. The primer is already sandable without clogging the paper too much, but not as rock solid as it becomes later.

Cockpit area cleaned and ready for primer. I'll try to finish this this night.
The corners in the cockpit-area will be high gloss and very visible. To get them nice and even I put on a new fillet after fairing the flat parts of the cockpit. Not much work and I think it will look quite good.

Some advice for builders shopping for hardware: if you've built up your bow (as I have) you need a trailer-U-bolt with VERY long legs to make it to the inside of the boat. I couldn't find a suitable U-bolt and will for the time being be using a simple eye epoxyed to a piece of M10-rod.