Team Seacats

I made my first, and last, rudder out of the new rudder mold.  The result was pretty good.  Although I brushed in an early thin layer of epoxy in the mold with the intent of holding a nice outside finish, I didn’t let it cure enough before vacuum bagging the carbon and the vacuum sucked the still-to-soft resin out leaving some pinholes between the carbon weave.  After trimming away the rest of the pieces, I put in some filler but will probably have to make another pass to get it right.  I filled the core with a thick epoxy / microballoons (tinted dark gray) before sandwiching the two cured skins back together in the mold.  The rudder looks good and while it is probably about average in weight, I think I can cut a little more weight out of it.  The brass rod itself weighs as much as the rudder so first step would be to find a lighter alternative.

Oh, the reason for the “last rudder out of this mold”?  The newest mold-half warped badly while cooling after I left it in the sun curing the rudder.  I’m getting tired of looking at this rudder mold and don’t think I’ll remake this half again until I need another rudder.  I think maybe I laminated the mold too thickly in one step…or something.  Might have to talk to some folks to figure out how to keep this from happening again.

I also worked out the bulkhead and radio tray material.  I took some light weight PVC foam and ripped out a .25″ thick sheet from a large block.  I then planned the position of the main servo winch and using a razor blade, cut out the foam to receive two balsa blocks to provide something to screw into for the winch servo mounting.  I then vacuum bagged one layer of 5.7oz carbon cloth using epoxy resin to each side of the foam.  It’s amazing stuff.  The whole sheet ways a touch over 2oz and is enough to make the main bulkhead and the radio tray.  I admit to being a little stumped for a while trying to figure out how to template the bulkhead without a ton of trail and error fitting.  I finally decided to utilize the hull molds to make a template so I marked the position on the molds with electrical tape and laid up two layers of 1″ fiberglass tape in the same area where the bulkhead will be inserted into the hull and used those to trace a template on the foam core carbon material.  After trimming the carbon, I fitted the bulkhead and with only some minor cleanup of the resin where I had placed fixtures inside the hull it fit perfectly.  The bulkhead is flat on the bottom leaving an opening for water to drain out of the front of the boat should there ever be a reason to do so.  It will be much easier to perform the assembly of the shroud connection points and mast compression post in one step next time.
 

  

I’ve also been trying to sort out how I can mount the keel trunk and get it accurately placed.  Obviously a jig of some sort would be great but I need to have the first one setup to jig anything.  I decided to hang the boat from the stern and the bow and use a level to sort out squaring up the keel.  For the fore and aft measurement, I measured the height of the waterline at the bow and the stern from the floor getting them pretty level (I know where the water line is from the computer design and verification through the float test we did several months ago).  With the keel trunk attached inside the hull to a long aluminum bar (that will later be in the center of the future keel foil), the bar acts like a pendulum and as long as the hull is level fore/aft and side/side, the bar will be plumb where I want it.   I’ll glue up the main bulkhead and the trunk together at the same time and fit the radio tray in as a sub-deck reinforcement to the keel trunk later this week.  It should be very solid.