Tubed

Waterproofing with modeling clay?

I finally worked up the courage to close up the cockpit once and for all by glassing in the fiberglass plate to the top of the rudder tube and to the surrounding cockpit sole.  I kept putting it off because I felt that once I actually glassed it all up, I wouldn't be able to fix any mistakes I made.  Throughout the whole rudder post alignment process, I never had a really good reference point except for the bottom rudder shoe.  Things could have gone wrong alignment wise with both the rudder and the rudder tube and determining which was off (or both) would have been difficult.  Fortunately, nothing did go wrong in the end although I discovered something odd that could have really caused me to screw the whole thing up had I been paying attention.

I started with checking to make sure the new rudder tube connection to the original was watertight.  I stuffed a bunch of modeling clay into the rudder tube where it enters the boat and filled up the tube with water and let it set for about an hour.  When I returned I was happy to find that the water level was pretty much at the same height although a little seeped out the bottom around the modeling clay.  I took some tissue paper and carefully dabbed around the new rudder tube interface and there wasn't a drop.  I'm going to call it waterproof at this point (with the collar glassed in and 7 layers of 9 ounce cloth, it should be).

See anything amiss?

After that, there were no more excuses for delay so I got to work.  I sanded down the entire fiberglass plate on both sides, then the rudder tube, and finally hit the surrounding cockpit sole that I would tie everything into.  

Next, I cut out balsa core to fill the areaween the new core I did last fall and the fiberglass plate holding the rudder tube.  I followed up by cutting some 1708 biaxial cloth to cover the new balsa sections and the joint where the rudder tube and the fiberglass plate meet.  At this point I took a step back to make sure I had everything in place before I actually mixed up some epoxy.  

As I sat on the bridge deck looking aft I felt a growing horror welling up inside.  It looked like the tube was not centered in the cockpit.  Holy s&*^t, what have I done.  I grabbed the tape measure and sure enough it was off by about an inch to port.  How could that have happened, I was so careful with all my measurements from the rudder shoe; I was just stumped.  I had a plumb line perfectly straight from the center of the rudder shoe pin all the way up through and tied to the rafter in the shed.  It was dead straight.  I went back to the house and started googling 'off-center rudders' and quickly found this article on the Alberg35.org site where another owner was installing wheel steering and found exactly the same off center rudder on his boat.  

Ok, maybe it wasn't me, it was the boat itself.  It could be that that the original mold's keel was slightly out of alignment or that the deck wasn't centered on the hull, or maybe something else.  In any event, there really wasn't anything I could do about it.  The rudder post seemed to be aligned nicely in the tube and what really matters is that the post rotates properly in the tube.  I went forward...

I mixed up 10 ounces of epoxy and thickened it up with Aerosil to make a mayo 'like' consistency.  Using a notched spreader, I spread it evenly on the bottom skin of the cockpit and then did the same on the bottom of the fiberglass plate.  I set the plate in place and smooshed it all together.  Then I spread more out on the bottom of the balsa pieces going in place and smooshed those into the layup followed up with using up the most of the mayo'd epoxy to cover over all the balsa and gaps in between the rudder tube and the new fiberglass plate, the new balsa, and the existing balsa core from last October.  

I used the remainder of the mayo'd epoxy and made a filet around the new rudder tube where it meets the fiberglass plate.  Next, I mixed up a small batch of un-thickened epoxy and wet out the biaxial fabric that I cut for the rudder tube and fiberglass plate.  I maneuvered this into place and took care that the filets mated up with the biaxial cloth.  I covered it all with plastic and a few sandbags and muscled a particularly large rock onto the whole thing to make sure that it all stuck together nicely.  I let it all set up for a few hours until it tacked up and then covered the new balsa with a wet out layer of biaxial cloth.  Time for bed.

The next day I came back for the big test: to test install the bronze bushing I got from McMaster Carr and see if the rudder post rotated in the tube without binding.  Because the bushing is almost, but not quite the inner diameter of the rudder tube, I needed to put a set screw in so it didn't slide down into the tube where I wouldn't be able to retrieve it.  I also wanted the bushing to sit proud of the top of the tube so that if I need to replace it, I will be able to do so by pulling the tiller head and simple grabbing the the top of the bushing with a large pair of pliers and slide it out (that's the theory anyway).  

Once I had the bushing in place I had my wife slowly swing the rudder while I checked how it looked at the bushing/rudder stock interface.  I am happy to say that it rotated as smooth as butter.  We switched spots and I swung the rudder and it felt so very smooth in both directions.  It felt as if there was no friction whatsoever.  I'll probably grease the whole thing up liberally for the final installation and call it a day.  

The only concern I have left is the possibility of stainless steel and bronze dissimilar metal corrosion when in contact.  I'll have to keep an eye on it, but I think that issue occurs when both metals are immersed in salt water.  We'll see, but I'm a happy camper for now except for the off-center thing, but I can't really blame myself for that. 

Even with only one layer of biaxial in place I can tell that this setup is going to be absolutely bombproof.  I can hit the tube hard from all directions and I can't feel even the tiniest amount of deflection.  Unlike the wheel steering that the boat once had, this will inspire confidence.  This upcoming week I still have 2 more layers of biaxial going down in the cockpit to tie the whole thing together, but I think I can knock it off quickly now that warm weather is here. 

It already feels seriously solid