A Little cleaning and a Little Glassing
The last weekend in March was beautiful.
Saturday morning I went over to my friend's house and whipped out a bucket of
bleach water and the hose and proceeded to scrub the trampoline until it was a
brilliant white. We also scrubbed the hulls, removing the water line from the
sides and the dirt from the top. Mr. Boat looked TERRIFIC!!
Well, aside from the gouges still there from bouncing off the trailer. Here's one.
Quite a difference between the clean hull and the dirty one, eh?
SO... we take off to Columbus Lake to go sailing. Not the best lake... used to
be farmland until TVA built a dam here 50-odd years ago. So you can still look
down and see the occasional tree here and there... In some places they poke up
out of the "lake."
And... we're off! Just gotta get that rudder down.
I know, I know, the sail is dirty.
So we sailed around, having a swell time...
...when not dodging the bass boats everybody was driving around...
What's the point of those things? Is a 225HP fishing boat necessary?
VROOOOOOOOOOOOOOOOOOOOOOOOM!!!!!! ...cast...reel reel reel
reel...VROOOOOOOM!!!.
...and suddenly our turning efficiency was greatly diminished. I note a log
ahead.... I throw the tiller to one side. We continue in a straight line. I
throw the tiller to the side several more times as the log looms large...
finally we begin a gradual turn which is mercifully sharp enough to avoid the
lumber. We remain confused as to the reason for our new maritime understeer.
Finally we return to the beach to meet up with Ahab's wife for some pictures.
Can you find the problem in this next pic?
Look carefully.
About the time that pic was taken, I said "Holy cow! No wonder we couldn't turn!"
Anyway, we sailed a while longer, being mindful of our capabilities and then decided to call it a day. With the boat out of the water, the problem is obvious:
Can I get an "eek!?"
So now I'm thinking "great... new rudder... $100." Ahab suggests building one.
I'm intrigued. I'm also wondering if $100 wouldn't be easier.
Ahab seems excited by the prospect. "Besides, it'll give me a warm-up before I go back to work on my airplane."
"Okay." He convinced me.
That night we carefully measure the other (good) rudder and input all the data into AutoCAD. The file is available for download
{DWG
(93kb) or
DXF (348kb) format} if you're interested in using it to build your own rudder.
You'll also have to print it on legal-sized paper to get the cross-sections
scaled properly. Anyway, in the morning we went to Wal-Mart and Lowe's. When we
got back to Ahab's house, we cut out the cross-sections and used
3M Super 77 Spray Adhesive to glue them to thin sheet-aluminum. Then we
ground the aluminum so that it made a perfect foil. While doing this, we also
used the Super 77 to join the two pieces of fake-flower-mounting foam
together.
Foam and foil cross-sections
The sections were then attached to either end of the piece of foam and Ahab broke out his hot-wire rig and his battery chargers. This is a nifty little setup for cutting through pieces of foam.
The wire gets hot and goes right through the foam, making a clean & smooth cut.
First we cut the foam to a tapered shape as you can see in the next picture;
only slightly wider at either end than the foil cross-sections.
Cutting the foam to shape
Me with the finished foil
When this was done, Ahab cut the piece of oak I bought at Lowe's to fit the top
part of the rudder. While he was doing this, I was cutting and sanding the
foam foil to match the other rudder. Then I just cut one small triangle of foam from a piece of
scrap to finish the form. I mixed up some
5-Minute
Epoxy and glued the whole thing together. A fine way to end the day.
The new and old at the end of the first day of work
The next day we finished smoothing the rudder and then began to coat it with epoxy. We used Ahab's expired epoxy from his airplane project.
He doesn't want to trust his life to a wing made of expired epoxy. The consequences of a failing rudder are far less severe than a failing airplane wing.
Since we want the fiberglass to stick to the foam, we deliberately chose a foam with large pore size so that lots of epoxy can soak into the pores.
Once the foam was saturated and the oak was very wet-looking, we laid a strip of unidirectional fiberglass ("uni") [image] along the thickest part of the foil. After
carefully coaxing all the air bubbles out from under it, we laid a sheet of bidirectional glass ("bid") [image] over the whole rudder. Then we put two layers of uni and
another layer of bid, and finally a piece of bid that just covered the oak and overlapped a few inches onto the foam. The
lay-up took a few hours because we were
careful to coax out as many bubbles as we could to enhance the strength of the completed rudder. When we were finished laying up the glass, we put a layer of "peel-ply"
over the edge of the top piece of glass to smooth the boundary. So any given
part of the rudder has between four and six layers of fiberglass covering it.
We let that cure overnight, and then due to a busy schedule we had to wait a few more days before we could lay up the other side.
The layup has cured. You can see pins holding the glass to the "bottom" of the rudder for curing purposes.
All the excess glass you see there had to be trimmed away.
Note: it didn't cure this way - I flipped it for this picture.
So we used a Dremel with a reinforced cutting wheel to trim away the excess glass/epoxy. While I was removing that glass, Ahab melted 3/4lb. of lead to use as a weight in the tip of the rudder.
Then I cut out the foam around the outside of the rudder and a circle for the weight. We mixed up some flox (epoxy and finely-shredded cotton) for use as
filler. Then we filled in the edges with the flox and epoxied in the lead weight.
The flox and lead in place
Then we had to work quickly - we began the lay-up of the glass on the side you see in the above picture. We wanted to get the glass on before the flox cured
so that it would form a strong bond with the flox, thus creating a thick structural element around the periphery of the rudder - structural contact all
along the area of the flox rather than just over the oak and along the edges of the foam part of the rudder.
For some reason this side took us longer - lots more bubbles to work out. In the end, though, I think we met with very satisfactory results on both sides:
The completed layup on the second side. The peel-ply is very visible here.
That side cured, and then on Saturday I again used the Dremel with the cutting wheel and then a sanding wheel to remove the excess glass you see very obviously
in the above picture, and remove any trace of a seam between the sides. Working with fiberglass is a very itchy business, because when you're sanding, all the "dust"
is actually myriad tiny shards of glass. Every night I took a hot shower to open up the pores in my arms in hopes of releasing the fibers. That helped some.
The new with the old, now very strong if not very pretty
When the seams were gone (pic above), we mixed up some more micro into a peanut-butter (or toothpaste)-like
consistency and smeared it all over the rudder as if we
were frosting a cake. The idea is to fill in the weave so that you can sand it smooth without going into the glass fibers and reducing the strength of the
lay-up.
Kinda looks like frosting, doesn't it? Doesn't it?
The micro cured overnight and in the morning Ahab put a second layer on. When I arrived at his house in the afternoon it had cured too, and I began the tedious job of sanding.
At least this time I was just sanding off epoxy dust and not more itchy glass. I started with 60-grit and worked up to 120 and finally to 320-grit. The result was an extremely smooth
piece of composite material:
Almost ready for paint!
Again using the other rudder as a template, we drilled the mounting holes (slightly over-sized) and then swabbed more epoxy on the insides of the holes with a Q-tip to
seal out water and provide slightly more strength than would be provided by the oak and glass alone.
When the epoxy had cured to the non-tacky but not-yet-hard stage, I pushed the
mounting bolt through several times to make the hole size just right. All in
all, we let that cure for an hour and then took the rudder
and saw-horses far from the cars and used some white
epoxy appliance paint to spray a thick coat of white on one side. I think it
really looks great! Hope to do the other side here
in the next day or so, and then give the new rudder a test this coming weekend!
The varying colors in this pic are due to the garage lights and sun being different "whites."
On to Part Four
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