To add to Pat's comments that "lots of things can go wrong" with
castings...
I did extensive (though amatuer) keel work on hull #478 several years
ago. I chose to remove and sandblast the keel to start at a known point
of healthy bare iron.
My sandblasted keel was definitely not symetric, and had substantial
irregularities. The most interesting were areas of relief that looked a
bit like a coral reef pattern. The largest area was about 12" x 12"
with depth from the surrounding surface of up to 2". I can't say if
this was a casting defect or rust damage.
I borrowed Sally Taylor's template set for a rough approximation of the
desired shape to achieve through filling and fairing, though I admit I
gave up before achieving the shape of those templates. If I recall, the
greatest area of difference between my bare iron casting and the shape
of Sally's templates was in the middle third of the keel vertically, and
the leading third horizontally. The templates indicated a broader
section with larger radius at the leading edge (a better foil, I
believe). In this area my keel seemed to narrow to a thinner section
with a tighter radius at the leading edge.
Joe Anglim
"Hania" hull #478
some day I'll get around to painting the name on the hull
-----Original Message-----
From: tuna-bounces at myfleet.org [mailto:tuna-bounces at myfleet.org] On
Behalf Of Nancy & Pat Broderick
Sent: Wednesday, January 31, 2007 9:02 PM
To: Santana 22 fleet mailing list.
Subject: Re: [Santana 22] keel templates
Calling All Tunas,
I've been out of town since going home from the SSS 3-Bridge early
with my rudder between my legs. Nick and I just couldn't get
"Elaine" (Hull #245) to move forward or point -- even in those brief
bursts of 5+ knot winds we encountered. I went down Friday to hoist
the boat in and then came back Saturday morning to go racing. Turns
out the herring "visited" Schoonmaker Point Marina Friday night. I
got "spawned!" When we hauled the boat out Saturday afternoon it
looked like the hull and keel had been "shrink wrapped in bubble wrap!
Talk about lousy keels!!!!!
I think Eric was the last owner (it was then called "Riff-Raff") to
re-do the keel. I think he did a great job and as far as I can tell
the thing's pretty symmetrical - rudder, too. If anyone has his
email address, he might chime in with some tips.
The keels are cast iron and were made in a packed sand mold into
which molten iron was poured. Molten iron shrinks a little when it
cools (there's probably a technical term for this). It's critical to
make sure both sides of something like a sailboat keel mold are
packed uniformly. Usually the "plug" is slightly oversize to allow
for the shrinkage. Uniform cooling is also critical. If one side
cools quicker than the other, things don't come out evenly. There's
an art to casting. Lots of things can go wrong.
As I said in an earlier email. If you visit the Santa Cruz YC's dry
storage, or the MPYC's you'll see several "variations" on the Tuna keel.
How "flat" is the bottom of the keel?
How "sharp" is the transition from the bottom to the sides?
How "sharp" is the front of the keel?
How "shaved off" is the back?
After Saturday, however, there's one thing I know for sure. A Tuna
with fish eggs attached doesn't go fast and doesn't point. I'm
headed down Friday with the pressure washer and a stiff brush.
Anyone want to check out "Elaine's" keep up close and personal -- and
wet and stinky?
Pat Broderick
"Elaine" Hull #245 _______________________________________________
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