I've forgotten how things work here.
Hello Bill
Hello Frank
Hello Tim
Hello Mike
Glad to be here again.
OPENING PORTS
Just got notified: 'Off Topic - Replacement Windows for Berth Portals.'
Myself installed heavy bronze elliptical opening ports, the smallest Davey
ones. Couldn't futz anymore with the aluminum that I'd spent a lot of
time and $$ on.
Obscenely expensive. Have no portrait photos, but do have a couple
incidentals.
BUT HAVE FORGOT HOW TO POST ATTACHMENTS. Can't find what
used to be here as instructions, but also the language defeated me.
The photos are in my iPhone 11. So...
RUDDER TWEEKS
The rudder. Alltho not obvious, the stock/shaft is in its original position.
Which is pretty obvious. The s-glass wraps around the shaft, not
many layers, maybe four 8oz?, cabocil/chopped strand/epoxy formed
the foil bellies, and the finishing underwater paste on top of that.
Ended up with plenty of space for the expanded diameter shaft to turn
free.
But during construction the 2" thickness at the shaft was cut back to a
vee, so that the rudder swings fully without fouling the sides of the
cove in the keel. Ended up with good access into the cove for bottom
paint. Various stage photos Ebb doesn't know how to attach here.
Can just see the 2" angle in the two photos Bill has posted.
Chamfer gives the rudder a full airfoil/wing impression. However the
whole surface of the blade is still the trailing 1/2 of an 018 formula
chord.
Cove-end of keel/rudder post is close two inches wide. Rudder blade
is 2" wide, except for the chamfers, Hydrofoil ends in a sharp 1/4"
wide square trailing tip to cut the sticky liquid cavitation before it
curls back on itself. With 20 lbs alone in the 6' of 1" diameter 655
bronze stock, the rudder itself weighs in at 57lbs on the bathroom
scale. Add our weighty bronze tillerhead to that! Yet while being
towed around the Bay from San Rafael to Sausalito behind Ian's
Sanctuary, the tiller as docile and light as a littlegull's feather !!
Blade does not copy exactly Alberg's ghost outline of the so-called
'Constellation' rudder. C. is a popular name for extreme sailboats.
This one refers to a S&S 12 meter racer that won the America's Cup
in 1964 or 5. Which would be current with the Alberg palimpsest.
Some call it a barndoor rudder. Sparkman and Stevens tank tested
the design extensively. It brings control to untroubled water at the
bottom of the keel. How much rounded corners was also examined
and Alberg seems to have followed the experts. But Ebb thinks larger
round corners will also produce larger ventilations. Since then versions
of every radius have appeared on nearly all yachts with barndoor
rudders including Alberg's CapeDorys. Sharp corners too, along with
a sharp trailing edge, to defeat and control tip vortices produced by
rudder profiles and myriad angles of heel.
Felt I had to add back a wedge of area to the top of 338 rudder - my
gut, not tank-test decision - because of 'troubled waters' at the top of
the blade, especially when heeled. No disrespect, we'll just see.
Consider also that the hole for the inboard prop also creates massive
water flow dynamics that alter any hydrofoil niceties. Full foil rudder
and lithium battery powered electric OB mounted in the well.
But I do like the Alberg 'C' much better. Note that the area of both
blades in the Ariel/Commander Manual page 144 [Stress that this
drawing appears to be authentic Alberg] both blades have equal area.
Doubtful that this barndoor rudder would be built of bronze and
mahogany like the marvelous original. Pearson wasn't ready yet for
a fiberglass one, but they should have been!
Not a Swede, just an ole Squarehead.. can't figure what C.A.Alberg
might've done.. except what's brought forward with what's being
tried here.
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