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Hi Brian,
I agree with your concept about shaft/ fitting and thats my reason for
being very comfortable with it while Frank is not.
I have to take exception to your clearance. Mayby it's a typo, but 50
thousanths is WAY to loose for ANY O ring seal in mu opinion and extrusion is
expected.
I will hace about 5 -10 thousandths. I do this by boring the sleeve
slightly undersized then welding the sleeve in place. After welding ream to size
with a propersized reamer.
I wish I could get tighter, but doing the reaming freehand that's the best
result I can get.
I am also using a Block V seal which I feel is better than an oring.
The idea ame from Gary Sluis.
Best Regards,
Jim K
----- Original Message -----
Sent: Tuesday, January 06, 2009 12:53
AM
Subject: RE: [PSUBS-MAILIST] Soft ballast
venting valve
Hi Frank,
When you figure the diameter of the shaft
and the diameter of the shaft fitting, that the shaft goes into, there is only
a difference of like 50 thousandths of an inch. Even if you forgot to
put the O ring in that fitting, it's not like going to be Niagra falls coming
into your boat. You could probably put some bubble gum on it and the
leak would stop. You would be able to address a problem like
that as soon as it occured. The hydrolics would add too much
of an extra thing for me to deal with. I wonder if there is a way
to smooth out those cast fittings so they could be polished? I
will probably put a T into my ballast vent valve inbetween the valve and the
ferro body for HP air. It would be nice to have a LP air generator for
"topping off" the ballast air so as to float yourself higher on
the surface. I seem to remember the Tang would do that to try and get
maximum speed on the surface, they would run the compressors into the
ballast and the exess air coming out the bottom of the
ballast would cut down on the friction against the water. giving
them an extra knot per hour speed.
Brian
Hi Brian. That makes good sense. Save a few bucks and go with what
works. As for matching up the two materials, There's always going to be the
corrosion factor to deal with. Zinc sacrificial anodes will help but not
eliminate the problem. On the plus side, bronze and stainless won't "gall"
when screwed together. I'm using a lot of brass bolts mated to stainless
lock nuts. Although replacement of the brass will be needed sooner than
stainless bolts would, at least I know I'll be able to get them apart
without a big hassle. Some places I'll be using stainless bolts and brass
nuts, because I need the extra shear strength of the stainless, but again,
it comes apart easily after a long time in salt water.
I too am going with the bronze valves. They are
pressure rated to 600 psi, are cheap to replace, and when polished they look
really good. Very "Capt. Nemo" like. Also, the highly polished surface
corrodes much slower than the regular cast surface. I've got quite a few of
the interior valves, unions, elbows, nipples, and related bushings and
adaptors and when polished, they look really good. The HP air will be like
yours, Swagelock and stainless tube.
I haven't cut in any through-hulls yet, but those
will all be stainless nipples. Then a bronze ball valve on each one where it
enters the sub. Complete shut-off at every penetration if a problem
develops. Even the electrical through-hulls will be valved off. I want to
get all the components mounted before I start cutting in the nipples. The
largest is 2 inch, while the smallest is 3/8 inch. The main ballast will all
be 1 inch. Maybe a little slow to submerge but I don't expect that to be a
problem.
You said you're using rod linkage to operate
your valves? Wouldn't a small hydraulic cylinder work just as well?
When the weather gets a little better, I'll
cruise down on my bike for a visit and a cold beer. Frank
D.
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