From: jamesm@lunch.austin.ibm.com (James Miller)
Newsgroups: rec.boats
Subject: 5 sailing questions
Date: 13 Oct 92 21:40:44 GMT
Reply-To: jamesm@voyager.austin.ibm.com
Organization: IBM AWD; Austin, Texas


Hello, all,

I've six questions related to sailing ranging from gritty technicalities to
general curiousity and decided to economize by putting them all in one post.
Any serious responses, either by email to jamesm@voyager.austin.ibm.com or as
follow-ups on rec.boats, would be appreciated.  (Humorous responses -- if
they're good -- might be appreciated, too.)  I'll try and get the nitty
questions out of the way first and save the gee-whiz ones for the end.

sailing question 1

The fiberglass rudder is integral with the aluminum tube rudder shaft (1 5/16"
O.D., 1 1/16" I.D.).  This shaft runs from beneath the transom up through a
tube in the hull and projects several inches above the aft deck.  Two 1/4"
holes are drilled laterally through this shaft near its top end to accept a
stainless steel bolt which fixes the tiller to the shaft.  (They can be
thought of as a single lateral hole if one thinks of the rudder shaft as solid
rather than hollow.)  Since the tiller *swivels* on this stainless steel bolt,
the bolt can sometimes swivel within the holes through the aluminum.  The
result is that the stainless threads have over time wallowed out the holes in
the aluminum so that there is considerable play (i.e. "slop" or "dead zone")
between the tiller and rudder shaft.  Under sail the effect is like driving a
car with a very worn steering pinion gear.  I'm thinking of drilling out the
holes in the aluminum shaft to accept a brass tube (with 1/4" I.D., to accept
the stainless bolt, and say 3/8" O.D.) of 1 5/16" length.  Then the aluminum
need only contend with *smooth* brass and the easily replaceable brass can
fight with the stainless bolt threads.  Does this sound OK?

sailing question 2

The main sheet is really a combination of 'center-mounted' and 'end-mounted.'
It runs from the end of the boom, down to a turning block abaft the tiller,
back up to a block on the end of the boom, along the boom to a second block at
boom's center, and finally down to a swivelling block/cam cleat combination at
the center of the cockpit.  I do not want to put a traveller across the middle
of the cockpit, but one across the aft deck just forward of the transom
wouldn't be so bad.  How much beneficial control of the main would be gained by
replacing the block abaft the tiller with a travelling block while retaining
the cockpit-centered block/cam cleat?

sailing question 3

Being pretty new at this, I'm quite confused about how to tune a rig.  "In
light wind and smooth water, adjust the sails for maximum flatness and a tight
slot to reduce turbulence and therefore drag.  In light wind and chop, adjust
the sails for greater fullness for increased drive..."  The only literature I
have on this so far is skimpy and a bit inconsistent, and I don't think I'll
have the opportunity to apprentice to a racer (=8^) any time soon.  What's a
good book to peruse to learn the basics of tuning a marconi rig?

sailing question 4

There was some discussion here recently of preparing the hull surface to
reduce its drag through the water and the 'legality' of such.  We heard about
dripping detergent off the bow (yikes!), waxing or soaping the bottom,
roughing up the middle third of the bottom, and finally of some kind of
(longitudinally?) ribbed surface from 3M on the bottom of one of Dennis
Conner's (sp?) 12 m Cup boats.  I read in a coffee table book on modern
submarines that the Soviets stumbled upon a similar phenomenon.  When they
sheathed a sub's hull in some kind of flexible, fabric-like material to
minimize the hull's sonar 'fingerprint,' they found that the resulting
rippling of the outside of this hull at speed reduced drag so much that it
went much faster than anticipated.  (Imagine -- a squishy sailboat!)  Is there
a good place (e.g., a particular issue of _Sailing_) to get a description of
the prepared surface of that 12 m America's Cup boat?

sailing question 5

Another fairly recent fad in hull designs from our Cup racing guys is the
winged keel.  (Weren't some people here talking about having their cruisers
retrofitted with these?)  It seems that this might actually do some good when
sailing *off* the wind (ddw to a broad reach), but wouldn't it merely increase
drag when sailing into the wind (beam reach to close-hauled), when the boat is
heeled over?  If this is the tradeoff, how close is it?  Is there a good
writeup on it anywhere?

Okay, I'm talked out now (and need to get back to work, too!).  If there is
sufficient direct response I'll summarize to rec.boats.
--

_________________________________________________________________

  James Miller -- developing Unix software at (!) IBM -- Austin
_________________________________________________________________

  Internet:  jamesm@voyager.austin.ibm.com   (129.35.131.245)
  ibm?net:   jamesm@lunch.austin.ibm.com     (129.35.129.93)
  VNET:      JAMESM at AUSVM6
  yaknet:    512 838-1608
  UPSnet:    11400 Burnet Rd., IMAD 9541; Austin, Texas 78758
_________________________________________________________________