Conference unifix::sailing

    Happen they do!  And this was one season where one lived or died by
    them.  We mainly died.  
    
    However, we did learn over the season some things.  Stuart Walker has
    had a series of articles in Sailing World over the past three or four
    months which are well worth reading.  They discuss in detail the
    various kinds of shifts and good tactics to play them.  The most
    important thing we learned is not to be greedy on the first leg.
    
    As you said, when there are two weather legs you learn on the first leg
    and max out on the second.  For this reason Stuart maintains it is best
    to play the middle on the first leg, allowing you to take advantage of
    any lift or header without locking yourself out on the layline. 
    Another reason is that you prevent yourself from looking for that big
    shift you just know is out there (but usually isn't) and putting
    yourself out of the race at the first mark.  It is a conservative
    strategy that may not win you any particular race, but will work to
    your advantage over the long run.
    
    As to our wind reading methods there are several.  While we do have
    electronics we don't rely upon them exclusively.  We shoot the breeze
    several times in the half hour before the race to try to establish any
    patterns like oscillations or clocking.  We then have a discussion
    among myself, our navigator and pitman, who is a pilot and called the
    airport that morning, where we think the wind is likely to go.  We base
    our rough strategy and starting position from there. During the race we
    always watch the compass like a hawk.  We have jumbo repeaters on the
    mast so the whole crew can participate, but you really need only one
    person to concentrate on that.  We try to play lifts and headers the
    whole leg.
    
    Another thing we learned is just how important playing the shifts
    downwind is.  Jibing is not something to be avoided.  People are much
    more reluctant to jibe than to tack when just as big of gains can be
    made there if not bigger.
    
    More later
    
    Dave

    Dave,
    
    Do you still have those articles from Stuart Walker? I you could find
    the time to copy them I would greatly appreciate it.
    
    I recently read an article about the relationship between puffs and
    major shifts. The theory is that wind velocity is zero at the surface of the
    water and increases with height - everyone know that. But the higher
    velocity air traveling above the lower velocity air is not always
    stable. The turbulance that results is called tumbling, high velocity
    veins of air dive down to the waters surface where we see them as
    puffs. 
    
       Since a shift in wind direction is supposed to come on the
    high velocity air and work down to the water, the direction of puffs 
    is supposed to predict the next major shift. Header puffs mean a header
    shift is comming etc. If the wind is going to clock to the right, there
    should be more puffs comming from the right than from the eye of the wind or
    the left for a long period of time.
    
       I haven't used this theory enough to become a firm believer, but it 
    makes sense.
    
    -Paul   

    In addition to his monthly column, Stuart Walker has a number of
    books out.  They're very thorough and not easy reading.  Neither
    are his columns.  The two that come to mind are "Advanced Racing
    Tactics" and "A Manual of Sail Trim".  I don't know how he finds
    the time.  He's a medical doctor in real life, formerly chief of
    pediatrics at Johns Hopkins Univ. Hospital.  During the last Newport
    America's Cup races he did the commentary for ESPN.  A TV critic
    in a local paper was astonished that for the duration of the races
    he never had to repeat himself on the air while maintaining a non
    stop description of the action.  When you consider that some of
    those light air races went to the max time limit, that is amazing.
    
    I just found a tattered xerox copy of an old Stuart Walker article
    that encapsulates much of his thinking on tactics.  The portion
    dealing with wind shifts appears below.
    
    PREPARATION:
    Prior to the start, determine the following:
    wind strength
    current - velocity and direction
    wind direction
    reach and run directions
    closehauled headings
    downwind jibing angles
    
    Plans for the start and the first beat should be established.
    The sailsm and the sail trim appropriate to the conditions and
    appropriate to each leg should be reviewed and arranged.
    
    GENERAL STRATEGIC PRINCIPLES
    If the wind is light, you need to decided which way to go and to
    keep going.  Get away from the fleet to one side or the other and
    avoid frequent tacks.
    
    If the wind is moderate, you need speed.  Check your sail trim,
    set your rig and sails appropriately, and then test them against
    another boat.
    
    If the wind is heavy, you need seamanship.  Keep the boat going
    and be conservative (let others make the mistakes).
    
    UPWIND STRATEGIC PRINCIPLES
    All beats can be divided into one of three categories:
    I  Oscillating winds.
    II  One side obviously advantaged.
    III  None of the above.
    
    Category I - Check the compass headings in advance for as long a
    period as possible to determine the median haedings for each tack.
    If the wind is oscillating significantly, keepto the tack lifted
    relative to the median wind, and tack when headed.
    
    Category II - If one side is obviously advantaged, assume the tack
    towards that side of the course until the maximum advantage has
    been obtained, or farther towards that advantage than any other
    competitor, but avoid the layline.
    
    Category III - When the conditions are not I or II, ignore atrategy
    and concentrate  on tactics.  Be conservative.
    
    Some other general principles:
    
    Start on the lifted tack and continue not more than two thirds of
    the way to the layline until a heading shift appears.
    
    Dig back in towards the rhumbline as soon and as often as you can.
    
    Keep inside and to wendward on subsequent tacks away from the
    rhumbline.  Keep inside and to leeward on subsequent tacks back
    to the rhumbline.
    
    Cross 'em when you can.  Don't let 'em cross you.
    
    Don't tack until boats to leeward on the same tack do.
    
    Avoid the laylines.
    
    

    
>   Keep inside and to wendward on subsequent tacks away from the
>   rhumbline.  Keep inside and to leeward on subsequent tacks back
>   to the rhumbline.
    
This looks like another way of saying - stay between your opponent
and the mark at the end of the leg and make him go to the layline 
first.

>   Don't tack until boats to leeward on the same tack do.
    
When would you apply this? It makes sense to me if you're covering a 
pack of boats but not if you're sailing your own race on the first leg.      
    
-Paul

    re .4
    
    I believe these admonitions refer to category III conditions in
    which all strategic considerations are ignored and effort is expended
    100% on tactics.  In other words, if it's not oscillating shifts
    or persistent shifts, just cover the other boats.  Under these
    circumstances you don't sail your own race.  Actions are governed
    entirely by what others do.
    
    I've been reading Walker for years.  I even met him in real life
    at a regatta.  Talks just like he writes.  The words tumble out
    and my eyes glaze over as I mumble "yes, of course, very interesting".
    The only thing I can honestly remember on the water is "don't let
    'em cross you".  I tend to obey this dictum on the theory that the
    collective wisdom of the fleet in finding a header is more accurate
    than my own.  If they're right and I'm to leeward, I gain.  If I'm
    to windward, I lose.  And if I'm on the opposite tack and get the
    lift, I get clobbered.  Of course, many heads can and often are
    just as stupid as one.
    
    On the header puff theory - this makes sense.  In fact, a header
    puff often generates an auto tack as everyone scrambles off the
    rail to get boat back upright.  For a puff to be a header there
    really has to be a dramatic change in the direction of the true
    wind.  A puff by itself will generate a velocity lift of 5 degrees
    very easily.  So a puff with no change in apparent direction is
    really a knock of 5 degrees.
    
    - gene

    Gene's comments remind me of another ploy.  They so called velocitiy
    lift or header.  When you sail through a lull and your boat speed is
    greater than it would be normally at that wind speed your tell tails
    tell you you are in a header when the wind may not have shifted
    direction at all.  The proper thing to do is to sail on without falling
    off until you bleed off your boat speed and come to the proper speed
    associated with the wind speed and the tell tails come back to normal.
    This is VERY hard to to as every instinct tells you to fall off.  Just
    the opposite when you get a puff.  It is very wierd to get a lull, heel
    to windward and have the helmsman just sit there happy as a clam.
    
    Dave

    My crew doesn't just sit there, they scream that I'm blind and blowing
    the race! I'm going to have everyone read a good article on target
    boatspeed before next year.
    
    Charlie  and Mano, are you reading this?
    
    -Paul

    Good observation, Dave.
    
    The velocity header is insidious.  If you bear off in an attempt
    to get the telltales to fly, you'll keep going lower and lower but
    the telltales still won't respond.  Because the boat is creating
    its own wind, the apparent wind will just follow you around.  Pretty
    soon you'll be sailing at 90 deg to the other boats (if not backwards).
    And if you tack, you'll swing through 180 or more degrees.  When
    I see that compass card turning like a roulette wheel, I know I've
    been suckered.
    
    - gene

>        <<< Note 1360.7 by MFGMEM::KEENAN "PAUL KEENAN DTN 297-7332" >>>

>    My crew doesn't just sit there, they scream that I'm blind and blowing
>    the race! I'm going to have everyone read a good article on target
>    boatspeed before next year.
    
>    Charlie  and Mano, are you reading this?
    
>    -Paul


Yea I'm reading this! Most of it is over my head. I'll stick with being
ignorant and continue yelling obsenities at the skipper :-). Remember,
we have that port tack start to hold over you! (oooh, stab , stab :-) )


Mano

    The best investment I can recommend is the course given over the winter
    by Ockam Instruments.  They don't plug their product too much and the
    concept of target boatspeed and its impact on tactics is well spelled
    out.  Worth the money even for the crew.  May save you some abuse ;^).
    
    Dave

    Re .5
    
    Gene,
    
    When you said if you're on the opposite tack and get the lift, you get
    clobbered, did you mean header instead of lift? I'm assuming you're talking
    about taking a knock as you duck under a group of boats. 
    
    One recommended way to sort out the direction of puffs is to have
    a crew member with eagle eyes watch the shifts moving across the water and
    compare them with the true wind direction. This way the wind velocity
    doesn't effect your estimate of the direction. 
    
    -Paul

    re .11
    
    No.  I mean lift.  If the fleet goes left and gets knocked and I
    go right, I get lifted.  When the fleet and I cross tacks again
    the fleet will be ahead.  The theory about not letting the fleet
    cross you is to minimize potential loss.  If the fleet is going
    towards a knock, the leewardmost boats will gain on the rest of
    the boats in the fleet.  If you duck the fleet, you'll be on the
    wrong side of the shift and loose.
    
    Good idea about the lookout.  But I have a hard time telling where
    the true wind really is.
    
    - gene

    Re: .12  What Gene is implying is that when the guys that go left get
    knocked, they will tack onto port and be lifted on their trip back
    toward the rumbline, while if Gen goes right he has to come back
    sometim and that will be on a header on starboard.  There were many
    weekends where we went out too far and started to see our compass tell
    us we were being lifted when we would have given our right, er, arm for
    a header.  If you really want or have to get back to the center you
    have to take a lot of sterns.  Hurts a lot!
    
    It is amazing how much a bad call can set you back.  You simply have to
    sail such a greater distance.  that's why we like courses with multipl
    windward legs so there is a chance to come back if you blow the first
    leg.
    
    Simplest rule is: Windward boat makes out on a lift, leeward boat makes
    out on a header.
    
    Dave

    Or, as somebody put it to me this season, a wind shift causes your
    course through the water to look like an arc, think of it as a wheel. 
    You want to be on the inside of the wheel relative to your competition. 
    This visualization makes a lot of sense to me.  Obviously the boat on
    the inside travels less distance through the arc than the boat on the
    outside, regardless whether the shift is a lift or a header.
    
    ... Bob
    

    
    Gene,
    
    I picked up Walker's "Advanced Racing Tactics", it's very good.
    
    His ODSSSIC factors are very interesting, but he doesn't go into
    alot of detail in this book. Do you know if his "Wind & Strategy"
    book covers the ODSSSIC stuff better?
    
    -Paul

    
    Duuuhhh.
    
    I don't remember anything about ODSSSIC.  Don't have the other book.
    
    What is ODSSSIC?
    
    - gene

    ODSSSIC is Walker's acronym for natural factors that affect 
    the outcome of a race. He has it written on his traveler thwart
    and uses a grease pencil to check off the factors in play.  
    
    O        Oscillating wind
    D        Dying or increasing wind 
    S        Sea breeze 
    S        Squall 
    S        Shoreline 
    I        Inversion breakthrough
    C        Current (tidal)
    
    For "O" conditions, follow the compass and tack on the headers.
    
    For "DSSSI" conditions, the result is usually a persistent shift.
    
    I'd like to read more about how Walker determines which factor(s) are
    in effect.
    
    -Paul 

    I ordered Stuart Walker's "Wind & Strategy" book several months ago -
    after this long wait, the bookstore tells me it's out of print.
    
    So I managed to get it from a library. It's an amazing piece of work,
    very technical and reads like a text book. He starts out with global
    theories of weather and works his toward how these factors influence
    local wind shifts on the race course (did you know that an increasing
    wind usually veers because of the Coriolis acceleration induced by the 
    earths rotation). He goes into the nature of Highs, Lows, Inversions,
    Sea breeze, Land breeze, etc and how they combine to form the wind we
    race in. There is also an excellent section on geographic wind
    shifts that you find fixed off shorelines and points.  
    
    The book finishes with an analysis of many race sites including
    Marblehead. This is a difficult book to read, but for those who are 
    serious racers - it's a must.
    
    -Paul
     

    
    
    How far offshore do shoreline effects operate?  All the books show
    that the wind is usually perpendicular to the shoreline, but how
    do you estimate wind direction as a function of prevailing wind
    direction/strength, and orientation/distance from shore?  Does Walker
    discuss this at all?
    
    
       /Jim
    

Jim,

I just started reading the book last week and it contains a mountain of 
information. I haven't made sense of it all yet, but I can give you some of the
basics.

A shoreline will affect you in many different ways. How far out it will 
affect you depends what kind of shift you're talking about. A "perpendicular
to the shoreline" shift is called refraction. As the wind blows off a 
shoreline and accelerates over open water it bends to be perpendiclar to the 
shore. The distance out depends on the irregularity of the shore, tall trees 
extend the effect. Refraction usually has a range of 1/4 mile. Walker puts this
shift in its own category, but to me it's a geographic shift. It's generated by 
local terrain and stays put. It doesn't sweep across a fleet like an 
oscillating shift, you have to sail into it. There are many geographic shifts, 
to name a few there's also the fan effect, channeling (parallel to the shore), 
barrier, and island effects. These shifts all occur close to land.

When you are farther out from shore, it still affects you. Only deep ocean
racers become free of shoreline effects. The winds we sail in are rarely 
generated by one source. If they were, this topic would be simple and sailboat
racing far more predictable. The winds we see are mostly a combination of the 
weather system wind (generated by High and Low pressure systems moving around 
the globe) and a sea breeze, or land breeze, or lake breeze, etc. (there are
many others). If two sources are operating at once from directions 45 degrees 
apart, like a weather system and a sea breeze, the resultant wind will be the 
sum of both coming from a single direction. This direction will be a function of
the relative strength of the two winds. 

For example, the wind direction will shift from the weather system direction 
to the sea breeze direction as the sea breeze grows in the late morning (the 
land has heated up) and shift back as the sea breeze dies in the afternoon. If 
the center of the weather system is moving quickly and changes our angle to 90 
degrees, this will cause a shift at mid-day back towards the weather system 
while the sea breeze is stable. Most of this stuff can be predicted by looking
at weather charts, land temp, water temp, and local knowledge.

Also, since the sea breeze begins first and lasts longest near the shore, it's
possible for half the fleet to be sailing in the sea breeze near shore and the 
other half to be in the weather system wind farther out.  

If you're interested in this, Walker's book will answer all your 
questions, if you don't fall to sleep first!

Paul