Hi Bruce,
You should be able to slide the CDI unit up and take a look at the forestay.
There should be a 10" turnbuckle inside the drum, if the installation was
done correctly. Your side shrouds could be too tight.
Mast rake and mast bend are two different things. If you tilt a straight
mast aft, you've got rake.
If you compress the mast column with the backstay, it will bow forward in
the middle; that's mast bend. Forward bend means that the middle of the mast
is further forward than the bottom and top. Forward bend helps stabilize
the mast column and keep it from pumping fore and aft, espeicially when
sailing downwind in following seas. It is not ok to have an inversion in
the mast, defined as a convexity towards the stern, in general (though
advanced sailors may shape the mast that way in special circumstances)
You proablly want anywhere from 0-3 degrees of rake in the mast.
You may or may not want to tune some forward bend into the mast, depending
on your' level of expertise. It's okay to have a little "forward bend" in
the mast (defined as a convexity towards the bow), though 2" is probably too
much for your rig. I'd recommend no bend (or no more than 1/2") if you're
not familiar with how and when to use mast bend.
First of all, start with a basic tune. Loosen all the stays until they are
visibly slack. Get the mast approximately straight up and down or 1-3
degrees of aft rake (compared to the cockpit seats) in the fore and aft
directions with very light tension on the forestay and backstay, but not
floppy loose. Use enough tension to get the visible slack out the the
forestay and then tighten just a turn or two more.
Then use the mainhalyard to get the stick straight from side to side as you
tension the upper shrouds until they make a low pitched musical ote when you
strike them sharply. Pull the hoisting endt of the main halyard tight to
the chain plates on either side and use it as a "measuring tape". Then go
one turn or two tighter (that should get you to somewhere around 12%
tension). Then tighten the lower shrouds just enough so you can just hear a
musical tone when you strike the shroud sharply with a wrench. If it's just
barely tight enough to make a low-pitched note, that lower shroud is set to
about 10% tension.
Put your cheek up against the mast, pull the mainhalyard tight along the aft
face of the mast and make sure it's in a straight line side to side from top
to bottom. If it's not straight, pull on the shrouds with your hand to see
what will make it straight. Tighten that shroud or loosen the one on the
opposite side. Loosening a turnbuckle 180 degrees can make a big change at
this stage.
Then go back and check that the mast is still in the middle athwartships by
using the main halyard stretched to the chain plates. Fiddle with
everything til you get it in the middle (from side to side) and in a
straight column.
Now tighten the forestay until it's almost as tight as the upper shrouds.
Tighten the backstay until it's about as tight as the lower shrouds. If you
change the rake of the mast, it will affect the tension of the side shrouds,
so you'll have to go back and check the tension on the side shrouds. A half
turn of the turnbuckle at this stage has a lot of effect at the masthead, so
work incrementally and carefully.
That's your basic dockside tune. Next you fine tune on the water.
Now go out and sail the boat in enough wind to heel 10 degrees when close
reaching and pointing. The tiller should want to go towards the upwind
side, and you'll have to pull it lightly to windward to keep her on course.
If you've got the mast raked the right amount, you should be able to stay on
a straight course by holding the tiller towards windward about 2-4 degrees
(from centerline). That's what we mean when we say a properly tuned helm
has about 3 degrees of weatherhelm. To increase weatherhelm (or eliminate
lee helm), rake the mast aft more by loosening the headstay and tightening
the forestay. To reduce weatherhelm, do the opposite. (do this back on the
dock, not under sail unless you have a really competent person helping you).
(Weight distribution also affects weather helm, so make sure she's sitting
properly on her lines before you change the rake of the mast to affect the
helm)
While you're sailing, the leeward side shrouds should not be visibly slack.
If they are, go back to the dock and tension them a turn more at a time.
Remember, when you change the tension on any of the shrouds or stays, all
the others are affected. Keep going back and forth to keep the mast
straight (in column), centered from side to side, and with the correct
amount of rake.
That completes the basic tune for the P19.
If you've tuned the rig like this, you'll have to loosen the backstay to get
the forestay connected if you don't have a mast raising system with a lot of
mechanical advantage. Loosen the backstay perhaps 8-12 turns to
detach/attach the forestay, (and don't forget to tighten it the *same number
of turns* before you go out sailing!!!) Or install some other hardware,
like the Johnson lever release shoud adjustors.
~~~~~~~~~~~~~~~~~~~~~~~~
Advanced tuning tips:
KIDS - Dont try this at home. You need the right knowlege and hardware to do
it or else you may damage your masthead fittings. Don't try this on a stock
rig unless you really understand tuning and know what you're doing.
This is advanced sail trim technique. If you don't already understand what
I'm about to say about mast bend vs mast rake, and you're curious about it,
get yourself a good book on advanced sail trim and racing. For some reason,
the books are almost always written from a racing perspective. But the same
trimming techniques that racers use for winning races are used by expert
cruising skippers to control the sail-power for a fast, safe comfy ride in
challenging conditions. For those of you who aren't interested in fancy
tuning and all that botheration, there are other traditional techniques that
you can use in heavy wind and rough conditions, (like a fisherman's reef)
that don't require any special tuning or gear.
For those of you who know how and when to use mast bend (and understand bend
vs. rake), you can get the tune for more mast bend by doing the following:
loosen the lower shrouds to permit the middle of the mast to flex forward,
tighten the forestay a little, and tighten the backstay to compress the mast
column. An adjustable backstay compresses the column more than it pulls the
masthead backward. The lowers will tighten as you compress the mast and the
middle bends forward. Set the tension on the lower shrouds to stop the
forward bend at the desired amount, effectively using them as checkstays.
At "neutral", there's about 1" of pre-bend in my mast for increased
stability in rough sea conditions. When I tighten the adjustabIe backstay
to flatten the mainsail draft for high winds or pointing), I get almost 2"
of additional mast bend in my rig, before the checkstays (lower shrouds),
limit it. If I tighten the backstay more, only the top section of mast above
the forestay bends, loosening the leech of the main and twisting off the
top. My masthead crane is much beefier than the standard fittings.
~~~~~~~~~~~~~~~~~~~~~~
Fair winds,
Judy B
1985 WWP19 #266 "Redwing"
SF Bay, CA
-----Original Message-----
From: Bruce ParkJr [mailto:bjrpark@yahoo.com]
Sent: Monday, May 01, 2000 7:26 AM
To: WWPotter@egroups.com
Subject: [WWP] P-19 Forestay Adjustment
Hi Everybody,
I finally managed to get enough yard work done, that I
did my first practice rig yesterday.
I'm hoping that some of you can help me with the
following:
Upon fastening the forestay (with CDI roller furler)I
had to pull pretty hard to fasten it. When I did a
visual from the mast step, I saw that I actually had
(gulp..I hate to admit this) nearly a 2-1/2" forward
bend. No wonder I couldn't point worth a dang at the
end of the season last year. How do I adjust the
length of the forestay with the CDI roller furler
attached? Is there a certain look to the mast that I
should be looking for? I don't have any tension gauges
or anything like that and do the whole shebang by
visual and feel.
Also, concerning the baby stays: how tight should they
be when the mast is stepped?
That's it for now. Thank you to everybody in advance
for your help!
Bruce
P-19 #969
South Central Michigan
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