DRAFT
Rules Committee Report, November 2003
Summary of Activity - During the year, the
committee has administered a follow-on
asymmetrical spinnaker (asail) experiment
involving the addition of a second set of
spreaders to the mast to enhance structural
stability. A report from the participants was
received recently, which is appended as
Enclosure (1). The committee met via telecon on
17 October, and is offering a proposal for board
and class membership approval.
Proposal - The Rules Committee proposes that
the NCESA board and membership adopt the
following:
It
is proposed that the class approve an asail
rigged boat per the appended scantling
modifications, Enclosure (2), as a sanctioned E
Scow configuration. This is subject to the
following changes from the previous asail
configuration:
1.
The asail
will be strictly one-design with a 6 in.
tolerance on the stated dimensions.
2.
A second
set of spreaders, as described, is strongly
recommended, but is optional.
3.
It is
recommended that no set period for "phase in" or
"phase out" for either configuration be adopted.
Discussion - It has been indicated that
adding the second set of spreaders just above
the upper stay-mast intersection does
significantly add to the stability of the mast
in both the longitudinal and lateral
directions. Also, this addition appears to make
a boat so rigged slightly faster upwind.
Therefore, to provide a more durable rig, the
Rules Committee strongly recommends this
addition to the configuration. However, since a
significant number of boats are sailing
successfully without these, the committee agreed
that they be indicated in the rules as
"permitted", and thus optional.
Based on criticism from numerous members during
the previous voting period, the committee
recommends that the sail be strictly
one-design. The three "tape" dimensions of
current asails from North and Quantum vary to
nearly one foot in length. Therefore, the
committee will determine a set of recommended
dimensions from the sail makers, and insert
these in the rules with a 6 in. tolerance. In
Enclosure 2, these dimensions are shown as TBD,
currently, along with draft recommendations
subject to sailmaker verification. It is
recommended that existing sails not falling
within this range be "grandfathered".
NCESA Rules Committee
Ted
Beier, Chairman
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Enclosure 1
EXPERIMENT
RESULTS
ADDITIONAL
SET OF SPREADERS ADDED TO EXISTING E SCOW
ASYMMETRICAL RIG
SUMMARY
Pursuant to
comments that an E Scow mast rigged for
asymmetric spinnakers (asails) is too vulnerable
to failure in heavy winds, Henry Colie proposed
a further asail experiment for 2007, which was
accepted by the Board of Directors in November
2006. His proposal was to add an additional set
of spreaders to add support to the jumper
stays. These additional spreaders are located
just above the mast intersection of the upper
side stays, and are swept to roughly maintain
the longitudinal alignment of the jumpers.
Besides the original boat so rigged, five boats
at Carlyle Lake have been converted for asails
and rigged in this manner. These boats, which
have backstays, have sailed for the 2007 season,
and have performed very well. Limited
structural analysis indicates that the added
spreaders do provide additional impetus to keep
the mast from inverting longitudinally, which is
the most likely failure mode for an asail rigged
mast.
BACKGROUND
As has been
demonstrated with the asail configuration, the
reason for adding the jumper stays is to insure
that the mast stays in column. This is achieved
as a result of the jumper stays adding lateral
support and allowing the mast to be put in a
"prebend" condition by tensioning the jumpers.
There has been some question whether the
original jumper configuration was adequate
because they are extended by the original
spreaders only, which are at under 50% of the
jumper intersection height. Adding an
additional set of spreaders at approximately 73%
does improve the lateral support of the tip, and
improves the resistance to loss of prebend
(inverting).
It has not
been demonstrated that this addition is
essential, however, strength margins are
increased. This has been shown as a result of
basic structural calculations.
DESCRIPTION
The
experiment consisted of a second set of
spreaders, 16" in length, added to the diamond
stays of an asymmetric E Scow. The spreader
bracket was attached to the spar at 22'4" above
deck; just above the upper shroud intersect
point. The spar was a 1989 Melges Wedge stepped
on a 1994 Johnson. The hull was built without
backstays as on the current boats. The boat was
converted to asymmetric by Melges in 2003.
The parts
were: Spreader - Vanguard part # 204242@$39.95
ea.
Spreader Bracket -
Vanguard part #20180 @$62.85
Stainless rivets -
3/16" x ?" 4@$1.50
ea.
Parts total -
$148.75
Time required
for installation - 1 hour or less.
Tools
required - Tape measure, drill, and rivet gun.
GOAL
To reinforce
mast against loads encountered while sailing
with masthead asymmetrical spinnaker.
RESULTS
The
experiment was a complete success. The mast was
much more stable with the added benefit of
noticeably improved upwind performance.
Henry
Colie
Theodor Beier
MA-4
S-27
33 Edgewood Road
5614 Rosa
Avenue
Summit, NJ
07856
St. Louis, MO 63109-3254
scowworks@yahoo.com
tbeier@sbcglobal.net
201-401-0292
314-353-3168
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Enclosure 2
ALTERATIONS
TO SCANTLINGS FOR ASYMMETRICAL SPINNAKER
I. GENERAL
RULES
5. Yachts may
carry fittings for symmetric spinnakers,
asymmetric spinnakers, or both. However, yachts
shall not use tensioned diamond stays on the
mast while racing with a symmetric spinnaker.
II.
HULL
2. Hull
Dimensions
B.
Dimensions
10. Yachts configured
for asymmetric spinnakers shall carry a sprit
bulkhead located forward from the mast line on
the starboard side such that the loads from the
sprit are reacted by the through deck fitting
and the bulkhead. The bulkhead is positioned
square to the sprit.
III.
SPARS
-
Mast
-
Mast
standing rigging
6. Spreaders
(g) One additional pair of spreaders is
permitted on yachts rigged
with diamond stays for
carrying asymmetric spinnakers.
i. Length - 16 +
1 in.
ii. Mast intersect - 22' 4" + 2, -0 in.
7. Diamond
stays
(a) Number required - 2 for asymmetric spinnaker
configuration
only
(b) Diameter - 1/8 in. 1x19 wire min.
(c) Mast intersect
i. At
tip - 29 ft, + 4 inches
ii. At
base - 2 in., + 2 inches from the base of
the extrusion
(d) An additional
set of spreaders are permitted.
F. Devices permitted for
adjusting mast while racing.
2. General -
stays and shrouds shall only be adjustable at
end attached to deck, except for diamond stays
which shall only be adjustable at end attached
at base of mast.
4. Main and
lower shroudsand diamond stays- turn buckles or
adjustable tubes
-
Asymmetrical spinnaker bow sprit
-
Number permitted - 1
-
Material - may be constructed of
aluminum alloy or carbon fiber.
-
Diameter - 2.25 inch minimum.
-
Sectional shape- round with no taper.
-
End
devices - optional, but tack line cannot
be run internally in sprit tube
-
Sprit
and devices for flying tack line shall
not exceed 4 ft beyond bow. Measurement
does not include rub rail if installed.
-
Sprit
shall not articulate. When sprit is
fully extended, forward end shall be on
centerline, + 2 inches
athwartships. When retracted, the
outboard end of the sprit and its
fittings shall be aft of the forward
edge of the hull.
-
Vertical location of forward end of
sprit - with main halyard latched, mast
rake at 33'11"(to intersection of deck
and transom on centerline) and rig snug,
wrapping tape measure around mast,
measuring to center of bowsprit tip with
bowsprit fully extended: 34' 2-3/4"
+ 4 inches
-
Bow
sprit will have a 2:1 purchase to extend
and may be retracted using shock cord.
-
YACHT
DIMENSIONS RELATING TO SAILS
-
Dimensions
H.
Symmetrical Spinnaker Sheave Wheel - 25 ft. max
I.
Asymmetrical Spinnaker Sheave Wheel - 30 ft. max
VI. SAILS
-
Spinnakers
-
Dimensions: Spinnakers measured for a
regatta shall be one LARGE PARACHUTE
and one SMALL PARACHUTE or
one ASYMMETRICAL SPINNAKER as follows.
LARGE
PARACHUTE
SMALL
PARACHUTE
ASYMMETRICAL
SPINNAKER
1.
Luff - TBD (current
recommendation 35 ft. 0 in.; +0, -6 in.)
2.
Leach - TBD (current
recommendation 26 ft. 8 in.; +0, -6 in.)
3.
Foot - TBD (current
recommendation 20 ft. 6 in.; +0, -6 in.
4.
Mid girth (distance between
the midpoints of luff and leach) - 17ft. 6in.
maximum
5.
Foot Roach - bottom edge of
sail within 2 + 2 in. of a straight line
from tack to clew
6.
Material weight - 0.7 oz.
minimum
VII. METHOD
OF SETTING, SHEETING, AND ADJUSTING SAILS
7.
Symmetrical Spinnakers
8.
Asymmetrical Spinnaker
A. Equipment
permitted for setting, sheeting, and adjusting
1.
Halyards.
(a) Number
permitted - 1
(b)Unlimited
to material, camming or cleating devices and
snap.
2.
Spinnaker sheet and tack
line- unlimited to material, snap or cleat or
jamming device. Unlimited as to number, but see
below as to number permitted in use at one time.
B. The
permissible guys for controlling the spinnaker
are:
1. 2 Clew Sheets, or spliced to be continuous
with tail to attach to clew. Only one sheet may
be actively used to control the sail
2. 1 Tack line - method of attaching, cleating
and adjusting unlimited as long as led "1:1".
C., D., and
E., same as 4E, F, and G for symmetrical
spinnakers.