RCB Stay Slide Approval
From the Executive Secretary
The trial of RCB stay slides is being wound down - please read the
two statements below from Frank Bethwaite. As the Designer, Frank
is ready to specify RCB stay slides as part of the Tasar "as
supplied by the builder."
I will now be asking the World Council to approve this change.
When that approval has been given, (together with the approval of
ISAF, which Frank is requesting), Tasars fitted with RCB stay
slides, as specified below, will be "as supplied by the builder and
approved by the World Tasar Class Association" as required by class
rule A.1.2, and can be sailed in all Tasar class events.
I would like to thank Frank for the tests he carried out, and
those who invested their time, energy and money in trialling these
new slides, and found creative ways to solve the issues that came
up during the trial. These slides (which are optional, and can be
retrofitted to existing boatsl) are one more step toward keeping
the Tasar current and comtemporary.
Richard Spencer
Executive Secretary
28th March, 2008
From Frank Bethwaite
Re RCB Stay Slides
Condensed Summary of critical correspondence.
I sense that everybody is now ready to finalise this issue.
My understanding is that the refinement process has progressed
through
the following stages -
1. Mechanical stops. Functional, but deemed gross and
expensive.
2. Julian's suggestion of discarding the stop in favour of
cleating the pull-back rope in a vertical Vee cleat attached to the
shroud adjuster. Principle sound but necessity for strong vertical
pull made operation difficult.
3. Cleat shackled horizontally and flexibly to RCB slider.
Horizontal pull of half the tension a great improvement, but free
cleat difficult to "find".
4. Standing part of Pull-back line fed through bolt-hole at aft
end of cleat. This captures and stabilizes the cleat position and
makes the cleating operation simpler and more reliable.
5. A few days ago Chris Parkinson emailed me to advise that he had
tried feeding the active limb of the pull-back line from the bottom
toward the top of the cleat through a special or enlarged hole at
the front of the cleat. This positions the line at the teeth and so
should make "finding" the teeth simple and reliable. At the time of
writing this modification had not been trialed on the water.
At this point I contributed the idea that line laid in a spiral
"locks" into the Vee cleat serrations more securely than plaited or
braided line, and had he tried laid line. He hadn't, so I posted
him 2m of 4mm laid line to look at and trial if he thought
fit.
That brings my understanding of the RCB development up to date. In
my opinion the whole trialing exercise has been handled very well
indeed.
Along the way Richard's philosophical comments about doing by the
book those things the class deems proper to do by the book (e.g.
mylar sails and stay slides) but with respect to the value of
"wafting through" those occasional common sense things which do not
justify "book" treatment (e.g boom material) has been a breath of
fresh air and common sense.
Paul Ridgway has contributed further to this subject in the March
ATC newsletter.
May I suggest that either as a part of the TANSW AGM, or at a
separate "Measurers and those interested" meeting we pool
experience and opinion re RCB stay slides to date with a view to
agreeing that either the following words or words amended and
mutually agreed be deemed appropriate -
"The designer advises the Tasar Class and the Chief Measurer that
as
from 31st March 2008 licenced Tasar builders may supply new
Tasars
equipped with either -
"The original C-section track routinely supplied since 1975 -
together with an under-gunwale rigid load-bearing backing plate of
Inverted C-Section track or equivalent.
"Or
"An RCB system comprising the following fittings or their
equivalents -
2 x RC11902 Cars
4 x RC11980 Track Ends
1 x RC1190-1.0 track
2 x CL 268 Cleats
4 x RF 1850S Shackles
4mm line either laid (preferable) or braided.
An under-gunwale rigid load-bearing backing plate of solid 18mm
alloy or stainless
bar which extends approximately 75mm past each end of the track,
or equivalent
"Existing Tasars may be retro-fitted with the 19mm RCB
system.
"Note: 14mm RCB track is not class-legal.
"The distance from the bow U bolt to the bearing point of the car
shackle in the forward position shall be 2160mm and 2300mm in the
aft position. This gives positions of 285mm and 425mm respectively
behind the center of the mast pin.
"Tolerances of distances +/- 10mm.
"Tolerance of excursion 145 +/- 5mm"
Frank Bethwaite
Designer
21st March 2008
A Final Note from the Designer
We held our "interested persons" meeting at the TANSW
championships as scheduled. The key people were Trevor Hilleard,
Pres TANSW, Graham Hanna (chief measurer and trialer) and Chris
Parkinson (Immediate Past Pres W C and trialer) and me,
All are from NSW.
Four new points of interest -
• The previous day's racing had been in stronger winds. The
comment was that female crews were able to control stay tensions
fluently with the RCB equipment in conditions in which this would
not have been possible with the C-section track and sliders.
• The tension on the restraint lines is substantial. Trialers
report that plastic cleats and "soft" aluminium cleats wear
quickly. The harder anodized cleats seem to stand up.
• Laid line does indeed lock into Vee cleats securely, but at a
price.
• Because of the tension there is need to smooth very carefully
the holes in the cleats through which the rope slides. Chris
reported that his laid rope quickly chafed and frayed and the
frayed ends then tangled in the machinery and locked the
system.
The third trailer, Martin Sly (who lives in Victoria and was not
present at these NSW championships (several Victorians are) has now
advised that he is satisfied that the trial has been successful,
and can be concluded.
Frank Bethwaite
Designer
26th March 2008
RCB Stay Slides Approved
From the Executive Secretary
The class has now approved RCB stay slides, and ISAF approval is
expected shortly. On May 4th, Frank Bethwaite sent the following
email to Simon Forbes at ISAF:
Request for approval of RCB stay slides for Tasar class
Dinghy.
Dear Simon,
I request approval to substitute 19mm RCB track and slides in
place of the original C-section track and brass slides for the
shroud slide system of the Tasar Class dinghy.
The primary driver for this change is the advice by Ronstan, the
Australian makers of the C-section track, that due to the
development and widespread acceptance of the RCB system, demand for
the C-section track is withering and its production is likely to be
discontinued.
In concert with the class, I have taken a proactive view. From an
engineering point of view, the 19mm RCB system satisfies all
operating conditions.
We have appointed four crews, the immediate past president of the
World Council, the class' Chief Measurer, our Victorian agent, and
our UK licensee (Mandy Stock, Lymington) to trial the 19mm RCB
system in Australia and in the UK over the past six months. (Due to
the season, the UK exposure was short, but positive.)
The tracks and sliders have all performed without fault.
We have developed a mechanically and ergonomically efficient
restraint system which copes with the RCB system's relatively
frictionless operation.
I request ISAF approval.
Regards,
Frank Bethwaite
Designer, Tasar class dinghy.
Simon Forbes asked me to confirm that the Tasar class is happy
with the change. As five of the nine members of the World Council
have told me they approve this change, I have now told Simon the
class has approved it.
I would like to express my thanks all those who worked on
developing, testing, and improving the RCB stay slides. The new
slides will make the boat easier to sail for some crews, and are
one more step in updating the Tasar and helping to keep it popular
and relevant, while maintaining its appeal as a light, fast,
dinghy. The original tracks and slides, which are cheap, simple and
thoroughly tested, remain a fully class legal alternative to the
new slides.
Richard Spencer
Tasar Class Executive Secretary