2008 RCB Slides Approval

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.


"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
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
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.


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